CHAPTER 1: Uses and Applications of Extracts from Natural Sources Free

Current scientific evidence about physiological, nutritional, and medicinal benefits to human health provided by the use of natural products, as well as the potential harmful effects from the use of synthetic products and consequent legislative actions restricting their use, has motivated a significant increase in the consumption of natural products.¹  In this context, extracts from natural sources play an important role as natural additives or industrial inputs to food, cosmetic, textile, perfumery, and pharmaceutical industries (Figure 1.1), influencing many characteristics of the final product. Indeed, the majority of natural extracts have more than one or two functions. They have been used as natural colorants, nutraceuticals, functional foods, preserving agents, flavors and fragrances, edible oils and fats, drugs, vitamin supplements, chemical standards, and perfumes, among others. The major natural extracts are obtained from plant sources such as seeds, leaves, flowers, berries, barks, and roots, although some of them may be obtained from animal sources such as carmine dye from female insect cochineal (Dactylopius coccus), honey from bees, squalene from shark liver, etc.

The applications of natural extracts are generally associated with the functionality derived from their active components. Usually, functional foods are obtained by enrichment with functional compounds, which are ingredients able to promote or provide a beneficial effect on human health. These compounds may also be concentrated, serving as nutritional supplements, known as nutraceuticals, which are commercialized as tablets and capsules.¹  They may also be used for technological roles, as coloring agents, conservation agents, etc., and for the production of chemicals.^2,3 

Many of the bioactive properties assigned to functional foods and nutraceuticals are provided by compounds derived from the secondary metabolism of plants, also called phytochemicals. ‘Phytochemicals’ literally means chemicals produced by plants; they play an important role in plant metabolism.⁴  Phytochemicals are not established as essential nutrients, but may have a great biological significance.⁵  In most cases they are ingested by humans as part of the diet, including in fruit, vegetables, beans, and grains, in beverages such as juices, green or black tea, coffee, etc. There are several phytochemical classes, including polyphenols (flavonoids, phenolic acids, tannins, stilbenes, coumarins, and lignans), carotenoids, phytosterols, alkaloids, terpenes, and sulfur‐containing compounds (sulfides and glucosinolates).⁶  Although there is already sufficient scientific evidence pointing to the association between effects beneficial to human health and phytochemical intake, the mechanisms of action are not yet fully elucidated. Furthermore, it is believed that many of these beneficial effects are the result of additive and/or synergistic phenomena of these compounds, being attributed to the complex mixture of phytochemicals rather than to a single compound.^7–10  Products with phytochemical compounds have many other applications in food and other industries, including pharmaceutical, cosmetics, perfumes, and textile industries. For example, many products of personal care include a wide variety of natural products in their formulation including soaps, shampoos, sunscreen, hair dye, make‐up, toothpaste, deodorants, etc.^11–14 

There are many uses of extracts from natural sources which can be grouped according to their technological role: coloring agents, functional food, nutraceuticals, preserving agents, flavors, fragrances, and edible oils.

Coloring agents or color additives are any pigment, dye, or substance that produces color when it is added to a product. The coloring agents may be found in liquid, solid, semi‐solid, or gel forms. Due to the large availability of food coloring agents there are several other non‐food applications that explore their properties, including cosmetics, pharmaceuticals, and medical devices. Natural colorants are extracted by various processes and classified according to their color, chemical composition/structure, biological function in plant/body (chlorophyll, hemoglobin, etc.), and physical properties (solubility). The main dyes from plant sources are red (Brazil wood, sugar, etc.), orange (saffron flower, Crocus sativus), yellow (chamomile, Anthemis tinctoria), green (ragweed, Ambrosia artemisiifolia), and blue (indigo, Indigofera tinctoria). The main food dyes from animal sources are sepia (cuttlefish bag), red (kermes lice), and purple (murex shellfish).¹⁵ 

Besides the technological function of several well-known natural coloring agents, the phytochemicals may have other biological functions and play a role on the prevention of diseases.^16–19  Functional foods, nutraceuticals, food supplements, and antioxidants belong to an economically important sector of the global food market.^20–24  Examples of potential applications include reducing the risk of cardiovascular disease, cancer, diabetes, inflammation, and osteoporosis. Among the various functional effects, it is important to highlight the effects on gastrointestinal functions and hormonal modulation.^25–27 

Furthermore, preserving agent activity, antibacterial activity, and antifungal activity also represent an economically important sector of the global natural products market. Certain types of food preservatives are needed to ensure the quality of the final product. Most chemical preservatives widely used are weak organic acids (e.g. ascorbic acid and benzoic acid) used in synergistic combinations.²⁸  In this case, the antimicrobial and antifungal properties of essential oils are considered to be the most important.²⁹ 

Highly conjugated systems which absorb electromagnetic radiation between wavelengths of 400 nm to 800 nm appear to be colored. Color can provide a pleasant aspect to the substrate as well as express emotions and ideas.³⁰  Color is often the first notable sensorial characteristic that influences the expectations of consumers and also influences quality‐related decisions during visual inspections.^31,32  Color plays an important role in quality perception indicating our expectations, perceptions, susceptibilities to, and preferences for products, as it is used to indicate good quality, to assist marketing, and to satisfy consumers.³³  The color of food, pharmaceutical, and cosmetic products can be the result of natural pigments present in the matrix used; coloration formed upon heating, processing, or storage; or the addition of natural or synthetic colorants.³²  Colorants or color additives are the terms for all soluble or solubilized coloring agents (dyes or pigments), as well as insoluble pigments, employed to impart color to a material.³¹  The mechanism of color production is due to a molecule‐specific structure (chromophore) of chemical compounds that absorbs light in the wavelength range of the visible region known as pigments. Those chromophores capture energy and the excitation of an electron from an external orbital to a higher orbital is produced; the non‐absorbed energy is reflected and/or refracted to be captured by the eye, and neural impulses are generated, which are transmitted to the brain where they can be interpreted as a color.³⁴ 

Coloring agents can be defined by their origin as natural, synthetic, or inorganic colorants. Natural pigments are produced by living organisms. Synthetic colorants or dyes are synthetized by chemical reactions. Inorganic pigments can be found in nature or can be reproduced by synthesis.³⁴  Synthetic organic dyes have been recognized for many years as the most reliable and economical coloring agents because they are superior to natural pigments in tinctorial power, consistence of strength, range, and brilliance of shade, hue, stability, ease of application, and cost effectiveness, being the most applied source of color additives used in the food, pharmaceutical, and cosmetic industries.^32,35  However, during the last few decades, the use of synthetic dyes is gradually receding due to an increased environmental awareness and to potential harmful effects of either toxic degraded products or their non‐biodegradable nature.³⁰  Furthermore, the safety of synthetic dyes has been a matter of concern since high levels of toxicity, allergic reactions, and carcinogenic potential have been identified following their consumption as coloring agents.³⁵  In this context, there is an increased interest in further use of colorants from natural sources instead of synthetic dyes, as a consequence of perceived consumer preferences as well as legislative actions.³² 

Natural pigments (see Figure 1.2( are defined as dyes or colorants obtained from natural sources, such as plants, animals, and microorganisms. Nevertheless, the majority of commercial natural colorants currently used are extracted from plant sources such as roots, fruits, barks, leaves, wood, fungi, and lichens. Flavonoids, carotenoids, and chlorophyll are the major contributors to the natural colors of most plants, with betalines and curcumin playing a minor yet significant role.³⁶  However, there are some natural pigments derived from invertebrates, such as the cochineal pigments extracted from female coccid insects; the most well‐known is the carminic acid obtained from the female Dactylopius coccus Costa.³⁶  All natural pigments are unstable and participate in different reactions, so the produced color is strongly dependent on storage and processing conditions. Natural colorants are much more unstable than synthetic dyes with respect to physical (temperature, light), chemical (oxidizing or reducing agents, acids, alkalis), and biological (enzymes, microorganisms) factors.^32,33 

This section discusses the major natural colorants commercially used and their application in food, pharmaceutical, and cosmetic industries. The main natural pigments are categorized according to their chemical structure as: isoprenoid derivatives (carotenoids); tetrapyrrole derivatives (chlorophylls and hemes); and benzopyran derivatives (anthocyanins, betalains, and curcuminoids).

Carotenoids are the largest, most important, and most widespread group of pigments found in nature.³⁷  They are responsible for many of the brilliant red, orange, and yellow colors of fruits, vegetables, fungi, and flowers, and also of birds, insects, crustaceans, and trout.³⁴  They are usually fat soluble and associated with lipid fractions.³⁸  However, they can be synthesized only by plants and microorganisms. The chemical structure of carotenoids consist in a symmetrical polyisoprenoid structure formed by head‐to‐tail condensation of two C₂₀ units, which is modified by cyclization, addition, elimination, rearrangement, and substitution, as well as oxidation.^34,39  Due to the presence of the conjugated double bonds, carotenoids can exist in cis and trans forms, but cis isomers are less stable than the trans form due to stoichiometric conformation; therefore the majority of natural carotenoids are in the all‐trans configuration.³⁹  Based on their structure, carotenoids (Figure 1.3) are divided in two classes: (i) carotenes, which are pure polyene hydrocarbons; they contain only carbon and hydrogen atoms, including acyclic lycopene and bicyclic β‐ and α‐carotene; (ii) xanthophylls, containing oxygen in the form of hydroxy (lutein), epoxy (violaxanthin), and oxo (canthaxanthin) groups.⁴⁰ 

Carotenoids perform important functions in plants as attractants for pollinators, as accessory light‐harvesting pigments at wavelengths where chlorophyll does not absorb, and as photoprotective agents preventing photo‐oxidative stress.⁴¹  The most common natural carotenoid extracts used as color additives for foodstuffs are obtained from annatto, paprika, and saffron. Many other sources, including alfalfa, carrot, tomato, citrus peel, and palm oil, are also used.³²  Evidence of trends in looking for natural sources of carotenoids can be noticed from the patents that have been recently deposited worldwide on the subject.⁴² 

Annatto (E160b) is an yellow‐red natural carotenoid coloring agent obtained from the seed coat of the tropical shrub Bixa orellana L.⁴³  The annatto tree is native to Central and South America, but it is also grown in Africa and Asia, being especially popular in Brazil, Peru, Bolivia, Ecuador, Jamaica, the Dominican Republic, East and West Africa, India, and the Philippines.⁴⁴  The major coloring component in annatto extract is bixin (>80%). This pigment is primarily present as the cis‐bixin isomer, but other pigments derived from bixin as trans‐bixin, cis‐norbixin, and trans‐norbixin are also present, although they may have different colors.⁴⁴  Bixin is a dicarboxyl monomethyl ester carotenoid with a C₂₅ skeleton called apocarotenoid, whose biosynthesis has been suggested to take place by the oxidation of a normal C₄₀ carotenoid such as lycopene.^43,44  Annatto pigments can be separated from annatto seeds basically by two ways: (i) the method most used industrially consists of mechanical abrasion using a suitable suspending agent (e.g. vegetable oil, aqueous potassium hydroxide, or aqueous sodium hydroxide), followed by removal of the seeds (sieving); (ii) the second method consists of extraction with one or more organic solvents, which is also used as a means to produce annatto concentrates.^44,45 

The most conventional extracts of annatto available are the bixin‐rich oil extract and the water‐soluble powder norbixin‐rich extract.^43,46  While the bixin‐rich oil extract is an orange‐red pigment, the norbixin‐rich extract (a water‐soluble powder) is a yellow‐orange pigment. Annatto is used as a coloring agent in a wide range of foodstuffs such as butter, margarine, cheese, fats, cereals, baked goods, snacks, beverages, meat, and fish products.^43,47  Annatto oil extract is one of the most common colorants used for high‐fat food products. Even though conventional methods are widely used extraction techniques, they present many drawbacks such as high energy costs, low selectivity, environmental concerns, toxicity, and the generation/retrieval of large quantities of solvent waste.⁴⁴  In this context, many researchers have been studying supercritical and ultrasound‐assisted technologies as alternative extraction techniques to obtain annatto pigments.^48–52 

Paprika oleoresin (E160c) is the orange‐red, oil‐soluble extract generally obtained from dehydrated and milled fruit of certain varieties of red peppers (Capsicum annuum L.).⁵³  Paprika oleoresin recovery uses hexane as extraction solvent, followed by miscella and meal disolventization, and finally oleoresin degumming. The paprika oleoresin is used in formulating nutraceuticals, colorants, and pharmaceuticals. It can become water soluble by microencapsulation in gelatin or Arabic gum.⁵⁴  Because of its high coloring capacity, and in some cases its peculiar pungency, paprika is one of the most widely used food colorants for culinary and industrial purposes; it is applied to modify the color and flavor of soups, sausage, cheese, snacks, salad dressing, sauces, pizza, and confectionary products.⁵³  Paprika oleoresin is recognized for its self‐limiting use for technological and sensorial reasons; as with any other spice or flavor, too high levels can adversely impact the product's flavor profile balance.⁵⁵ 

The quality of paprika is evaluated through red color intensity and degree of pungency. The intense red color mainly originates from ketocarotenoids, capsanthin, and capsorubin (Figure 1.3), formed in the fruit during ripening. The yellow carotenoids of paprika, which are precursors of ketocarotenoids, mainly comprise zeaxanthin, violaxanthin, antheraxanthin, β‐cryptoxanthin, β‐carotene, and capsolutein.⁵³  The degree of pungency is originated from the group of pungent components called capsaicinoids, from which capsaicin and dihydrocapsaicin represent over 80%.⁵³ 

Saffron, an extract from flowers of Crocus sativus, has been appreciated since Mesopotamian times for its biological, aromatic, and flavoring properties, but also particularly due to its color.⁵⁶  The sensorial properties of saffron extract are given by the presence of three carotenoid derivatives (crocin for color, picrocrocin for flavor, and safranal for aroma), mainly synthesized during flowering. These metabolites are produced by oxidative cleavage of zeaxanthin, followed by oxidative modifications and glycosilations.⁵⁷ 

Crocin, the major color component of saffron, is the digentiobioside ester of apocarotenic acid (crocetin). Crocetin, like bixin, is a dicarboxylic carotenoid.³⁶  The same pigment may be obtained from the flowers of C. albifloris, C. lutens, Cedrela toona, Nyctasthes arbortristes, Verbascum phlomoides, and Gardenia jasminoides.³⁶  Other carotenoids have been found as a minor fraction of the total pigments of saffron, such as phytoene, phytofluene, tetra‐hydrolycopene, β‐carotene, ξ‐carotene, zeaxanthin, and lycopene, but their color influence in saffron filaments has not been deeply studied as they are negligible compared to crocetin esters.⁵⁶  In addition to color, certain flavoring compounds (mainly picrocrocin and safranal) impart a distinct spicy flavor in saffron extract. Different studies have demonstrated that crocins have several nutraceutical properties including antioxidant, hypolipidemic, neuroprotective, antidepressive, hypocholesterolemic, antitumor, and anticarcinogenic activities.⁵⁷ 

The saffron extract has many culinary and industrial applications, as a pigment in beverages, cakes, bakery products, curry products, soups, meat, and certain confectionery goods. However, the use of this colorant is restricted by its high price and pungency. Generally, it takes about 140 000 stigmas from saffron flowers to produce about 1 kg of powder. Combined with the high production cost, it makes saffron one of the most expensive coloring agents in the world.³⁶  The price of saffron depends on its quality, which is closely related to the area of production – in an analogous way to wine.⁵⁸  In the case of saffron, the best results for solid–liquid extraction of crocins are obtained with mixtures of ethanol:water and methanol:water.⁵⁷  The use of a green solvent, such as ethanol, rather than a toxic solvent, such as methanol, is, nevertheless, preferred.

β‐Carotene is one of the most widely used sources of pro‐vitamin A and food colorant in the world, with a global market estimated to surpass USD 280 million in 2015.⁵⁹  The pro‐vitamin A activity is the main nutritional function of β‐carotene.⁵⁹  Furthermore, β‐carotene is also used as coloring agent of fat‐based products, in food, pharmaceutical, and cosmetic industries. It is authorized as a food ingredient, with extremely strong coloring properties, imparting the desired color to foods even at ppm content. β‐Carotene can also act as antioxidant, cell communicator, UV skin protector, enhancer of the immune response, and reducer of the risk of degenerative diseases such as cancer, cardiovascular diseases, cataract, and macular degeneration.^59–62 

The majority of the β‐carotene commercially available in the world is synthetically produced from β‐ionone.⁶³  Alternatively, the production of β‐carotene can be reached on a biotechnological basis, using filamentous fungi, bacteria, microalgae, and yeasts as producers, or by extraction from vegetable sources. The β‐carotene originated from vegetables is generally obtained by solvent extraction with organic solvents, e.g. hexane, acetone, ethyl acetate, ethanol, and ethyl lactate, from carrot and palm.⁵⁹  However, alternative techniques have been studied in order to improve the selectivity and quality of the extracts – such as ultrasound‐assisted extraction, supercritical fluid extraction, and enzyme‐assisted extraction, among others.⁶⁴ 

Carrot (Daucus carota) belongs to the Umbelliferae family and is one of the most important root crops. It is cultivated for its fleshy edible roots, which are consumed by both humans and animals.⁶⁵  Carrot is mostly a fresh‐consumed food crop, and only a minor proportion of the whole production is processed for exploitation in agrofood, pharmaceutical, nutraceutical, and cosmetic industries (especially for making skin protective preparations).⁶⁶  Carrot extract is commonly obtained with organic solvents, and it is often commercialized as a natural food colorant. Generally, it is mixed with jojoba, corn, sunflower, or other plant oils before marketing.⁶⁶  β‐Carotene constitutes the largest portion (60–80%) of the carotenoids in carrot extracts, followed by α‐carotene (10–40%), lutein (1–5%), and other minor carotenoids (0.1–1%) such as lycopene and zeacarotene.⁶⁷ 

Fruits from the Arecaceae (palm) family, from the Amazon region, as buriti and palm oil, are the richest source of carotenoids among vegetable materials. Buriti is the richest source of carotenoids with 466 mg/kg raw material, from which about 75% is β‐carotene.⁶⁸  Crude palm oil is an yellow‐orange fat‐soluble extract obtained from the mesocarp of the palm oil fruit (Elaeis guineensis); it also has a high content of β‐carotene (500–700 ppm), and it is extensively cultivated, which makes it one of the richest sources of this carotenoid found in nature.⁶⁸  Commercial crude palm oil is obtained from the mechanical screw pressing of mesocarp of palm oil. The conventional milling process consists of: (1) sterilization of fresh fruit bunches for termination of enzymatic hydrolysis of oil; (2) stripping and digestion of fruits; (3) screw press for the extraction of crude oil; (4) screening of crude oil using a vibratory mechanism; (5) clarification of crude oil from water; and (6) centrifugation and vacuum drying of the oil.⁶⁹  The process to obtain carotene‐rich palm oil basically involves two stages: a pretreatment step and a short path distillation. The pretreatment of the crude palm oil includes degumming and bleaching using conventional refining methods, while the short path distillation is carried out to deodorize and deacidify the crude palm oil. The existing technology is able to retain >80% of the carotenes present in the oil. The major drawbacks of the process is the necessity of several processing stages and the use of high temperatures which may contribute to carotene degradation.^70,71 

Lycopene, a C₄₀ polyisoprenoid compound containing 13 double bonds (Figure 1.3), is the most abundant carotenoid in ripe tomatoes (Lycopersicum esculentum), representing approximately 80–90% of the total pigment content.⁷¹  Low amounts of other carotenoids such as α‐, β‐, γ‐, and ξ‐carotenes, phytoene, phytofluene, neurosporene, and lutein are also present in tomatoes. Lycopene provides the bright red color to tomato, making it commercially important as a natural pigment.

The molecular structure of lycopene consists of a long chain of conjugated carbon–carbon double bonds, which make lycopene susceptible to chemical changes if exposed to light or heat.⁷¹  Lycopene exists in cis and trans isomeric forms, but occurs in nature primarily in the trans form, which is the most thermodynamically stable.⁷¹  However, when tomatoes are processed, some of the lycopene is isomerized into cis forms.⁷¹  Lycopene cis isomers have also been detected in plasma and tissue samples at significant levels, apparently being isomerized in vivo. In addition, cis‐lycopene isomers are also found to be more bioavailable than the natural trans form.^64,71,72 

Lycopene (E160) can be commonly obtained by chemical extraction, since it is soluble in highly toxic organic solvents such as hexane, benzene, chloroform, and methylene chloride.⁷³  In the last years, besides tomato, there has been an increasing interest in recovering lycopene from the waste streams from the tomato‐processing industry. Lycopene is also industrially produced by chemical synthesis in which C₄₀‐carotenoids are efficiently produced by double Wittig olefination of the corresponding C₁₅‐phosfonium salts with C₁₀‐dialdehyde.⁷¹  Like β‐carotene, it is authorized as a food ingredient with extremely strong coloring properties.

Besides its coloring application, lycopene acts on human health by preventing prostate, bladder, pancreas, and digestive tract cancer, and by its capacity to quench singlet oxygen, which is about three times higher than β‐carotene's.^74,75 

Chlorophyll is the most widely distributed natural plant pigment in nature; it is vital to the survival of both plant and animal kingdoms due to its critical light harvesting role in photosynthesis.^32,72–77  Photosynthesis is a process that converts solar energy into chemical energy, using it together with water and carbon dioxide to produce oxygen and carbohydrates. The products from this chemical process reflect its significance, with carbohydrates being the primary building block for plants and oxygen being necessary for the survival of the animal kingdom.⁷⁸ 

Chlorophyll is a porphyrin pigment, made up of four pyrrole rings joined together via methine linkages. It is a dihydroporphirin derivative chelated with a magnesium ion within the center of the porphyrin structure, held in position by two covalent and two coordinate bonds (Figure 1.4).^32,36  The magnesium can be easily released from the molecule through acid‐catalyzed hydrolysis to give olive‐brown pheophytin.³⁶  Replacing Mg by Fe or Sn ions yields grayish‐brown compounds, while Cu or Zn ions retain the green color.³²  Chlorophylls are diesters: one carbonyl group is esterified with methanol and the other with phytol, a C₂₀ monounsaturated isoprenoid alcohol.³²  Upon removal of the phytyl group by hydrolysis in dilute alkali, or by the action of chlorophyllase, green chlorophyllin is formed. Removal of Mg and the phytyl group, which commonly occurs in conventional extraction, results in olive‐brown pheophorbide formation.³² 

Chlorophylls and pheophytins are lipophilic due to the presence of the phytol group (C₂₀), while chlorophyllins and pheophorbides without phytol are hydrophilic.³²  The chlorophyll molecule is not isolated, but comprises a family of substances similar to each other, designated chlorophyll a, b, c, and d. Chlorophyll a (blue‐green) and b (yellow‐green) are the most abundant and important of this family, occurring in plants in a ratio about 3:1, while the chlorophyll c and d are commonly found in algae.⁷⁹  Chlorophyll b differs from chlorophyll a in that the methyl group on C₃ is replaced with an aldehyde.³² 

Chlorophylls have received attention for a long time, not only because of their significance in living systems but also because of their potential relevance as natural pigments in a limited range of applications. The intense green color of natural chlorophylls suggests that they may be useful as oil‐soluble color additives in food, pharmaceutical, and cosmetic products. However, in practice natural chlorophylls are rarely used as colorants for a range of reasons:⁷⁷ 

1. the co‐extraction of carotenoids, phospholipids, and other oil‐soluble substances results in products with diversified composition and variable levels of pigments, which makes subsequent purification steps indispensable;

2. the endogenous plant enzymes and extraction conditions employed can easily promote chemical modification of the sensitive chlorophylls, yielding unattractive brownish‐green degradation products such as pheophytins and pheophorbides.

Consequently, it is more expensive and unstable than artificial coloring agents and therefore widespread application of natural chlorophylls as colorants is limited.³²  To overcome some of these drawbacks, semi‐synthetic, metal‐chelated, and water‐soluble chlorophyll derivatives, called chlorophyllins, have been produced as promising alternatives to generate colorants with a higher stability and tinctorial strength.⁷⁷  The most common stabilization process is chemical modification by replacing the magnesium center with a copper ion.³²  Copper is much more stable than magnesium in relation to the aggressive conditions of processing and storage at low pH, high temperatures, and exposure to oxygen and light. Besides, the copper complex is not absorbed by the body and is removed in its entirety as an excretion product, being considered safe to be used in most countries as a food additive.⁷⁸ 

The commercial production of chlorophyll is generally carried out by two different ways: obtaining a water‐soluble extract or an oil‐soluble extract. The first and common step for both processes is the extraction of pheophytin using aqueous solvents, such as chlorinated hydrocarbons and acetone, from dried plant materials. The pheophytin crude extract is then further processed to give a more stable copper complex.³²  Both the oil‐soluble and water‐soluble forms of chlorophyll are commercially available in the form of the stable copper complex (chlorophyllins, E141). Both forms are relatively stable towards light and heat. However, unlike the water‐soluble chlorophyll, the oil‐soluble form is not very stable in acids and alkalis.

A major portion of the commercial chlorophyll is used in the food industry for coloring dairy products, edible oils, soups, chewing gum, sugar confectionery, and pet food. Chlorophyll preparations for the food colorant market are mainly obtained from alfalfa (Medicago sativa) and nettles (Urtica dioica). Brown seaweeds, which are the commercial source of alginates, are also an interesting source of chlorophyll because as in single‐cell phytoplankton, they contain chlorophyll c, which is more stable than chlorophyll a and chlorophyll b.³² 

The pharmaceutical and cosmetic industries also use chlorophyll and its derivatives.³⁶  Chlorophyll is similar in chemical structure to hemoglobin and, as such, is predicted to stimulate tissue growth in a similar way through the facilitation of rapid carbon dioxide and oxygen interchange. Due to its growth stimulation property, chlorophyll has been used to improve the healing process in the treatment of certain gastrointestinal diseases such as ulcers, oral sepsis, and proctologic disorders.⁷⁸  Additionally, chlorophyll was found to remove odors from the wound after a few applications. Its non‐toxic nature, antibacterial property, and deodorizing function make chlorophyll a key product in the treatment of oral sepsis. Chlorophyll a and its derivatives also have potent antioxidant properties. Chlorophyll derivatives such as pheophorbide b and pheophytin b have always been known as strong antioxidants. However, these derivatives exist in very low concentrations in fruits and vegetables.⁷⁸ 

Anthocyanins (from the Greek anthos, a flower; and kyanos, dark blue) are the largest and most important group of water‐soluble and vacuolar pigments in nature. They comprise a major flavonoid group that is responsible for cyanic colors ranging from orange/red to violet/blue of most flowers, fruits, and leaves of angiosperms commonly found in nature. They are sometimes present in other plant tissues such as roots, tubers, stems, bulbils, and are also found in various gymnosperms, ferns, and some bryophytes.⁸⁰  Anthocyanins are glycosylated polyhydroxy and polymethoxy derivatives of the flavylium cation (phenyl‐2‐benzopyrylium cation), also known as aglicone or anthocyanidin (Figure 1.5), which contains conjugated double bonds responsible for absorption of light around 500 nm causing the typical color of these pigments.⁸⁰  The sugar moieties are usually attached to the anthocyanidins via the 3‐hydroxyl or 5‐hydroxyl positions and to a lesser extent the 7‐hydroxyl position. The anthocyanin sugars may be simple sugars, most commonly glucose, galactose, rhamnose, xylose, fructose, and arabinose, or complex sugars such as rutinose and sambubiose. These sugars may occur as monoglycosides, diglycosides, and triglycosides substituted directly on the aglycone. The sugar moieties may be acylated; the most common in order of occurrence are coumaric, caffeic, ferulic, p‐hydroxy benzoic, synaptic, malonic, acetic, succinic, oxalic, and malic. The first five are aromatic acids while the others are aliphatic acyl acids.^36,81 

Chemically, the major factors that influence the color of these pigments are the degree of hydroxylation/methoxylation of the anthocyanidin B ring and the nature of sugar and/or acid conjugations. An increased number of hydroxyl and/or methoxyl groups on the B ring of an anthocyanidin results in a bathochromic shift of the visible absorption maximum, which has a bluing effect on the color produced. Substitutions on the R groups of the B ring may also affect the stability of the pigments; hydroxylation of the B ring has been reported to decrease the stability of the anthocyanin while methoxylation increases stability. Sugar substitution of the anthocyanidin may increase the visible absorption maximum of the pigment, producing a more red‐orange color. Acylation of the sugar substitutions and/or individual anthocyanidins may also produce bathochromic (increased wavelength) and/or hyperchromic (increased absorption) shifts, altering the spectra of a compound.⁷⁷ 

The main drawback of the application of anthocyanins as natural colorants is their high instability and easily susceptibility to degradation during storage and processing. Anthocyanin color stability is strongly affected by pH, temperature, chemical structure, anthocyanin concentration, oxygen, light, enzymes, and other accompanying substances such as ascorbic acid, sugars, proteins, sulfites, co‐pigments, and metallic ions, among others.⁸⁰ 

Anthocyanin color stability shows great susceptibility toward pH. At any given pH level, anthocyanins exist as an equilibrium of different chemical forms. They typically exhibit an absorption maximum at a pH of 1 when the anthocyanidin is in its most stable form, known as the flavylium cation. In this form, the pigment produces a bright orange‐red to violet color, attractive for many applications. However, at a pH of 4.5 the flavylium cation suffers a hydration generating the carbinol pseudo‐base (colorless) which due to its high instability converts to its chalcone form. As the pH approaches 6 the color becomes purple. In a pH environment of 7 the flavylium cation loses the proton producing the quinonoidal base form which is characterized by its dull blue to green color.⁷⁷  The pigment turns into a deep blue when the pH is between 7 and 8. Further increase in pH sees the anthocyanin pigment turning from blue to green and then to yellow. Several studies reported a logarithmic course of anthocyanin degradation with an arithmetic increase in temperature, indicating that heating strongly accelerates anthocyanin pigment destruction; the magnitude and duration of heating have a strong influence on anthocyanin degradation.⁸² 

Many studies have demonstrated that oxygen has a detrimental effect on anthocyanin stability, amplifying the impact of other factors on degradation processes.⁸⁰  Light also accelerates anthocyanin degradation. Some investigations have proved that light has a highly significant negative effect on anthocyanin stability during storage, especially in the presence of sugar.⁸⁰  The presence of enzymes in the plant matrix is also an important intrinsic factor on anthocyanin stability. The most common anthocyanin‐degrading enzymes are glycosidases, which break the covalent bond between the glycosyl residue and the aglycone of an anthocyanin pigment, resulting in the degradation of the highly unstable anthocyanidin. Peroxidases and phenolases, such as phenol oxidases and polyphenol oxidases, which are both found naturally in fruits and berries, are also common anthocyanin‐degradating enzymes.⁸⁰  Ascorbic acid may have a protective effect towards anthocyanins because it reduces the o‐quinones formed before their polymerization.⁸⁰  Sugars, as well as their degradation products, are known to decrease anthocyanin stability; their effect depends on the anthocyanin structure, concentration, and type of sugar.⁸⁰  Sulfates and sulfites generally used as preserving agents in foodstuffs have a detrimental effect on anthocyanin stability, producing colorless sulfur derivative structures by replacement in positions 2 or 4 (Figure 1.5).

There are several mechanisms applied in the process of anthocyanin stabilization; the most common are encapsulation and co‐pigmentation. Some studies suggest that the co‐pigmentation of anthocyanins with other compounds is the main mechanism of stabilization of color in plants.⁸³  In this phenomenon the pigments and other colorless organic compounds, or metallic ions, form molecular or complex associations, generating a hyperchromic effect and a bathochromic shift in the absorption spectra of the UV visible region.⁸³  There are two types of co‐pigmentation reactions:^80–83 

1. intramolecular co‐pigmentation with the aromatic groups of hydroxycinnamic acids;

2. intermolecular co‐pigmentation with colorless substances such as flavonoids, alkaloids, amino acids, organic acids, nucleotides, polysaccharides, metals, or another anthocyanin.

The co‐pigments are systems rich in π‐electrons, which are able to associate with flavylium ions, which are rather poor in electrons. This association gives protection for the water nucleophilic attack in the 2 position of the flavylium ion and for other species such as peroxides and sulfur dioxide in the 4 position.⁸³ 

Grape extracts (Vitis vinifera) are the most widely used anthocyanin sources of natural colorants (E163). Nearly all the commercially available anthocyanins, known under the generic name of enocyanin or enocianina, are obtained from grape skin and other by‐products of the wine industry.^81,84  The generic product known as enocyanin is obtained by solvent extraction from the skins of wine grapes. Another source is lees, formed in the bottom of tanks of grape juice during fermentation. A precipitate formed by anthocyanins and proanthocyanins on the bottom of the tanks provides a rich source of pigments, which have been approved for food use by the FDA since 1981.⁸¹  Grape extracts are rich in anthocyanins complexed with other compounds, such as mono‐, di‐, or tri‐acylated and di‐ or tri‐glycosylated anthocyanins, which are much more stable under processing and storage conditions than monomeric anthocyanins due to co‐pigmentation. Anthocyanins may be easily obtained in high quantities from grapes, as they represent about a quarter of the annual fruit crop worldwide.^81,84 

Besides grapes, other fruits such as concentrated juice of blackcurrant,⁸⁵  elderberry,^86,87  cranberry,⁸⁸  raspberry,⁸⁹  and cherry^84,90,91  have been studied as potential sources of anthocyanins. Also, several vegetable extracts have been used as coloring agent sources, including red cabbage, purple sweet potato,^92,93  radish,⁹⁴  and black carrot.^95,96  These vegetable extracts have been shown to be rich in acylated anthocyanins, which improves the color stability during processing and storage.⁸⁴  Depending on the food matrix in which the anthocyanin extracts are intended to be used, other ingredients may be added in order to improve both solubility and color stability.

With a correct formulation of different ingredients, as well as adequate processing and storage conditions of the food product, a wide range of stable and attractive color hues may be obtained for several food matrixes. Commercial applications of anthocyanins as food colorants include soft drinks, fruit preserves (jams, canned fruit), sugar confectionary (jellies), dairy products (mainly yogurts), dry mixes (acid dessert mixes and drink powders) and more rarely frozen products (ice cream) and a few alcoholic drinks.⁸⁴ 

Betalains are water‐soluble vacuolar nitrogen‐containing pigments (Figure 1.6) with colors ranging from yellow‐red to violet, which are commonly found in plants of the order Caryophyllales as well as in some Basidiomycota.⁹⁷  Chemically, they are immonium conjugates of betalamic acid; they are subdivided in two structural groups, the red‐violet betacyanins (540 nm) and the yellow betaxanthins (480 nm).^34,98  Betacyanins are derivatives of betanidin, an iminium adduct of betalamic acid and cyclo‐DOPA (cyclic 3,4‐dihydroxyphenylalanin), whereas betaxanthins result from the condensation of α‐amino acids or amines with betalamic acid.^97,98  The major components found in betacyanins and betaxanthins are betanin and vulgaxanthine I and II, respectively.³⁶ 

Although structurally related to alkaloids, betalains have no toxic effects in human health as can be deduced from the fact that they are present in high amounts in foodstuffs; therefore they are considered a safe natural colorant source.³⁴  Commercial production of betalains often involves countercurrent solid–liquid extraction with aqueous methanol from plant tissues or cell cultures. A slight acidification of the extraction medium, generally by ascorbic acid addition, may be useful to promote betalain stabilization and to inhibit the possible oxidation by polyphenoloxidase (PPO).^98–101  Sometimes inactivation of degradative enzymes are achieved by a short heat treatment (70 °C, 2 min).³⁴  The extraction process is followed by aerobic fermentation, generally with Candida utilis, to remove the large amount of sugar present. Betanin (E162) is the only betalain approved for use in food and it is almost entirely obtained from red beet (Beta vulgaris subsp. vulgaris).⁹⁷ 

Although betalins are well suited for coloring low‐acid food due to their stability at pH 3 to 7, they are poorly exploited as coloring agents in food processing, being less commonly used than anthocyanins and carotenoids.¹⁰⁰  Besides betanin from red beet, cactus fruits and Amaranthaceae plants are good alternative sources.¹⁰¹  Cactus fruits from the genera Opuntia and Hylocereus are edible sources of betalain pigments. The color shade of the juice of Opuntia ficus‐indica cv. Rossa is similar to that of beet preparations, whilst the juice from Opuntia ficus‐indica cv. Gialla displays a yellow tonality and the juice from Hylocereus plyrhizus is characterized by purplish hues. The Amarantahaceae family is a rich source of diverse and unique betacyanins: eight amaranthine‐type, six gomphrenin‐type, and two betanin‐type pigments.³² 

Turmeric is an aromatic spice native to Southeastern Asia obtained from the dried ground rhizomes of Curcuma longa L., a perennial shrub that belongs to genus Curcuma of the Zingiberaceae family. Its dried ground rhizomes provide a bright yellowish‐brown powder also known as yellow ginger or Indian saffron.¹⁰² 

The compounds responsible for the yellow color of turmeric are known as curcuminoids. Turmeric also contains essential oils containing monocyclic monoterpenes, sesquiterpenes (bisabolanes and germacranes), arabinogalactans, and ar‐turmerone, which are responsible for aroma and taste. The three main compounds that comprise the pigmented curcuminoid complex are curcumin (1,7‐bis (4‐hydroxy‐3‐methoxyphenyl)‐1,6‐heptadiene‐3,5‐dione), demethoxycurcumin (feruloyl (4‐hydroxycinnamoyl) methane), and bisdemethoxycurcumin or bis(4‐hydroxylcinnamoyl) methane (Figure 1.7).¹⁰² 

There are three forms of coloring products based on Curcuma longa L. commercially available: turmeric powder, turmeric oleoresin, and purified curcumin. Turmeric powder is obtained from the grinding of dried rhizomes yielding a fine powder. Oleoresin is obtained from turmeric powder by solid–liquid extraction using ethyl acetate, acetone, dichloromethane, methanol, ethanol, or hexane as solvent. After filtration, the solvent is removed by evaporation or distillation resulting in an orange viscous oleoresin. Curcumin powder (E100) is an orange‐yellow crystalline powder obtained from turmeric oleoresin by crystallization.¹⁰²  Curcumin is an oil‐soluble pigment with a melting point of 174 °C. It is stable at acidic pH but readily decomposes at pH above neutral. It is light sensitive, especially in solutions, but highly stable to heat.

Turmeric is a very important herb due to its use in foods, cosmetics, and medicines. Turmeric powder is widely used as culinary ingredient due to its desirable orange‐yellow color and spicy flavor having well‐established application as coloring agent in mustard paste and curry powder. The oleoresin is generally added to oil‐soluble food products such as mayonnaise, fish, meat, soups, and non‐alcoholic beverages. On the other hand, curcumin powder is added to products where turmeric is incompatible due to its bitter‐peppery taste such as cheese, butter, confectionary, ice cream, and some beverages. Curcumin is also used as an antioxidant to prevent rancidity.¹⁰⁶  Many pharmacological properties have been attributed to curcumin, including cardiovascular protection, antitumor, antioxidant, anti‐inflammatory, anti‐Alzheimer, anti‐hepatotoxic, antibacterial, and antiviral activity.¹⁰⁴  Its unique bioprotective properties have been associated to neutralization of free radicals on the surface of skin, retarding aging and damage due to UV radiation.^103,105 

Flavors and fragrances are used in a wide variety of cosmetic, pharmaceutical, and edible products. Preference is usually given to natural products, but their shortage, high price, and price fluctuations are often the compelling reasons for partially, if not fully, switching over to synthetic equivalents. The rapid development of the fragrance and flavor industry in the nineteenth century was generally based on essential oils and related natural products. Essential oils produced from aromatic plants are formulated to make flavors and fragrances for a wide range of end uses, such as soaps, cosmetics, perfumes, toiletries, detergents, confectioneries, alcoholic and nonalcoholic beverages, ice creams, baked goods, convenience foods, tobacco products, aerosols, sprays, syrups, and pharmaceutical preparations.^106,107 

Essential oils have been known to mankind for millenniums. The history of production of essential oils dates back to 3500 years BCE when the oldest‐known water distillation apparatus made of burnt clay was employed. In 1480 BCE in Egypt, fragrant plants, oils, and resins were collected and used as ingredients for perfumes, medicines, flavors, and for the mummification of bodies. The use of essential oils as food ingredients has a history dating back to ancient times, with the use of citrus and other pressed (manually or mechanically) oils in sweets and desserts in ancient Egypt, Greece, and the Roman Empire. The fragrance used in the first alcoholic perfume in history was based on rosemary essential oil distillate and was created in the mid‐fourteenth century for the Polish‐born Queen Elisabeth of Hungary. The beginning of the eighteenth century saw the introduction of ‘Eau de Cologne’, based on bergamot and other citrus oils, which remains widely used to this day. While knowledge of the science of essential oils did not increase during the seventeenth century, the eighteenth century brought about only small progress in the design of equipment and in refinements of the techniques used. The beginning of the nineteenth century brought progresses in chemistry, including wet analysis and an increased development of hydro‐distillation methods. The nineteenth century is generally regarded as the beginning of the modern phase of industrial application of essential oils.^106,108 

The term ‘essential oil’ is a contraction of the original ‘quintessential oil’, a concept dating back to the Aristotelian idea that matter is composed of four elements (fire, air, earth, and water) and the fifth element, or quintessence, was then considered to be the spirit or life force. Distillation and evaporation were thought to be processes of removing the spirit from the plant.¹⁰⁹  Far from being spirit, essential oils are physical in nature, composed of complex mixtures that can contain hundreds of compounds. Nevertheless, they are usually characterized by two or three major components at fairly high concentrations (20–80%), while the rest of the components are present in trace amounts, but are still important in building the aroma.¹¹⁰ 

Essential oils are secondary metabolites that act in the protection of the plants, having antibacterial, antiviral, antifungal, and insecticide properties; they also act against herbivores by reducing their appetite for such plants. For these properties, essential oils have been largely employed in pharmaceutical, food, and cosmetic industries.¹¹¹ 

In the pharmaceutical industry, essential oils are widely employed to prevent and treat human diseases. As examples, essential oil from Eucalyptus species produces analgesic and anti‐inflammatory effects,¹¹²  that from nutmeg (Myristica fragrans) has a potent hepatoprotective activity against liver damage caused by certain chemicals,¹¹³  and that from Origanum onites L. has anti‐angiogenic and anti‐tumor activities.¹¹⁴  Essential oil of coriander (Coriandrum sativum) is used as carminative or as a flavoring agent to cover the bitter taste of other medicines.¹¹⁵  It has been extensively reported that essential oils can potentially be employed for the prevention and treatment of cancer¹¹⁶  and cardiovascular diseases, including atherosclerosis, by reducing plasma concentrations of cholesterol and triglycerides,¹¹⁷  and thrombosis, by inhibiting platelet aggregation and thromboxane formation.¹¹⁸  They are also used in pharmacy, balneology, massage, and homeopathy. Furthermore, the clinical use of their volatile constituents via inhalation, defined as aromatherapy, have expanded worldwide.¹¹⁹ 

Essential oils are known to possess potential application as food preservatives due to their antimicrobial properties against a wide range of microorganisms^120,121  present in a number of food products, such as meat and its products, fish, dairy products, vegetables, rice, and fruits.¹²²  Negi¹²³  presents a review about the stability, toxicity, and mechanisms of action of natural antimicrobials, including essential oil and plant extracts, for food application. More recently, many essential oils have been qualified as natural antioxidants,^124,125  but their use in foods is often limited due to flavor considerations. Anthony et al.¹²⁴  analyzed the antioxidant activity of 423 essential oils from 48 plant families and concluded that phenolic terpenes are major constituents of the most effective oils.

Despite their application for their biological properties, the greatest use of essential oils is as flavoring. The coriander oil (Coriandrum sativum L.) is used in the liquor, cocoa, and chocolate industries, besides being applied in various food products and in soap.¹²⁹  In the cosmetic industry the majority of essential oils are introduced into fragrance compositions. They are used in perfumes, aftershaves, cosmetics, air fresheners, and deodorizers. In recent years, the importance of essential oils as biocides and insect repellents has also increased.¹⁰⁸  Clove (Syzygium aromaticum) oil is traditionally used in dental care as a sealing component and as an antiseptic for mouth hygiene.¹²⁷  The Brazilian cherry tree leaves essential oil has been used by the Brazilian cosmetics industry for its astringent properties, which are associated with its pleasant smell. The main applications are in shampoos, hair conditioners, face and bath soaps, body oils, and perfumes.¹²⁸ 

Essential oils are volatile, liquid, and clear, are rarely colored, and are characterized by a strong odor. They are highly concentrated substances isolated from aromatic plants by several extraction methods; the most commonly employed are steam distillation and hydro‐distillation. The levels of essential oils found in plants can be anywhere from 0.01 to 15 wt % of the total. Essential oils are soluble in lipids and organic solvents usually with a lower density than that of water. Generally the major components determine the biological properties of the essential oils, but the synergistic effect with minor compounds should not be disregarded.

The first main group that composes essential oil is terpenes and terpenoids, and the other is aromatic and aliphatic constituents, derived from phenylpropane, which comprise aldehyde, alcohol, phenols, methoxy derivatives, and methylene dioxy compounds. Thus, essential oils are classified into terpenoids, shikimates, polyketides, and alkaloids.¹¹¹  There are a number of terpenoids, shikimates, and polyketides of importance in essential oils but very few alkaloids.

Polyketides and lipids have the simplest biosynthetic pathway. Polyketides are natural products whose biosynthesis can be traced to an intermediate that contains repeating ketide units. The biosynthesis of polyketides is similar to that of fatty acids. They are chemically diverse, but all plant‐derived polyketides are produced in the cytosol using enzymes called polyketide synthases, which catalyze the initial steps in polyketide formation via the condensation of a starter (usually acetyl‐CoA) and extender molecules (usually malonyl‐CoA), resulting in a chain with carbonyl groups.¹²⁹ 

There are three main paths by which components of essential oils and other natural extracts are formed in this family of metabolites: condensation reactions of polyketides, cyclization of arachidonic acid, and degradation of lipids. Condensation of polyketides leads to phenolic rings. The most important natural products containing polyketide phenols are the extracts of oakmoss and treemoss (Evernia prunastrii). The cyclization of arachidonic acid, a polyunsaturated fatty acid, plays a special role as a synthesis intermediate, for compounds such as prostaglandins and methyl jasmonate, in plants and animals.¹⁰⁹ 

The major metabolic route for fatty acids involves β‐oxidation and cleavage resulting in acetate and a fatty acid with two carbon atoms less than the starting acid, that is, the reverse of the biosynthesis reaction. Allylic oxidation followed by lactonization rather than cleavage leads to lactones. A wide variety of aliphatic entities are produced by the reduction of the acid function to the corresponding alcohols or aldehydes.¹⁰⁹  Some examples are shown in Figure 1.8.

Through photosynthesis, green plants convert carbon dioxide and water into glucose. Cleavage of glucose produces phosphoenolpyruvate, which is a key building block for the shikimate family of natural products. Shikimic acid is synthesized from the condensation of phosphoenolpyruvate and erythrose‐4‐phosphate, and thus its biosynthesis starts from the carbohydrate pathway. Its derivatives can usually be recognized by the characteristic shikimate pattern of a six‐membered ring with either a one‐ or a three‐carbon substituent on position 1 and oxygenation in the third, and/or fourth, and/or fifth positions.¹⁰⁹ 

Phenylpropanoids originate through the shikimic acid biosynthetic pathway. These compounds are found as the main component of essential oil of certain plants species, such as grass. The main phenylpropanoids and chemotypes are eugenol, methyl eugenols, myristicin, methyl cinnamate, elemicin, chavicol, methyl chavicol, dillapiole, anethole, estragole, and apiole.¹³⁰ Figure 1.9 shows some of them. The shikimate pathway, operational only in microorganisms and plants, is the precursor for amino acids (phenylalanine, tryptophan, and tyrosine), aromatic aldehydes (vanillin), and simple aromatic acids (gallic acid). Plant amino acids phenylalanine and tyrosine also formed via the shikimic acid pathway are deaminated, oxidized, and reduced to yield important aromatic substances such as cinnamaldehyde and eugenol.¹³¹ 

Terpenoids are the most common compounds in essential oils. They are substances composed of isoprene (2‐methylbutadiene) units. Figure 1.10 shows the structures of some terpenoids. They are synthesized from five carbon units of isopentenyl pyrophosphate and its isomer, dimethylallyl pyrophosphate. Mevalonic acid, made from three molecules of acetyl CoA, is the key starting material for the terpenoids. Phosphorylation of mevalonic acid followed by elimination of the tertiary alcohol and concomitant decarboxylation of the adjacent acid group gives isopentenyl pyrophosphate. Terpenoid structures will always contain a multiple of five carbon atoms when they are first formed, and they are classified depending on the number of these units in their skeleton. The components of essential oils of the majority of plants belong to hemiterpenoids (C₅), monoterpenoids (C₁₀), and sesquiterpenoids (C₁₅) families.^109,130 

The hemiterpenoids (C₅) consist of a single isoprene unit. They are the smallest plant terpenoids and can be formed directly from dimethylallyl diphosphate by terpenoid synthase activity.¹³²  Many alcohols, aldehydes, and esters with a 2‐methylbutane skeleton occur as minor components in essential oils. Esters such as prenyl acetate give fruity top notes to essential oils and the corresponding thioesters contribute to the characteristic odor of galbanum.¹⁰⁹ 

The monoterpenes are formed from the coupling of two isoprene units (C₁₀). They are the most representative molecules of the essential oils, constituting 90%. They allow a great variety of structures and have been classified according to their functional groups as well as based on their linear or cyclic nature.¹¹¹ 

Myrcene, geraniol, citronellol, fenchone, limonene, and menthol are widespread in nature. Some sources of myrcene are hops and most of the common herbs and spices. The oil of Monarda fistulosa contains over 90% geraniol and its level in palmarosa is over 80%; geranium contains about 50% geraniol and citronella and lemongrass each contain about 30%. Citronella and related species are used commercially as sources of geraniol. Rose, geranium, and citronella are the oils with the highest levels of citronellol. Fenchone occurs widely in fennel, cedar leaf, and lavender. Limonene is present in many essential oils but the major occurrence is in the citrus oils, which contain levels up to 90%. l‐Menthol is found in various mints and is responsible for the cooling effect of essential oils, the two most important sources being cornmint (Mentha arvensis) and peppermint (Mentha piperita).¹⁰⁹ 

The sesquiterpenes are formed from the assembly of three isoprene units (C₁₅). The extension of the chain increases the number of cyclizations, which allows a wide structural diversity. A few important skeletal types are farnesal, nerolidol, bisabolene, germacrone, vetinone, and caryophyllene.¹¹¹ 

Farnesol and nerolidol are the only known acyclic sesquiterpenoid alcohols. Farnesol was first isolated from Abelmoschus moschatus Moensch, but has also been obtained from numerous other essential oils.¹³³  α‐Bisabolol is the simplest of the cyclic sesquiterpenoid alcohols, found in many species as chamomile, lavender, and rosemary. It has a faint floral odor and anti‐inflammatory properties. Clove is the best‐known source of caryophyllene and α‐humulene (the all trans isomer). The ring systems of these two compounds are very strained, making them quite reactive chemically. Caryophyllene, extracted from clove oil as a by‐product of eugenol production, is used as the starting material in the synthesis of several fragrance ingredients.¹⁰⁹ 

Vetiver and patchouli are two oils of great importance in perfumery. Both contain complex mixtures of sesquiterpenoids, mostly with complex polycyclic structures. The major components of vetiver oil are α‐vetivone, β‐vetivone, and khusimol, but the most important components as far as odor is concerned are minor constituents such as khusimone, zizanal, and methyl zizanoate. Nootkatone is an isomer of α‐vetivone and is an important odor component of grapefruit. Patchouli alcohol is the major constituent of patchouli oil but, as is the case with vetiver, minor components are more important for the odor profile. These include nor‐patchoulenol and nor‐tetrapatchoulol.¹⁰⁹ 

Essential oils are present in various parts of the plant including seeds, roots, wood, bark, leaves, flowers, fruits, berries, rhizome, peel, and resin.

Anise oil is obtained conventionally by steam distillation from dry ripe seeds of anise (Pimpinella anisum L.) or star anise (Illicum verum Hook. f.), Apiaceae, but other techniques have been evaluated for better extraction performances, such as solvent extraction and supercritical fluid extraction.^134,135  The main constituent of anise essential oil is trans‐anethole, present to about 90–95%, followed by estragole (2.4%). Other constituents present in concentrations higher than 0.06% are (E)‐methyleugenol, α‐cuparene, α‐himachalene, β‐bisabolene, p‐anisaldehyde, and cis‐anethole. Anise oil is an established flavoring agent used in the manufacture of perfumes, toothpaste, and liquors. It is also used as food flavoring in fish, poultry, soups, ice cream, chewing gum, pickles, cake, sweet snacks, and alcoholic drinks.¹³⁶ 

The essential oil of nutmeg (Myristica fragrans), Myristicaceae, an important spice used for the flavoring of numerous food products, is composed of terpenes such as α‐, β‐, and γ‐pinene, sabinene, limonene, and 4‐terpineol. Other important components are safrol, elimicin, eugenol, and myristicin; the last one is responsible for the nutmeg characteristic aroma.¹³⁷  Some of these compounds have insecticidal properties. Nutmeg essential oil is also used as a component of certain types of perfumes and as a flavoring agent for dentifrices.¹³⁸ 

Seeds and fruits of the families Apiaceae, Piperaceae, and Myristicaceae usually require grinding up prior to steam distillation. In many cases, the seed has to be dried before comminution takes place.

The well‐known bark oils are obtained from birch, cascarilla, cassia, cinnamon, and massoia.¹⁰⁸  Cinnamon and cassia have long been held in high esteem as aromatics as well as ingredients of foods and perfumes. Their bark have an aromatic and sweet taste with a spicy fragrance. Cinnamaldehyde and the phenylpropenoid eugenol are the major constituent of cinnamon and cassia essential oils.¹⁰⁹  These oils are used in food, pharmaceutical, and perfume industries. They find extensive use in flavoring meat and fast food, sauces, pickles, baked foods, candies, confectionery, liqueurs, and soft drinks. In pharmaceutical preparations, bark oil is used to mask the unpleasant taste of medicines. It is also used to impart a woody and musky undertone to perfumes. However, the use of bark oil in the perfume industry is limited due to its skin sensitizing property.¹³⁹  Cinnamon leaf oil has a quite different flavor compared to bark oil. It has spicy cinnamon, clove‐like odor and taste, whereas cinnamon bark oil has a bitter flavor, is slightly pungent and burning. Eugenol is the main component of cinnamon leaf oil.¹⁴⁰ 

Wood oils are derived mostly from species of Santalum (sandalwood), cedar, amyris, cade, rosewood, agarwood, and guaiac. In order to achieve complete recovery of the essential oil, the wood has to be reduced to a very fine powder prior to steam distillation, but in some cases coarse chipping of the wood is adequate for efficient essential oil extraction.¹⁰⁸ 

Sandalwood oil has very good fixative properties and is very light in color, so it can be added without interfering in the ultimate coloration of products. It also has such a delicate aroma that it can be blended in small quantities without altering the dominant fragrance. It is used in soaps, cosmetics, incense, perfumes, and confectioneries. Conventionally, steam distillation is employed for recovering sandalwood oil, with a 3.8% yield after 24 h; liquid CO₂ extraction yields 4.9% oil in 2 h.¹⁰⁷  Santalols are the main components of sandalwood oil.¹⁰⁹ 

Rosewood oil is obtained from one of the species of the Lauraceae family, the Aniba rosaeodora Ducke. All parts of the tree are fragrant, although only the trunk wood is harvested and distilled. The oil is colorless to pale yellow with a woody‐floral fragrance. The main constituent of rosewood oil is the monoterpene alcohol linalool, which is an ingredient used in many fragrance compounds. It may be found in decorative cosmetics, fine fragrances, shampoos, toilet soaps, and other toiletries as well as in non‐cosmetic products such as household cleaners and detergents.¹⁴¹  Linalool is also used to create natural flavors, e.g. as a component of natural apricot flavor.¹⁴⁰ 

Camphor occurs in many essential oils in both enantiomeric forms. Its richest source is the oil of camphor wood (C. camphora. L. Sieb and a number of related varieties), but it is also an important contributor to the odor of lavender, sage, and rosemary.¹⁰⁹  Almost all the camphor oil is obtained by steam distillation of the wood (yield 2.2%). About 70% of camphor is removed from crude oil to give camphor oil. This oil is further fractionated to obtain three oils: white camphor oil (13% of the original oil: 46% 1,8‐cineole, 22% α‐pinene, 21% camphor), which can be rectified to result in an oil with some similarity to eucalyptus oil; brown camphor oil (14% of the original oil: 32% isosafrole, 14% safrole); and blue camphor oil (0.7% of the original oil: azulenes).¹⁴⁰ 

Ginger is one of the major spice essences with widespread use in food (sauces, soups, embedded food, bakery, and confectionery products), beverages, and medicines. Brown ginger is produced from unpeeled rhizomes, whereas white ginger comes from skinned rhizomes.¹⁴⁰  The major pungent constituents of ginger oil are the gingerols. The steam distillation cannot recover these pungent components because they are thermally degraded to shogaols, volatile aldehydes, or ketones. Industrially, ethanol, acetone, trichloroethane, and dichloroethane are used to recover gingerols. Another preferred alternative is CO₂ extraction when the ginger extract is intended to be used in high‐quality formulations. For use in soft drinks, CO₂ extracts offer both pungency and flavor in the most stable form and can be used for bottled syrup.¹⁰⁷  Furthermore, CO₂ extract is closer to the original raw material in terms of sensory characteristics.¹⁴² 

Ginger extract has also been used for over 5000 years in Asia for therapeutic purposes. It is indicated for the treatment of diseases of the gastrointestinal and respiratory systems, arthritis, cramps, dementia, infectious diseases, muscle pains, sprains, migraine, fever, hypertension, impotence, heart palpitations, rheumatism, and even cancer.^143–147 

Numerous leaves are used as source of essential oils. Among them, basil, oregano, rosemary, and pepper oils are the most important to food industries due to their spicy and herbal flavors.¹⁰⁶  Basil is an herbaceous plant cultivated as a culinary herb in Europe. The essential oil of basil is generally obtained by steam distillation or hydro‐distillation from the leaves of the plant. About 140 components of basil oil are known, mostly oxygenated monoterpenes and phenylpropane derivatives; the major compounds are methyl chavicol, linalool, 1,8‐cineole, and eugenol.¹⁴⁸  The oil is mainly used in seasoning blends but can be useful in small quantities in a wide range of natural flavors.¹⁴⁰ 

A rather interesting example of diversity is oregano, which counts as the commercially most valued spice worldwide. More than 60 plant species are used under this common name showing similar flavor profiles characterized mainly by cymyl compounds such as carvacrol and thymol.¹⁴⁹  Oregano oil is particularly rich in p‐cymene, which has also been identified in thyme oils.¹⁰⁹  The major component of thyme oil is thymol (37–55%). This oil is used in seasoning blends and in traces in many flavors.¹⁴⁰ 

Peppermint oil is composed primarily of menthol and menthone, but it is not used for the production of menthol due to its high price. The oil is used to give peppermint flavor to confectionery products, liquors, tobacco, cosmetics, toothpastes, other oral hygiene products, and bubble gum. It is also used in mint and herbal blends.¹⁵⁰ 

Eucalyptus oil is isolated from fresh or partially dried leaves. It has a characteristic camphoraceous odor and has a pungent, spicy, and cooling taste. Eucalyptus essential oil is commonly used in traditional medicine for its expectorant and balsamic activities. Although more generally associated with medicinal use, it is also used in perfumery; the main oil component, 1,8‐cineole (sometimes referred to as eucalyptol), contributes to its fragrance. Eucalyptus oil can also be used as a cleaning agent and as an insect repellent.¹⁵¹ 

The leaves of rosemary (Rosmarinus officinalis L.) are best known as a spice and flavoring agent but they are also reported as herbal remedy with antioxidant, anti‐inflammatory, anticarcinogenic, antidiuretic, and hepatotoxic protective properties.¹⁵²  The major components of its essential oil are α‐ and β‐pinene, camphene, and camphor. The main use of the rosemary oil is in seasoning blends.¹⁴⁰ 

The essential oils of leaves are removed by steam distillation or selective solvent extraction. Extraction with volatile organic solvents, such as hexane, petroleum ether, benzene, toluene, ethanol, isopropanol, ethyl acetate, acetone, water, etc., is also commonly used, but this process can co‐extract some undesirable components, depending on their polarity and on the solvent polarity.¹⁰⁷ 

Copaiba oil is an oleoresin obtained by tapping the trunk of the trees from several Copaifera L. species (Leguminoseae). It is extensively commercialized in Brazil as capsules or crude oil. Copaiba oil is characterized by its terpenic content; the major compounds are volatile sesquiterpenes like β‐caryophyllene, α‐copaene, and α‐humulene.¹⁵³  It is also rich in kaurenoic acid, a diterpene that has been shown to exert anti‐inflammatory, hypotensive, and diuretic effects in vivo and antimicrobial, smooth muscle relaxant, and cytotoxic actions in vitro.¹⁵⁴  The cosmetic industry uses copaiba oil in shampoos, capillary lotions, and bathing foams.¹⁵⁵ 

The characteristic fragrances of flowers are due to the presence of volatile essential oils in their petals. These oils may occur in a free form as in rose, or in a combined form (as glycosides) as in jasmine. The recovery of flavors and fragrances from flowers is crucial because of their short life span. Besides, due to natural enzyme reactions, there is a continuous change in the odor profile. The extraction of essential oils from flowers can be carried out by a variety of both old and new processes. Maceration and enfleurage are the most primitive methods used, but they are tedious, time‐consuming, and inefficient. Therefore, they have been replaced by the solvent extraction method or most efficiently, by supercritical fluid extraction.¹⁰⁷ 

Jasmine is only successfully extracted by solvent extraction, not by steam distillation. Like many flowers used in perfumery, the hot steam would alter and destroy the floral accords for which jasmine is so prized.¹⁵⁶  In France jasmine is traditionally extracted by enfleurage. The major component of jasmine oil is the benzyl acetate. Indole also makes a very significant odor contribution to it, but it also occurs in many other essential oils.¹⁰⁹  Jasmine enjoys extensive use in perfumery in a large variety of compositions for its intense, tenacious, warm, sweet‐floral note. Cosmetic and toiletry products also use its aromatic benefits. In the food flavoring industry jasmine is used in alcoholic and soft drinks and in a wide range of food products.¹⁵⁶ 

The essential oil extracted from the dried flower buds of clove, Eugenia caryophyllata L. (Myrtaceae), is used as a topical application to relieve pain and to promote healing and also finds use in the fragrance and flavoring industries, due to a characteristic clove‐like aroma and burning, spicy flavor.^{140,157–159}  The main constituents of its essential oil are eugenol (around 75%), eugenyl acetate, and β‐caryophyllene (10–15% each). In food industry, clove oil's main use is as flavoring, antimicrobial, and antioxidant agent.^160–168  It also has fungicidal, antiviral, antitumor, and insecticide properties, besides acting on gastrointestinal disorders and respiratory diseases, which favors its use in pharmaceutical applications.^{127,166–170} 

Lavender essential oil has been used for centuries for a variety of therapeutic and cosmetic purposes. It is usually produced by steam distillation, from both the flower heads and foliage, but the chemical composition differs greatly, with the sweeter and most aromatic oil being derived from the flowers. Major components are linalool (40%) and linalyl acetate (25%). The lavender products are mainly used in fragrances, for example, with combination with bergamot oil, in Earl Grey tea flavors, and they are also often used in aromatherapy or incorporated into soaps and other products as a pleasant fragrance or as an antimicrobial agent.^140,170 

Hop extracts are used by the brewing industry to give bitterness and aroma to beer. The major components of hop essential oil are hydrocarbon terpenes, of which the most abundant are the monoterpene myrcene and the sesquiterpenes α‐humulene and β‐caryophyllene. Although the terpenes comprise well over 90% of the total oil of a fresh hop, their importance as such to the flavor of beer is generally inconsequential, as they are all virtually water‐insoluble and have relatively high flavor thresholds. Amongst the sesquiterpenes, humulene in particular is a precursor to some oxygenated compounds that may positively influence beer flavor.¹⁷¹ 

Chamomile is a common flowering plant and a member of the daisy family. There are two types: German (Matricaria recutita) and Roman chamomile (Chamaemelum nobile). Major components of Roman chamomile are isobutyl angelate (30%), isoamyl angelate (12–22%), and other esters. German chamomile oil contains α‐bisabolol oxide (40%), farnesenes (20%), and chamazulene (6%), resulting in its characteristic blue color. German chamomile is much less useful in flavor terms than the Roman chamomile oil. The Roman chamomile oil is used in many natural fruit flavors, particularly apple, pear, peach, apricot, mango, and passion fruit.¹⁴⁰ 

Ylang‐Ylang (Cananga odorata) essential oil is derived from the flowers, and it is primarily extracted by water or water‐and‐steam distillation. This distillation is typically interrupted multiple times based on specific gravity, thereby yielding fractions of varying desirability and value from a perfumery perspective. This oil has a medium to strong initial aroma that is described as fresh, floral, sweet, slightly fruity, fragrant yet delicate. In general terms, it consists of sesquiterpene hydrocarbons, alcohols, esters, ethers, phenols, and aldehydes. Ylang‐Ylang oil is used topically as a sedative, antiseptic, hypotensive, and aphrodisiac. In addition, it is used in foods and beverages as a flavoring agent and in cosmetics and soaps as a fragrance.¹⁷² 

Limonene is naturally found in many essential oils, especially citrus fruit peel, such as bergamot, grapefruit, lemon, lime, and orange.¹¹⁹  Although the major component of the grapefruit oil is limonene (88–95%), nootkatone (0.2%) is the most important odor component;¹⁰⁹  other components are α‐ and β‐pinene (<12%), γ‐terpinene (<9%), and citral (geranial and neral,<3%). Its main use is in soft drinks and confectionery, to add juicy character.

Bergamot oil is a complex mixture of more than 300 compounds. Major components are limonene (30–45%), linalyl acetate (22–36%), linalool (3–15%), γ‐terpinene (6–10%), and β‐pinene (6–10%); minor compounds comprise geranial, neral, neryl acetate, geranyl acetate, and bergaptene.¹⁴⁰  The major use of bergamot is to impart citrus flavor to food, beverages, and confectionery. Bergamot oil was also a component of the original Eau de Cologne.

Orange oil is widely used in orange flavors and many other natural flavors. Lemon oil is also widely used in lemon and other natural flavors, such as pineapple, butterscotch, and banana, and can be mixed with other citrus oils, such as lime, orange, and grapefruit.¹⁴⁰ 

Citrus oils constitute the largest sector of the world essential oil production.¹⁷³  Cold expression is the process usually applied to recover essential oils from lemon, bergamot, and orange peels or when essential oils are highly thermolabile. In this process, oil cells are broken by rolling the peels in hollow vessels fixed with spikes on the inside surface for the abrasion of the peel, allowing the oil to ooze out from the outside surface in the form of an aqueous emulsion, which is subsequently centrifuged. Citrus oils obtained by this process have superior odor characteristics when compared to steam distilled oils, because of the non‐thermal processing. However, the unavoidable raise of temperature due to the mechanical friction in the process causes some thermal degradation, the result of which is that cold pressed oil is dark in color.¹⁰⁷ 

Roots are source of valerian oil. This perennial herb is indigenous to Europe and Asia. The main components are bornyl acetate (32–44%), camphene (16–25%), and α‐ and β‐pinene (6–12%). However, the most important flavor component is isovaleric acid (1–4%). The oil is used in many fruit flavors but at low levels.¹⁴⁰ 

Edible fats and oils are water‐insoluble substances that consist predominantly of glyceryl esters of fatty acids, or triglycerides, with some non‐glyceridic materials in small or trace quantities. The choice of the terms ‘fats’ and ‘oils’ is usually based on the physical state of the material at ambient temperature; fats appear solid and oils appear liquid.¹⁷⁴ 

The processing of edible fats and oils involves a series of stages in which both physical and chemical changes are made to the raw material. Processing is initiated by an extraction or rendering process to remove the fat or oil from the seed, bean, nut, fruit, or fatty tissue. The crude fats and oils recovered contain compounds responsible for the development of undesirable odors, flavors, and colors; therefore, several further steps of processing are carried out to remove the unwanted compounds.¹⁷⁵  After extraction, the processing of vegetable oil almost always includes neutralization or refining, bleaching, and deodorization. Rendered animal fats are normally clarified to remove impurities, bleached, and deodorized. Clarification, neutralization, bleaching, and deodorization are all purification processes which affect the flavor, flavor stability, and appearance of the fat or oil product while removing harmful impurities.¹⁷⁴ 

Fats and oils occur naturally in a wide range of sources, including oil seeds, fruit pulp, animals, and fish. Oil seeds are the major source for the production of edible oils; seeds specifically grown for the production of oil or protein include corn, soybean, canola, rapeseed, sunflower, palm, and olive. Other sources of vegetable oils include by‐products of crops grown for fiber, such as cottonseed and flaxseed, crops grown for food and their co‐products, such as corn germ, wheat germ, rice bran, coconut, peanuts, sesame, walnuts, and almonds, as well as non‐edible crops, such as castor, tung, and jojoba. Animal fats can be obtained from a variety of animal tissues, such as beef, chicken, pork, and fish. Examples of edible animal fats are butter, lard (pig fat), tallow, ghee, and fish oil. They are obtained from fats in the milk, meat, and under the skin of the animal. Fish oil is the lipid extracted from the body, muscle, liver, or other organ of the fish. Oils and fats can still be obtained from microbial products, algae, and seaweed. There are many physical and chemical differences among these diverse biological materials that define the characteristics of the individual fat or oil, which in turn determines the suitability of this ingredient in applications.^176–178 

Edible fats and oils are the raw materials for oils, shortenings, salad dressing, margarines, and other specialty or tailored products that are functional ingredients in food products prepared by food processors, restaurants, and at home. The major non‐food product uses for fats and oils are soaps, detergents, paints, varnish, animal feed, resins, plastics, lubricants, and fatty acids.¹⁷⁴ 

Shortening was originally the term used to describe the function performed by naturally occurring solid fats like lard and butter in baked products.¹⁷⁹  The term ‘bakery’ includes not only the production of bread, but also all food products in which flour is the basic material and to which heat is applied directly by radiation from the walls or top and bottom of an oven or heating device. Therefore, it includes the production of bread, cake, pastry, biscuits, cracker, cookies, pies, toppings, frostings, fillings, etc. Shortenings are very important ingredients for the baking industry because they comprise from 10% to 50% of most baked products. Their functions include: (1) imparting shortness, or richness and tenderness, to improve flavor and sensory characteristics; (2) enhancing aeration for leavening and volume; (3) promoting desirable grain and texture qualities; (4) providing flakiness in pie crusts, Danish, and puff pastries; (5) providing lubrication to prevent the wheat gluten particles from adhering together, which retards staling; (6) enhancing moisture retention for shelf‐life improvement; and (7) providing structure for cakes, icings, and fillings.¹⁷⁹  Today, shortening has become virtually synonymous with fat, and it includes many other types of edible fats designed for purposes other than baking.

Cocoa butter is the natural vegetable fat obtained through the crushing and grinding of cocoa beans. It contains glycerides of stearic, palmitic, and lauric acids. Cocoa beans are the source of two important ingredients of chocolate: cocoa powder and a solid fat called cocoa butter.¹⁸⁰  Besides, cocoa butter is a traditional emollient employed in several cosmetic products for skin, hair, and lips care; it is considered the most known and most stable butter of natural origin.¹⁸¹ 

The seeds of cupuassu, a Brazilian Amazonian fruit, contain high amounts of fat (around 60%) with digestibility and chemical and sensory characteristics similar to cocoa butter, although they have a different fatty acid profile. The seeds have a big potential to substitute cocoa in chocolate production.¹⁸²  In cosmetic products, cupuassu butter can be used as emollient to soften the skin. The seeds have not been widely explored and in most situations they are still used by farmer as animal feed.¹⁸³ 

Margarine was developed as a butter substitute. It is a flavored food product containing 80% fat and fortified with vitamin A. It is made by blending selected fats and oils with other ingredients such as milk, emulsifiers, preservatives, and coloring agents, to produce a table, cooking, or baking fat product that serves the purpose of dairy butter, but is different in composition and can be used for different applications.¹⁷⁴  Margarine production involves three basic steps: emulsification of the oil and aqueous phases, crystallization of the fat phase, and plasticification of the crystallized emulsion.¹⁸⁴  Over 10 different types of margarines are produced today, including regular, whipped, soft tub, liquid, diet, spread, no fat, restaurant, baker's, and specialty. These margarines are made from a variety of fats and oils, including soybean, cottonseed, palm, corn, canola, safflower, sunflower, lard, tallow, palm kernel, and coconut. Margarine products cater to the requirements of all the consumers: retail, food service, and food processor.¹⁷⁹ 

Liquid oils are usually identified by their physical state at ambient temperature and classified according to their functionality traits: cooking, salad, and high stability. Cooking oils are typically used for pan frying, deep fat frying, sauces, gravies, marninates, and other non‐refrigerated food preparations where a clear liquid oil has application. Salad oils are suitable for the production of mayonnaise or salad dressing emulsion and are stable at low temperatures. The high stability oils possess an exceptional oxidative or flavor stability, and are a clear liquid at room temperature.¹⁷⁴  The source of liquid oils available are canola, corn, cottonseed, olive, peanut, safflower, soybean, palm, sunflower, their blends, and some other specialty oils.

Sunflower oil is the non‐volatile oil extracted from sunflower (Helianthus annuus) seeds. It is commonly used in food as frying oil, and in cosmetic formulations as an emollient. Typically up to 90% of the fatty acids in conventional sunflower oil are unsaturated, namely oleic (16–19%) and linoleic (68–72%). Palmitic (6%), stearic (5%), and minor amounts of myristic, myristoleic, palmitoleic, arachidic, behenic, and other fatty acids account for the remaining 10%.¹⁸⁵  Sunflower oil also contains lecithin, tocopherols, carotenoids, and waxes. The three types of sunflower oils produced are high linoleic, high oleic, and mid oleic. High linoleic sunflower oil typically has at least 69% linoleic acid. High oleic sunflower oil has at least 82% oleic acid. Variation in fatty acid profile is strongly influenced by both genetics and climate.¹⁷⁸ 

Corn oil is the oil extracted from the germ of corn (maize) and is almost entirely used for food. Corn oil is regarded as exceptional in flavor and quality, with a healthy image for incorporation into processed foods, and also for snack food frying due to its high smoke point. It is also a key ingredient in mayonnaise and salad dressings.¹⁸⁰  Corn oil contains 9–17% palmitic acid, 20–42% oleic acid, and 39–63% linoleic acid. Refined corn oil is 99% triglycerides, with proportions of approximately 59% of polyunsaturated fatty acids, 24% of monounsaturated fatty acids, and 13% of saturated fatty acids.¹⁷⁸ 

Safflower oil is flavorless and colorless. It is used mainly as a cooking oil and for the production of margarine. It may also be taken as a nutritional supplement.¹⁷⁸  This oil exhibits the highest polyunsaturated level and polyunsaturated/saturated ratio levels commercially available. Its lack of wax, low free fatty acids, and low unsaponifiable levels allow it to be easily refined and deodorized. It contains low levels of phosphatides and unsaponifiables. The phospholipids included are phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl myoinositol, and phosphatidyl serine. The major fatty acid found in the phosphatides is linoleic acid, and the unsaponifiables are mostly sterols and terpenes.¹⁸⁶ 

Soybean oil is less expensive than corn, safflower, and sunflower oils, yet it has many of the desirable characteristics of premium vegetable oils: it has a high level of unsaturation compared to some other vegetable oils. Crude soybean oil contains approximately 95–97% triglycerides, formed by both saturated and unsaturated fatty acids. It contains a high concentration of polyunsaturated linoleic and linolenic acids.¹⁸⁷  Soybean oil stands out for its nutritional qualities, permanent supply, considerable economic value, and high functionality. It is an important source of natural lecithin, tocopherols, and phytosterols for pharmaceutical and food uses. This oil can be used as a solvent, a lubricant, and as biodiesel after suitable modification.¹⁷⁸ 

Olive husk is a solid residue derived from olive oil extraction. Its main constituents are water, oil, olive peel, and kernels. This residue contains fat levels in the range of 20–25%, which are recovered by treating olive husk with organic solvents, usually hexane. The crude olive husk oil must be refined to be edible. This oil is similar to olive oil and it is gaining importance in the food industry.^188,189  Refined olive and husk oils differ little in fatty acid composition; oleic acid is the main component, with minor but nutritionally relevant contributions from palmitic acid and the essential linoleic acid. Among the substances with antioxidant properties, the total phenols content has a strong positive contribution for the high stability (shelf‐life) of these oils, but they have a very different phenolic composition.¹⁹⁰ 

Grape seed oil has been applied in various fields from cosmetics to cooking. The oil has a relatively high smoke point, around 216 °C, and it can be safely used for cooking at high temperatures. Grape seeds have 10–20% oil and large amounts of vitamin E. The oil presents several benefits for human health, due to the high content of unsaturated fatty acids and antioxidant compounds like monomeric flavan‐3‐ols, phenolic acids, and oligomeric proanthocyanidins.^191–194  In the conventional extraction process, the seeds are pressed, and then extracted with n‐hexane, but the recovery of grape seed oil by supercritical technology as an alternative process, especially because of n‐hexane's high flammability and hazardous effects to human health, has recently been studied. Grape seed oil consists mainly of triglycerides, which are rich in unsaturated fatty acids such as oleic and linoleic acids.¹⁹⁵ 

Palm fruits from the Amazon region, belonging to the Arecaceae family, promise to be an alternative and abundant source of vegetable oils with high nutritional value. Palm oil is obtained by pressing the palm oil (Elaeis guineensis) fiber. It is one of the few vegetable oils relatively high in saturated fats. It contains almost equal proportions of saturated (palmitic 48%, stearic 4%, myristic 1%) and unsaturated acids (oleic 37%, linoleic 10%). Valuable by‐products obtained from palm oil are carotene, tocopherols and tocotrienols (vitamin E), and palm‐fatty acid distillate. Palm oil is reddish because it contains high amounts of α‐ and β‐carotene and it is very nutritious due to the high amounts of vitamin E.¹⁷⁸ 

Palm oil is used mainly for food purposes but also in cosmetic products, engine lubricants, and biofuel production.¹⁹⁹  Because it is semi‐solid at ambient temperature, it is a good natural hardstock for shortenings, margarines, vanaspati, and processed foods such as cream fillings, ice‐cream, filled milk, coffee whiteners, whipping creams, infant formula, dry soup mixes, and salad oil.¹⁹⁷ 

Buriti oil is extracted from buriti (Mauritia flexuosa) fruits, Arecaceae. This oil is composed mainly of fatty acids, tocopherols, and carotenes. The high concentration of monounsaturated fatty acids provides buriti oil with a high nutritional quality and blood cholesterol‐lowering properties. In addition, the low concentration of polyunsaturated fatty acids gives buriti oil high oxidative stability. The nutraceutical fraction of buriti oil consists of tocopherols and carotenes, which are natural antioxidants forming vitamin E and pro‐vitamin A, respectively.^198,199  Buriti is the richest known source of carotenoids.²⁰³  The high nutritional value of its oil makes it interesting for the food industry. Besides, it has also been frequently used in cosmetic production.²⁰⁰ 

Rice bran is a by‐product of rice milling that contains 15–20% oil by weight. Its oil is edible, it has nutritional value and a nut‐like taste; it finds use in cooking and nutritional applications. The major fatty acids in rice bran oil are palmitic, oleic, and linoleic acids, with smaller amounts of stearic and linolenic acids, and traces of other fatty acids. It also contains waxes (2–4%), which are esters of saturated fatty acids with saturated alcohols, monomethyl sterols, dimethyl sterols, and tocotrienols. The latter together with oryzanols impart high oxidative stability to rice bran oil.²⁰¹ 

Jojoba oil is not a typical oil consisting mainly of triacylglycerols; rather, it is a mixture of long‐chain esters containing small amounts of triacylglycerols and other materials such as phospholipids and tocopherols. Because of its properties, it has found large application in skin care products and cosmetics.²⁰¹ 

Wheat germ oil is extracted from the germ of the wheat kernel. It is rich in linoleic acid and also contains α‐linolenic, palmitic acid, and oleic acids. The oil shows high vitamin E activity, due to the high content of tocopherols. Wheat germ oil is particularly high in octacosanol as the main active component. Octacosanol is a 28‐carbon long‐chain saturated primary alcohol found in a number of different vegetable waxes. It can be used as a low density lipoprotein (LDL) control, as a protectant against atherosclerosis and hepatic injury progression, and as antiplatelet, anti‐ischemic, and antithrombotic agent, with good tolerance by the human body.^202–210  Extracts from wheat germ oil have beneficial effects on the physical performance of athletes, due to the octacosanol. As a cooking oil, wheat germ oil is strongly flavored, expensive, and easily perishable.^178,202 

Edible oils, non‐edible oils, wild oils, used cooking oils, and animal fats have been identified as possible raw materials to produce biodiesel. Soybean, palm, rapeseed, and sunflower oils are used in the industry; the majority of biodiesel produced worldwide is from rapeseed oil, with 84% of total production.¹⁹⁶  The biodiesel production from waste cooking oils is an effective way to reduce the raw material cost and to solve the problem of waste oil disposal.²¹¹  In spite of edible oils being a biodiesel feedstock, its use is significantly affected by the food‐versus‐fuel issue. Currently, more than 95% of the world biodiesel is produced from edible oil, which is easily available on large scale from the agricultural industry. However, continuous and large‐scale production of biodiesel from edible oil without proper planning may cause a negative impact to the world, such as depletion of food supply leading to economic imbalance. A possible solution to overcome this problem is to use non‐edible oils or waste edible oils.²¹² 

Essentially all foods and food ingredients play important sensory and nutritional roles providing color, texture, flavor, and nutrients (carbohydrates, proteins, fats, vitamins, and minerals), which are essential to growth, development, maintenance, and other physiological functions of the human body. In addition, some foods and food components may provide extra important functionality, imparting to food health benefits or desirable physiological effects beyond basic nutrition.²¹³  These foods and food components are called functional foods. The ADA (American Dietetic Association)²¹⁴  defines functional foods as ‘any food or modified ingredient that can provide beneficial effect beyond that provided by the nutrients it contains’.²¹⁵  A functional food must remain food and it must demonstrate its effects in amounts that can normally be expected to be consumed in the diet. It is not a pill or a capsule, but part of the normal food pattern.²¹⁶  In the last decades, nutritional sciences are advancing from the classical concepts of avoiding nutrient deficiencies to nutritional adequacy since there is increasing scientific evidence that consuming some foods and food components may have additional functional effects and may reduce the risk of disease and specifically contribute to maintain the state of health and well‐being.

On the other hand, nutraceuticals are health‐promoting compounds or products isolated or purified from food sources. The term ‘nutraceutical’ is often used to refer to a food, dietary supplement or biologically active compound that provides health benefits. A nutraceutical is defined as any substance that may be considered as a food or part of a food and provides medical or health benefits including the prevention and treatment of disease. Nutraceuticals may range from isolated nutrients, dietary supplements, and diets to genetically engineered ‘designer’ foods and herbal products. Examples are isoflavonoids isolated from soybean, fish oil capsules, herbal extracts, glucosamine, chondroitin sulfate, lutein‐containing multivitamin tablets, and antihypertensive pills that contain fish protein‐derived peptides.^217,218 

Functional foods are one of the most promising fields in the nutritional sciences. These foodstuffs are interesting from the consumer point of view with the prospect of maintaining health and preventing diseases by using natural foods as part of the usual diet, and also from the industry point of view, for the added value of the products. ²¹⁹  Public health authorities consider prevention and treatment with nutraceuticals a powerful instrument to maintain health and to act against nutritionally induced acute and chronic diseases, thereby promoting optimal health, longevity, and quality of life.^217,218  Bioactive functional ingredients can come from a variety of sources, including plants, animals, and microorganisms. Some lipid‐based materials, such as phosphatidylcholine and sphingolipids, can be recovered from all three of them. Plants provide the greatest variety of bioactive ingredients, especially terpenes and phenolics. The carbohydrates are also primarily found in plant‐based products. Amino acids, proteins, and peptides can come from plants, animals, or microbial fermentation. Many interesting bioactive peptides have been recovered from milk.

The major classes of bioactive ingredients found in functional foods and nutraceuticals are: polyunsaturated fatty acids (methylene‐interrupted polyenes, conjugated fatty acids, pinolenic acid, etc.); phenolic compounds, which comprise natural monophenols, flavonoids (flavonols, flavanones, flavones, flavan‐3‐ol, anthocyanins, isoflavones), phenolic acids, hydroxycinnamic acids, lignans (phytoestrogens), and tyrosol esters; terpenes that include carotenoids (carotenes and xanthophylls), monoterpenes, and saponins; phytosterols (β‐sitosterol, campesterol, stigmasterol, sitostanol, campestanol, etc.); tocopherols (vitamin E); betalains (betacyanins and betaxanthins); organosulfides (dithiolthiones, polysulfides, sulfides); indoles (glucosinolates/sulfur compounds); protein inhibitors; and other organic acids.^{14,111,220,221} 

One important class is terpenoids. Phenolics are also a major group; it is composed of extremely diverse compounds, which exert significant bioactivity. As examples, isoflavones from soybean are used to reduce LDL cholesterol, and anthocyanins and phenolic acids are strong antioxidants used to reduce the expression of proinflammatory genes in in vitro systems. Carbohydrates generally deliver fiber, which enhances digestive health. Still in the gastrointestinal system, prebiotics are fermented by the gut flora, resulting in the production of short‐chain fatty acids in the colon. Probiotics, on the other hand, contain microorganisms that when ingested may help to establish a healthier gut flora.

Phytochemicals may be present in indigenous plants or crops (food), spices, seaweed, fungi, lichens, mosses, and microorganisms. In plants, they can be found in fruits, berries, seeds, leaves, needles, stems, branches, roots, bulbs, flowers, barks, buds, shoots of wood, etc.^14,222 

The polyunsaturated fatty acids (PUFAs) contain more than one double bond in their structure. PUFAs can be classified in various groups by their chemical structure: (1) methylene‐interrupted polyenes; (2) conjugated fatty acids; and (3) other polyunsaturates. The methylene‐interrupted polyenes comprise the ω‐3 essential fatty acids (hexadecatrienoic acid, α‐linolenic acid, stearidonic acid, etc.), ω‐6 fatty acids (linoleic acid, γ‐linolenic acid, eicosadienoic acid, etc.), and ω‐9 fatty acids (oleic acid, erucic acid, mead acid, etc.). The conjugated fatty acids have two or more conjugated double bonds, like linoleic acids (rumenic acid) and linolenic acids (β‐calendic acid). Pinolenic acid and podocarpic acid are examples of other polyunsaturates.

Currently, the consumption of products naturally containing PUFAs, such as fish, has decreased; these changes in food habits of the industrialized countries may be related to the increased rates of many diseases related to inflammatory processes. Some studies show that consuming food products containing ω‐3 fatty acids can alleviate symptoms of several psychiatric disorders.^223,224  The biological effects of ω‐6 fatty acids are used to develop pharmaceutical drugs and treatments for atherosclerosis, asthma, arthritis, vascular disease, thrombosis, inflammatory‐immune processes, and cancer.^225,226  Unlike the ω‐3 fatty acids, the ω‐6 and ω‐9 fatty acids are not classified as essential fatty acids because they can be synthesized by the human body from unsaturated fat.²²⁷ 

With respect to the conjugated fatty acids, linoleic acid is distinguished by its importance in the manufacture of quick‐drying oils, which are useful in oil paints and varnishes. Linoleic acid has also become increasingly popular in the industry of beauty products because of its beneficial properties on skin, in the pharmaceutical industry as an anti‐inflammatory and acne‐reducing agent, and in the food industry for its antioxidant effects on natural phenols.^228,229 

The phytosterols and phytostanols, the saturated form of phytosterols, are steroidal compounds similar to cholesterol, but from plant origin; they vary only in their carbon side chains and/or presence or absence of a double bond. Vegetable oils and products containing them can be rich sources of phytosterols. Grain products, vegetables, fruits, and berries are not as rich in phytosterols as vegetable oils, but they can also be significant sources of phytosterols due to their high consumption, reaching 150–450 mg/day. Most common phytosterols in the human diet are β‐sitosterol (65%), campesterol (30%), and stigmasterol (3%). Over 200 stanols have been identified, and the most common in the human diet are sitostanol and campestanol, which combined constitute about 5% of dietary phytosterols.^230,231 

Free phytosterols extracted from oils are widely used in fortified foods and dietary supplements. Commercially available products containing plant sterols and/or stanols in their free forms and ester type include margarine, yoghurt, yoghurt drinks, and orange juice. As tablets and capsules, they are particularly attractive because of the ease of incorporating these in a regimen of cholesterol reduction when compared to diet.^232–234  The plant sterols and stanols are known to reduce low density lipoprotein (LDL) serum cholesterol levels, and foodstuffs containing such compounds of plants are widely used as a dietary therapeutic option to reduce plasma cholesterol and the risk of atherosclerosis. However, recent evidence suggests that phytosterols/phytostanols may regulate proteins involved in cholesterol metabolism in both hepatocytes and enterocytes, although its effects have not been proven to reduce cardiovascular disease risk or overall mortality.^235,236 

Tocos comprise a class of chemical compounds that comprise various methylated phenols and from which many have vitamin E activity. Four tocopherols and four tocotrienols compose vitamin E. Both tocopherols and tocotrienols occur in groups of four (α, β, γ, δ) lipophilic antioxidants synthesized by photosynthetic organisms (Figure 1.11). The tocopherols occur mainly in seeds and leaves of plants. The seed oils (olive, sunflower, corn, and soybean) contain high concentrations of γ‐tocopherol and leaf lettuce contains high concentration of α‐tocopherol.^237–239 

The vitamin E form preferentially absorbed and accumulated in the human body is α‐tocopherol. This form is available in foods of the every day diet, such as vegetable oils, grains, peanut, corn, poppy seeds, asparagus, oat, chestnut, coconut, tomato, walnut, carrot, and goat milk.²⁴⁰  α‐Tocopherol has numerous biological properties; however, it causes indigestion, thus its bioavailability in the intestine is affected. Therefore its consumption as nutritional supplements in the form of tocopherol succinate and tocopherol acetate is indicated.²⁴¹ 

In general, tocopherols and tocotrienols are fat‐soluble antioxidants that may have many biological functions, such as relieving stress situations and premenstrual tension, preventing cellular damage, improving blood circulation, tissue regeneration, and intermittent claudication, among others. Additionally, the antioxidant activity of tocopherols is associated with inhibition of membrane lipid peroxidation and the elimination of reactive oxygen species.²⁴²  Vitamin E (α‐tocopherol) is also recognized for preserving fertility in mammals.^243,244 

Ginseng is a slow growing perennial plant with fleshy roots that has two large genera: Panax (Panax quinquefolius L., Panax ginseng CA Meyer), also known as Asian Ginseng, and Pfaffia (Pfaffia iresinoides, Pfaffia glomerata, and Pfaffia paniculata), known as Brazilian Ginseng. Ginseng is found mainly in the Northern Hemisphere and eastern Asia, usually in colder climates. Among the countries of South America, Brazil stands out as the most important center for the cultivation of plants of the genus Pfaffia.^245–247 

The dried root of Panax ginseng species contain saponins as active ingredients, called ginsenosides. In the case of Pfaffia species the main compounds are sitosterol, stigmasterol, allantoin, pfaffic acid, and pfaffosides A, B, C, D, E, and F.²⁴⁸  The chemical structures of ginsenoside and pffafic acid are shown in Figure 1.12.

Ginseng is marketed in energy drinks, tea, or capsules containing powdered root, mixed or not with ethanol extracts of these plants.²⁴⁹  The use of ginseng as a dietary supplement is related to its medical properties: improving physical and mental performances, especially by relieving symptoms of endocrine, immune, cardiovascular and central nervous systems.^250,251  The Brazilian Ginseng is marketed for the same purposes as Asian Ginseng, except that the bioactive compounds responsible for its invigorating properties belong to a different class, pfaffosides, as opposed to ginsenosides in the case of Asian Ginseng. Brazilian Ginseng acts as a cell regenerator, and it is indicated for physical and mental exhaustion and for treatment of circulatory irregularities, stress, anemia, diabetes, etc.^252,253 

In the plant kingdom, there are four main groups of bioactive compounds: nitrogenous substances, sulfurous substances, terpenes and phenolics. Carotenoids belong to the terpenes. They have been discussed for their coloring properties (see Section 1.2.1), but they also present extremely important biological properties.²⁵⁴  The carotenoids are the main dietary source of vitamin A precursors, especially in poorer countries. Although β‐carotene is the main compound with pro‐vitamin A activity, any carotenoid with at least one unsubstituted β ring, such as α‐carotene and β‐cryptoxanthin, have the added advantage of being able to be converted to vitamin A.⁴⁰  Furthermore, the interest in carotenoids has been increasing due to epidemiological studies that strongly suggest that consuming carotenoid‐rich foods reduces the incidence of several diseases such as cancer, cardiovascular diseases, age‐related macular degeneration, cataracts, diseases related to low immune function, and other degenerative diseases.^10,37,40,41  The antioxidant properties of carotenoids have been suggested as being the main mechanism by which they afford their beneficial effects.

Although more than 700 carotenoids have been identified in nature only 20 have been identified in human blood and tissues. At about 90% of the carotenoids in the human diet and body are β‐ and α‐carotene, which are commonly found in yellow‐orange vegetables and fruits; α‐cryptoxanthin is present in orange fruits; lutein is provided by dark green vegetables; and lycopene is obtained from tomatoes and its products.¹⁰ 

Even though lycopene is a carotenoid with no pro‐vitamin A activity⁷¹  it is an important antioxidant and free radical scavenger.⁷⁰  Due to its 11 conjugated and 2 non‐conjugated double bonds, it was found to be a more efficient antioxidant (singlet oxygen quencher) than β‐carotene, α‐carotene, and α‐tocopherol.⁷⁶  Lycopene plays an important role in human health through the protection against many degenerative diseases such as cancer, atherosclerosis, cataracts, and age‐related macular degeneration, as well as to premature aging.⁷⁰  Processed foods are frequently fortified with carotenoids such as lycopene to increase their nutritive value and/or enhance attractiveness.⁷² 

The quality of paprika is evaluated according to the red color intensity and to its pungency. Its degree of pungency originates from the group of components called capsaicinoids. They are vanillylamides of branched fatty acids, with 9–11 carbons, of which capsaicin (vanillylamide of 8‐methylnona‐trans‐6‐enoic acid) and dihydrocapsaicin (vanillylamide of 8‐methylnonanoic acid) occur in quantities higher than 80%.⁵³  They play an important role in human health as antibacterials, antioxidants, and immunoenhancers, helping to prevent cancer, cardiovascular diseases, age‐related macular diseases, degeneration, cataracts, diseases related to low immune function, arthritis, cystitis, and other degenerative diseases.^40,53  Furthermore, of the paprika carotenoids, β‐carotene and β‐cryptoxanthin also have pro‐vitamin A activity.²¹ 

Phenolics are a diverse group of aromatic secondary plant metabolites that are widely distributed throughout the plant kingdom. They originate from phenylalanine and, to a lesser extent, from tyrosine.²⁵⁵  They comprise compounds that possess at least one aromatic ring bearing one or more hydroxyl groups.²⁵⁶  Phenolic compounds can be divided into at least 10 different classes depending on their chemical structure, which basically include phenolic acids (simple phenols) and polyphenols (complex phenols), depending on the number of phenol subunits attached to it. Phenolic acids possess just one phenol subunit, comprising thus low molecular weight compounds. Polyphenols possess two or more phenol subunits including intermediate (flavonoids) or high (hydrolysable or condensed tannins, stilbenes, and lignans) molecular weight compounds.²⁵⁶ 

Phenolic acids are widely represented in plant kingdom. They are mainly located in the cell wall of plants and their main sources are fruits and vegetables.²⁵⁷  Two classes of phenolic acids can be distinguished: the hydroxybenzoic (HBA) and hydroxycinnamic acid (HCA) derivatives. The hydroxycinnamic acid derivatives are aromatic compounds with a three‐carbon side chain (C6–C3); p‐coumaric, caffeic, and ferulic acids are the forms that occur most frequently, usually as simple esters with hydroxy carboxylic acids or d‐glucose. On the other hand, the hydroxybenzoic acids have in common the C6–C1 structure, and include p‐hydroxybenzoic, gallic, and ellagic acids; they are presented mainly in the form of glucosides.²⁵⁸ 

Polyphenols possess two or more phenol subunits including intermediate (flavonoids: anthocyanins, flavonols and flavones, flavanones, chalcones and dihydrochalcones, isoflavones, and flavanols) or high (hydrolysable or condensed tannins, stilbenes, and lignans) molecular weight compounds. The polyphenols are also generally divided into hydrolyzable tannins, which are gallic acid esters of glucose and other sugars and phenylpropanoids such as lignin, flavonoids, and condensed tannins. The phenol substructures of polyphenols have various further nomenclatures depending on the number of phenolic hydroxyl groups (Figure 1.13).

The main sources of polyphenols are berries, tea, beer, grapes/wine, olive oil, chocolate/cocoa, nuts, peanuts, pomegranates, yerba mate, and other fruits and vegetables. Obviously, each matrix type has a different polyphenol composition and concentration. As an example, whilst hydroxycinnamic acids are the main polyphenolic compounds in coffee, they also exist in tea, although at lower concentrations.^259,260  The dominating polyphenolic compounds found in tea are flavonols or flavones.^261,262  The polyphenol compounds of mate tea can be used as natural antioxidants to increase the shelf‐life of various foods, processed and unprocessed, suggesting that the incorporation of polyphenolic extracts of yerba mate in foods can improve their nutritional and sensory quality as well as extending their shelf‐life. The seeds of cocoa are known to be rich in flavanol monomers (+)‐catechin and (–)‐epicatechin and procyanidin oligomers.^263,264 

Among the bioactive compounds commonly found in foods, phenolic compounds are amongst the most studied due to their antioxidant properties. There are several reasons for this interest, including the increasing knowledge about reactive oxygen and nitrogen species, the definition of predictive markers for oxidative damage, new evidence linking chronic diseases and oxidative stress, and growing data supporting the idea that some of the health benefits associated with fruits, vegetables, and red wine consumption may be linked to the polyphenolic compounds they contain.^264–271 

The potential of soybeans as a functional food is being currently explored. Indeed, soybeans and soy foods like soymilk, tofu, and miso are widely promoted and consumed based on assumed relationships between their ingestion and beneficial health effects in humans, including chemoprevention of breast and prostate cancer, osteoporosis, cardiovascular diseases and as a reliever of menopausal symptoms. The basis of this relationship includes the evidence provided by both epidemiological studies showing a lower incidence of these health conditions in Asian countries like Japan and China, where soybean and its derivatives are widely consumed, and intervention studies.²¹⁹ 

Several classes of phytochemicals have been identified in soybeans, including protease inhibitors, phytosterols, saponins, phenolic acids, phytic acid, and isoflavones.^272–275  The isoflavones are particularly noteworthy because soybeans are the only significant dietary source of these compounds. Isoflavones are a subclass of flavonoids that are also described as phytoestrogen compounds, since they exhibit estrogenic activity (similar effects to estradiol hormones). The basic characteristic isoflavone structure is a flavone nucleus, composed by two benzene rings (A and B) linked to a heterocyclic ring C (Figure 1.14). The benzene ring B position is the basis for the categorization of the flavanoid class (position 2) and the isoflavonoid class (position 3). The main isoflavones found in soybeans are genistein, daidzein, glycitein, and their respective acetyl, malonyl, and aglycone forms.^276–278 

Isoflavones are being extensively studied because of in vitro and in vivo biological activity consistent with the potential health effects associated with the consumption of soybeans. There is indication that isoflavones, at least in part, may play a role on the effects of soy foods on improving health.^279–284 

However, the mechanisms are not yet fully understood and may depend on several factors. The prevention of cardiovascular diseases by soybeans, for example, may depend on the concentration of bioactive components (such as isoflavones), processing and storage conditions of soybeans and foods, the amount, frequency and for how long they are consumed, individuals’ genetics and metabolism, among other factors. These factors interact and may directly or indirectly determine an effective reduction of cardiovascular disease risk on a specific subject. At the present time, the scientific data available is solid enough only to point to a possible relationship between soybeans and reduced cardiovascular diseases risk. Isoflavones are also being studied for the relief of menopausal symptoms and as hormone replacement therapy. Although there is no conclusive scientific evidence that isoflavones (or soybeans in natura) have positive health effects for the general population, they are increasingly being used as additives in milk and soy beverages and commercialized as nutritional supplements with an important market volume.

In this chapter we tried to present the most important and useful applications of natural products in order to illustrate their importance. Extraction processes affect the composition and bioactivity of the extracts; that is why it is so important to understand the mechanisms involved in the extraction processes. This and other aspects will be covered in the next chapters. But it is important to highlight that most techniques discussed in the next chapters may undoubtedly be used to extract the phytochemicals presented in this chapter from their natural sources.

The authors acknowledge the financial support from CNPq (project 2009/17234-9 and 2010/08684-8) and FAPESP (project 12/10685-8 and 11/19817‐1). The authors also acknowledge the contribution of Matheus A. Gigo (FAPESP 2012/11561‐0) and Roberta C. C. Celestrino (FAPESP 2012/11459‐1) in the revision of the references of this manuscript.