CHAPTER 1: Olive Origins

In this chapter, we start by outlining the history of olive trees and their important role in the development of human civilization in the Mediterranean. Ancient Greek, Roman, Jewish, Christian, and Islamic writings pay homage to the olive tree and describe how critical it is in providing food, heat, and light necessary for survival. The near immortality of the trees connects them with the ancient gods whose own immortal existence is mirrored in ancient trees such as the one shown in Figure 1.1. We will take you with us to excavations from Neolithic villages, where we can see that our ancestors used olive wood in their campfires, and to archeological sites of the bustling Bronze Age city of Klazomenai, where the pressing of olives at a communal olive press used a clever system of rock hewn holding tanks for separating the oil from the fruit liquor.

While we typically think of warm Mediterranean countries whenever olive oil is mentioned, we now understand that olives can be grown throughout the world in the “olive belt” of about 30° to 45° latitude in both the Northern and Southern hemispheres as long as the land is sufficiently dry.¹  In places like Spain, Italy, Greece, Turkey, and Tunisia, the “Old Olive World,” new commercial groves with millions of trees and modern presses stand next to family groves of several hundred trees that can be many hundreds of years old and village presses that were built at the turn of the last century. In the Mediterranean, many people either own their own groves or know someone who does. Most people who live in the country will have an olive tree or two in their garden. They may have consumed olive oil all their lives without ever having bought any! In general, consumers have very strong ideas about the way things should be done and how olive oil should taste. Modern agricultural practices can sometimes clash with the cultural olive heritage of the Old Olive World. By contrast, new groves and presses in areas like California, Australia, New Zealand, South Africa, and Argentina exist in the absence of that tradition. While some of the earliest European settlers in these former colonies brought olive trees with them, no substantial olive industry developed here until the end of the 20th Century. Today, in these “New Olive World” countries, groves of a million or more trees are harvested and transported within hours to modern facilities where they are processed using state of the art centrifugation methods. Perhaps the vision statement for the South African Olive Association “Old World Ideals with a New World Vision” best captures the contrast.

Today, it is very difficult to create quality olive oil in bulk without a team of dedicated people who plant, prune, and fertilize the trees, prepare the soil, harvest at the right time with the right equipment, deliver the fruit to the press in as timely a way as possible, process the fruit with respect for the natural goodness, bottle the oil with great care to preserve the quality and minimize degradation, perform chemical tests to ensure that the oil meets the highest standards, ship the oil according to accepted protocols, and store and sell the oil with the interests of their consumers in mind. As this book takes you through each of these stages in olive oil production, it will introduce you to a contemporary olive oil expert from around the world whose knowledge, vision, resourcefulness, and enthusiasm is emblematic of the hundreds of thousands of professionals who cooperate to bring the world’s best olive oils to your tables. These individuals have helped us to understand the links between history, quality, production, and processing.

Since the soul of the oil is made from the molecules that compose it, each chapter will also feature a particular molecule or molecules that best represent the ongoing development of the olive from grove to table. We will start in this chapter with triolein, the molecule that makes up the bulk of the oil itself and then, in later chapters, introduce you to the important and unique molecules that are present in smaller quantities but are responsible for the wonderful flavors, fragrances, and health effects. Introducing these natural compounds allows us to provide a richer explanation of the techniques of growing and processing, as well as of the impact on humans such as taste and smell, and can be proven to be responsible for the many health benefits of olive oil.

Most of all, we hope the readers will finish with an appreciation for the extraordinary effort required to make a high-quality EVOO (extra virgin olive oil), an understanding of what makes a good quality oil, and an increased resolve to include more of it in their daily life.

Ancient Islamic, Judaic, and Christian texts refer to the olive tree and olive oil as sacred. Olive imagery has been captured in many cultural traditions²  and great writers and thinkers from Homer, Hippocrates, Columella, and Pliny all wrote of its almost magical healing and anointing properties. Mustafa Kemal Atatürk, founder and first president of the Turkish Republic, was an advocate for modern olive production.³  Even Thomas Jefferson, one of the founding fathers of the USA, believed in the beneficence of the olive tree. Let’s see what has been said about the origins of the olive tree and the utilization of its wonderful oil in and out of the kitchens of our forefathers.

The first origin story for the olive tree comes to us from the early Judeo–Christian tradition as documented in the 1st Century manuscript on the Penitence of Adam from the Vita Adam. At the end of his life, Adam sent his third son Seth back to the Garden of Paradise to request the oil of divine mercy promised to him by God for his own redemption and that of humanity. Instead, the Angel guarding the gate gave Seth three seeds from the Tree of Life (or the Tree of Knowledge). Instructions were given to put the seeds in Adam’s mouth upon his death and bury them along with his body. When the time came and Adam died, Seth followed the Angel’s instructions and buried his father along with the seeds. A short time later, three saplings (or one tree with three branches) grew from the burial site. Though texts differ on the eventual destiny for the tree(s) at least one story has the trees growing into a cypress, a cedar, and an olive tree – three classic trees of the Middle East.⁴  According to one 15th Century text, the wood from these sacred trees grown out of the flesh and bones of Adam later become the rod of Moses and the cross on which Jesus was crucified.⁵  Figure 1.2 captures images of this story of the origins of these three trees from a 15th Century Italian fresco, a 15th Century Dutch woodcut and a modern photographic installation in Israel.

So, the olive tree appears as a gift from God to these humans, and represents a promise of his mercy and steadfast love. The Old Testament of the Christian bible makes more than 100 references to olive trees, olive oil, and olive branches. Perhaps most familiar is the olive branch brought back by a dove to the Ark and given to Noah to let him know that the floodwaters had receded (Genesis 8:11). With the branch came a promise – a covenant – that God would never again repeat this total destruction.

The use of olive oil for religious anointing is a frequent reference as is its use as a source of light against the darkness.

The New Testament holds a similar symbolic importance for the olive tree. On the night before he died, Christ retreated with his disciples to the Mount of Olives and was later captured close to the local olive press at Gethsemane (Mark 14:26–32). In Romans 11:17–24, the apostle Paul discusses grafting of wild saplings onto strong olive root stock and uses this as a metaphor for God’s cultivation of his people, seeking always the fruit of kindness.

Greek mythology contains another version of the origin of the olive tree. Here, it is linked to the warrior goddess Athena, daughter of Zeus.^6,7  The legend speaks of a contest designed by Zeus to be held for the gods. Each contestant was to prepare a special gift for the people of a city in Greece and the inhabitants of that city would review the offerings and choose the most perfect gift. The god who designed this gift would in turn be honored by having the city bear his or her name – thus guaranteeing the devotion and loyalty of its inhabitants for all times. On the day of the contest, two gods presented their gifts to the people of the city. First, Poseidon, god of the sea, struck the ground with his trident and out of the earth sprang a horse (some versions say a fountain). Next, Athena used her spear to strike the earth and the first olive tree instantly sprang forth. Since the olive tree was capable of producing light, heat, food, and shelter, the inhabitants of the city chose Athena’s gift. The city, Athens, bears her name even to this day. Figure 1.3 shows a photograph from the Parthenon in Athens depicting the contest for naming rights to the ancient city. An olive tree which, like its creator, is (nearly) immortal stands close to the corner of the Parthenon today.

Olive oil was a staple in Greek households and in their imaginations. More than 20 references are made to olive related items in Homer’s work.⁷  In The Iliad, he describes some of its non-culinary uses. It was a critical ingredient in the goddess Hera’s toilette as she set about preparing herself for her husband Zeus. Meanwhile Aphrodite anointed the body of the slain Trojan warrior prince Hector with scented olive oil. The Odyssey also contains references to olive oil’s place as a treasure to be stored with gold and bronze. Perhaps most poignant is Homer’s description of the wedding bed made by Odysseus for his beloved Penelope.⁸  One leg of the bed is made from a living olive tree, symbolizing perhaps their steadfast and timeless love. In a clever device to test the returning Odysseus – gone for 20 years – Penelope loudly orders a servant to move the bed to ready it for the man claiming to be her husband. When Odysseus shouts out that the bed cannot be moved because it is made of a live tree, Penelope knows the man standing in front of her is truly her long lost husband and they are joyfully reunited.

Hippocrates believed that olive oil was “the great healer.”^7,9  He was aware that a topical application of the oil would help relieve pain from skin abrasions and burns and he recommended it be massaged into wounds to help them heal quickly. Extracts of plants steeped in olive oil were used to provide relief from many gynecological diseases, and its use was recommended in curing infections of the ear, nose, and throat. Olive oil itself was massaged into aching muscles and its ingestion was recommended in small quantities to settle an upset stomach and in larger quantities as an emetic. Plants from celery to fennel to St John’s Wort to juniper were steeped in olive oil and used to preserve youthful healthy skin.

Columella was a naturalist writer of Roman times whose complete work was thought to be lost to time until a 12 volume combined encyclopedia De Re Rustica was found in the library of a Swiss monastery in the 15th Century. Book 7 contains thorough instructions for olive trees with regard to the ground soil preparation, grove locations, pruning, and fertilizing. A complete description of how and when to press olives is given in Book 12, Chapter 50.

Today, these words would be precisely the same instructions given to an olive farmer who desires to make the highest quality extra virgin olive oil. Pick when the olives are partly turned, be gentle with the fruit, and get the fruit to the press as soon as possible.

Pliny the Elder, the prolific 1st Century Roman writer, spends much ink describing the best methods for the cultivation of olive trees, the pressing of olive oil, and the many medical uses of the olive oil itself. His contrast of olive oil and wine is quite insightful.¹⁰ 

Pliny also repeatedly recommends: “Do not shake and beat your trees. Gathering by hand each year ensures a good harvest.”

In the Angel Gabriel’s revelations to the Prophet Mohammed, the majesty of Allah is said to be like a light that burns, as in Figure 1.4, from the oil of the blessed olive tree. Unlike that oil, Allah needs no fire to provide illumination.

This verse has been much analyzed by great Islamic philosophers such as Razi (ibn Zakariya al-Razi) in the 9th Century and Avicenna (ibn Sina) in the 11th Century.¹¹  Their ideas about divine illumination, “Light upon light,” and the majesty of Allah use this text as a touchstone.

Dimitri Gutas, Professor of Arabic and Graeco-Arabic at Yale University, has pointed out to us how important scholars of the Islamic golden age between the 10th and 14th Centuries, such as Avicenna and Ibn Qayyim al-Jawziyya, refer to earlier pharmacological knowledge of the time about the importance of olive oil. After referring to the verse above, they write: “Eat olive oil and anoint yourselves with it, for it is from a blessed tree.”¹²  The ascription of these recommendations to the Prophet Mohammed makes the advice much more authoritative in the eyes of Muslims.

Before he was President of the United States, Thomas Jefferson travelled throughout Western Europe, in part to explore agricultural markets and opportunities and to try the mineral waters for the restoration of an injured right wrist.^13,14  It was spring in southern France when he first encountered an olive tree in full blossom. From that point forward, he noted in careful detail the places where olive trees were planted. His travelling journals and later letters from Paris described his enchantment with the olive tree and his hopes to establish a grove of trees in South Carolina and Georgia. He dreamt that olive trees could provide ongoing nourishment for the poor – in particular the African slaves whose diet was so deficient. In his writings from Paris, he urged the planting of a tree for each slave born in the New World so that it could provide both oil and fruit. Unfortunately, his experiment never bore fruit, and while he was certain it was because his farm managers were just too unfamiliar with the crop, it may also have been the hot damp climate of the area. From 1787 until his death in 1826, imported olive oil became a staple in his own diet. His yearly food imports to Monticello included four to five gallons of “Oil of Aix” from Aix en Provence, France.¹⁵  While it would take many years for his dreams of lush olive groves providing quality olive oil at low cost to the public, when it was realized, it would be located in California, 3000 miles away from Jefferson’s home. Reflecting back on his life, he ranked his introduction of the olive tree and rice to the United States as equal to his writing of the Declaration of Independence.¹⁶ 

When did the first olive tree come into existence? When did domestication begin? When was the earliest olive oil production? Archeologists, archeobotanists, phyllogeographers (scientists who analyze gene diversity), and geneticists have all contributed to our understanding of the origins of modern olives and to the close relationship between human civilizations and olive cultivation.

Olea oleaster is a near ancestor to the olive tree with small oil bearing fruit that tends to adopt an evergreen bush like stature. As shown in Figure 1.5, fossilized branches of Olea oleaster have been found in Santorini Greece and dated back to the 50th Millennium BCE.

Carbon dating is a technique for determining the age of once living organic material by measuring the amount of radioactive isotope of carbon (¹⁴C) left in the sample. For archeological purposes, carbon dated results are often good enough to place the samples within historical context. The 5730 year half-life of ¹⁴C effectively limits its usefulness to dating objects that existed in the last 50 000 years. Carbon dating of charred wood fragments found next to an early human settlement indicated that by the 45th Millennium BCE our ancestors burned olive wood in their campfires.¹⁷  By the 10th Millennium BCE, early humans harvested wild olives and pressed them to collect the oil.

Controlling the genes of a plant or animal in order to get superior offspring has been a version of genetic modification since ancient times. This process, called cultivation, is at the foundation of human civilizations. The natural world propagates fruit trees from the fertilized seeds of the fruit that are dispersed randomly through the environment and germinate if they happen to fall upon fertile soil. In these cases, the DNA of the new tree has been created by sexual reproduction and is varied. By contrast, vegetative propagation or cultivation is essentially a cloning process by which a cutting is taken from a tree, and a new tree is grown from this cutting. Here, the DNA is identical to the mother tree. The variation in the genetic profile of fossilized or preserved ancient trees gives us a window into the cultivation of wild trees by ancient humans.

Much of the discussion about where olive cultivation first began focuses on the southern and northwestern ancient Levant territories, as shown in Figure 1.6. By the 8th Millennium BCE, there is evidence from phyllogeography that along the Turkish/Syrian border humans experimented with grafting high fruit bearing cuttings onto more robust but poor fruit bearing root stocks.¹⁸  Once early farmers encountered a superior fruit with more flesh and a higher oil content they would have taken cuttings of that tree and propagated orchards from this. It is thought that the spread of cultivated olive trees from the Near East occurred first throughout the Levant, including Cyprus, and then further into the western Mediterranean in two lineages, one via Libya towards Italy and the other through Morocco towards Iberia.

When cuttings of these trees reached their new homes, it would be likely that they would be further crossed with local wild varieties, leading to more confusion of cultivar identities. From this point forward, the practice of cultivating olive trees by grafting and pressing olives into oil spread from Asia Minor to the rest of the Mediterranean basin. Phoenician sailors brought first olive oil, and then olive tree cuttings and knowledge of best practices for cutting and pressing, to the westernmost Mediterranean basin, including France, Spain, and North Africa.

By the 7th Millennium BCE, the late Neolithic olive oil “industry” had developed to the point where the pressing was done regionally rather than individually, as evidenced from the thousands of crushed pits and pulp remains found in submerged prehistoric sites off the coast of Israel.¹⁹  The remains of jugs and jars containing olive oil dating back to the 6th and 5th Millennia BCE have been reported.²⁰  The oil is identified by analysis of the remnants by a process known as gas chromatography, which is explained in greater depth in Chapter 6. Analysis of one microliter of sample is enough to detect the length of carbon chains and their levels of unsaturation. High levels of oleic acid (18C chains, with one unsaturation) convinced the team to conclude the sample must be olive oil. In the 3rd and 4th Millennia BCE Minoan culture on the island of Crete had fully integrated olive oil into their daily lives, olive cultivation into their agricultural practices, and the reverence of olive trees into their spiritual lives, as can be found in paintings and artifacts. The great 6th Century philosopher, mathematician, and scholar, Thales of Miletus showed he could predict olive harvests in what is now modern day Turkey.²¹  Predicting a good harvest based on several observations of weather and rainfall, Thales reserved the regions presses in advance at a low cost, and then when the time came and the harvest was indeed plentiful, he sold back time on the presses to the farmers at a high rate. It is reported he did this not to make himself wealthy, but to prove the power of the scientific reasoning.

While excavating the ancient Ionian settlement of Klazomenai in the heart of the modern olive region near Izmir, Turkey, archeologists found three deep pits, cut a meter deep into the bedrock and connected by small channels. An additional channel led toward a couple of shallower square reservoirs carved into the rock. Some additional marks and indentations led the archeologists to believe that they were viewing an early industrial olive press dated to 600 BCE. Later, excavation of the site revealed an adjacent waste collection site for olive pits that clearly demonstrated the use of the facility as a regional olive press. Today the site, close to the modern day city of Urla, has been reconstructed as an educational museum with an active press. Figures 1.7 and 1.8 show how archeologists believe the press was operated 2500 years ago.

Turkish poet Nazim Hikmet wrote “you must take living so seriously that … even at seventy, you’ll plant olive trees.”²²  In the Mediterranean, long-lived olive trees are considered to be both a link to the past and one’s ancestors, and a link to the future and one’s descendants. For scholars, the olive tree’s incredibly long life span and the amount of influence it has had on the history, culture, and economy is a source of inspiration and amazement. Some go as far as claiming that the domestication of the olives (wheat and wine) is the reason for the emergence of Mediterranean civilization, which is considered to be the cradle of modern western civilizations.¹⁸  The questions are endless. How does the tree live so long? How does it remain fertile through millennia? Can it make those who consume its oil live long as well? Can the longevity of the olive tree give us any hints about extending our own life spans?

Thousand-year old trees – called millennial trees – exist today in places such as Sicily, Crete, Cyprus, and some remote areas of the Mediterranean. One of them is the monumental tree at Kavusi, Crete, shown in Figure 1.9, which is documented to be more than 3000 years old and is registered as a natural treasure. It sits in a secluded glen with a view of the sea. At nearly seven meters high and with a canopy of nearly 11 meters in diameter, the tree is massive, majestic, and stands in a small grove with sister trees of similar vintage. Grafting scars tell us that around 1000 BCE farmers on the island knew enough to take a hearty root stock and graft to it small branches from trees that produced abundant fruit. Today, the trunk, which is nearly five meters in diameter, is gnarled, pocked with bore holes that small boulders can fit into, and twisted by the winds and the weather. One cannot help but feel small and insignificant in its presence. The tree has witnessed so much human history: the lives of men long before the birth of Christ and long before colonization movements sent armies from Greece, or Rome, or the Ottomans, or Crusades, and more. And still it lives.

The grove is a 30-minute drive off a major highway up a twisty, rough-and-tumble country lane. For the hour we were there, we were the only visitors. All we could hear were the distant sounds of the wind in the trees and the occasional bells of sheep or goats on the hillside. In late December, the tree was heavy with Koroneiki fruit and stood awaiting harvest. To get oil from this tree felt a bit akin to making cider from apples harvested from the Tree of Knowledge. Yet, in its own humility, the giving tree at Kavusi has provided humans with oil from its fruit, light from its wood, and shade from its leaves for over three millennia. Its branches were even harvested and fashioned into a crown to honor the first female winner of the marathon at the 2004 Olympic games in Athens.

What happens to the olives from this tree once they are harvested? How will the oil be separated? What happens to make one oil better than another? To answer these questions, we begin by presenting a way of thinking about atoms and molecules that will make clear such simple things as why water and oil don’t mix. In later chapters, we will use this model to explain even much more complicated questions, such as why the olive fruit is making oil in the first place, what telltale signs allow the farmers to know that the fruit is ready for harvest, and why time is of the essence in getting the fruit to the olive press. It will allow us to go with the olive into the olive press and understand how the press separates the oil from the rest of the fruit and how, why, and when olive oil goes bad. A molecular understanding of the oil provides answers to all of these questions and more. Most importantly, the answers will help us appreciate the differences between one oil and the next and to know that the work of producing a high-quality extra virgin olive oil is no accident.

Molecules are almost unimaginably tiny. It would not be possible to see one using even the most powerful light microscope. By the time that we notice them, they will be present in almost unimaginably large numbers. The next time you measure out a tablespoon of olive oil, think about the fact that your spoon will hold more than a billion trillion molecules.

The atoms. The building block for all matter is the atom, and individual atoms connect with each other to form molecules. The identity and precise arrangement of atoms in a molecule determines the substance’s utility and properties. Early models used wooden balls and sticks to show the locations of atoms and the bonds that hold them together. If you’ve seen models of molecules in books or movies, you might recognize the general form of the ball and stick image in Figure 1.10. It is a model of one of the simplest molecules – water, H₂O – with two atoms of the element hydrogen (H) each shown as a small white ball and one atom of the element oxygen (O) shown as a larger red ball. Each atom provides a nucleus that has nearly all of the mass of the atom and also possesses a strong positive electrical charge due to the protons that reside there. For water, the nucleus of the heavier oxygen atom has eight protons and the lighter hydrogen nucleus has but a single proton.

The bonds. If a nucleus was all there was to an atom, two atoms would never come together to form a molecule, but would instead fly apart with tremendous force due to the repulsion of the positive charges of the two nuclei. Fortunately, the nuclei are held together by even tinier particles called electrons. Electrons have a negative electrical charge and so are naturally attracted to the positively charged nucleus of the atoms. Atoms in most of the molecules we will study here are neutral; that is they have an equal number of protons and electrons and so do not have a net charge. Some of the electrons stay close to the nucleus, tucked away from the outside world. The outermost electrons are called valence electrons, and they tend to spread themselves out over the molecule’s backbone, usually in pairs. Most of the electrons are found between the nuclei, and the attraction of two neighboring nuclei to the electrons is called a chemical bond. Sometimes, these valence electrons are pulled more toward one atom in a molecule, leaving that part of the molecule with an abundance of electrons and a partial negative charge while another part of the molecule with a shortage of electrons bears a partial positive charge. The water molecule is one such molecule in which the valence electrons are not evenly shared, and so the molecule ends up with an uneven distribution of charge. We say that such a molecule is polar. Because the ball and stick model by itself does not show us the charge distribution or polarity of the molecule, we wish to introduce another way of looking at molecules; that is by considering their “skin” or surface.

Figure 1.10 shows the balls (atoms) and sticks (bonds) standing like a skeleton inside the translucent surface of the molecule. Unless you are a chemist, you may never have seen the skin on the molecule before. This skin represents the outside of the whole molecule, not just the skeleton, and is formed from the outermost electrons. The valence electrons are constantly moving around the molecule at speeds close to the speed of light. The space occupied by a molecule depends mostly on the space explored by these exuberant electrons. While they don’t stay in one place for very long, they form a surface that defines the outside of the molecule. It’s a dizzying fact that everything we interact with in our daily lives is built this way. For water, you might also notice that the skin is not one color, but is slightly red on one side near the oxygen atom. Remember that the oxygen nucleus has eight protons so, with that much positive charge, it attracts the valence electrons very strongly, thereby creating a partial negative charge, which is shown in the surface model as slightly red near the oxygen. On the other side of the molecule that faces away from the oxygen and lies between the two hydrogen atoms, there is a corresponding blue color, indicating a partial positive charge. This surface model allows us to see that the water molecule is indeed polar and that the charge is not evenly distributed. The significance of this to a single molecule is small, but remember that molecules in our lives come in vast numbers. When two molecules approach each other, the negatively charged part of one is attracted to the positively charged part of the second, making them stick together more tightly. Many of the properties of water, such as its freezing point, boiling point, and density, will be derived from that fact. Whenever possible, we will represent molecules in this text with the skeletal ball and stick model within the skin so that you will be able to visualize the atoms and bonds as well as the true molecular size and shape and the distribution of charge in the molecule.

Of the many molecules in olive oil, triolein is the biggest contributor by weight and by numbers of molecules. It is part of a molecular family known as the triacylglycerides (abbreviated “TAGs”) and each member of the family has a very similar makeup. It is this molecule that is burned by your body to provide the important calories that you need to live – to have your heart beat, your lungs compress and expand, and your brain think. Though it has 224 atoms in one molecule, as food molecules go, it is mid-sized, which means that it is a bit bigger than a simple sugar but much smaller than complex carbohydrates (like starch) or proteins. The TAG molecules break down in your body to form fatty acids that are important sources of energy and building blocks that your body needs.

The atoms in triolein, as shown in Figure 1.11, are of three different elemental types: carbon – element number 6 with six protons shown in black; oxygen – element number 8 with eight protons in red; and hydrogen – element number 1 in white. The ball and stick model on the left shows that this complex molecule of 224 atoms is really made up of four different molecules stitched together: three long carbon chains called fatty acids and one short three carbon molecule, a glycerol, to which the three chains are all connected. The oxygen atoms connect the three chains to the bridge. In triolein, the three fatty acid chains that make up the bulk of the molecule are identical to each other and are named oleic acid in honor of the olive from which they are mostly derived. Each oleic acid has 18 carbon atoms and a strategically placed concentration of electrons right in the middle between carbons 9 and 10 that make a double bond. Notice the slight kink in the center of the chain that is caused by the double bond. In fact, olive oil has a fairly wide array of fatty acids in addition to oleic acid. Altogether, the fatty acids, including shorter ones (as few as 14 carbons) or longer ones (as many as 20 carbons) are used to use to make the TAGs.

The number of double bonds contained in each fatty acid is a very important property. A fatty acid with no double bonds is called a “saturated” fatty acid; if it has only one double bond, it is called a monounsaturated fatty acid (MUFA); and if it has more than one double bond, it is called a polyunsaturated fatty acid (PUFA). A number of properties and health effects depend on the mixture of saturated, MUFA, and PUFA molecules used to make the TAGs. The net result in olive oil is that triolein is present with a very large number of cousins, which all look very much like it but may have some subtle differences. These differences do not affect the flavor directly, and within the normal ranges of olive oil do not affect its utility. However, there can be a big difference in properties such as shelf life and smoke point. Healthy fats are described as those with less saturated fat, and we are all encouraged to shift our diets to one with less saturated and more MUFA and PUFA. Few oils have as much oleic acid as olive oil, making it an important part of our diet.

If we consider the surface of our triolein, as shown in the model on the right of Figure 1.11, we will notice that, unlike water, triolein is mostly green on the outside. This means that the valence electrons are evenly distributed and we say that the molecule is nonpolar. A small region of very slight positive and very slight negative charge exists on the lower left that is not significant. It may be important to note that the intensity of the color is related to the intensity of the charge imbalance. We said that in water molecules stick together positive end to negative end. Can the molecules of triolein stick to one another if the molecule is mostly neutral? Fortunately, the answer is yes! Weaker forces, called van der Waals forces, exist that make molecules stick together just because they would rather touch each other than be left with no neighbors. While these forces are individually much weaker than the polar forces that cause water molecules to stick together, there are many, many more of them to count when a molecule with 224 atoms approaches another molecule with 224 atoms. So, it can definitely stick together, and that is what we see with the oil.

Now, try to mix oil and water and what happens? As shown in Figure 1.12, the oil, because it is less dense, stays on the top of the bottle and the water sinks to the bottom. This fundamental property is a result of the charged surface of the water molecule finding no complementary charges in the oil molecule, and so it will prefer to stick to itself. In a similar way, the molecules of triolein prefer to be in the neutral environment provided by other triolein molecules, and so stick to themselves. If you have mixed a salad dressing with oil and vinegar (water) you have noticed that even if you shake it up to mix it, it will naturally separate. This fact – the separation of oil from water – is the foundation for almost all of the separation science that goes into making olive oil and its ability to dissolve other health giving compounds that are themselves not polar.