Chapter 2: Sugars

Sugars are important components of a wide variety of human foods, especially those of plant origins. Explanations of the different chemical, physical and nutritional properties of different sugars and their solutions are often dependant on an in depth understanding of the various types of isomerism, notably optical, demonstrated by this class of carbohydrates. The behaviour of sucrose in food environments, particularly confectionery, and nutritional issues such as lactose intolerance and breakdown of vegetable oligosaccharides in the colon provide further illustrations of the structure/function interrelations of sugars. The thermal decomposition of sugars, in isolation in confectionery and caramel manufacture, and the Maillard reaction in the presence of proteins and amino acids is a source of both desirable flavour compounds and food colours as well undesirable compounds such as acrylamide and other potential carcinogens. Although most analytical procedures nowadays associated with food sugars depend on chromatography, enzyme based methods remain invaluable. (Enzymes are also widely used in the commercial manufacture of a variety of sugars from starch.) Traditional “wet chemistry” methods are still popular in teaching laboratories and at the opposite end of the scale stable isotope analysis enables discrimination between cane and beet sugar. For further study the chapter concludes with a list of specialist books and review articles.