ABSTRACT
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Foods are derived from plant material, carcasses of animals, and single-cell organisms. They are composed mainly of water, saccharides, proteins, lipids, and minerals (Table 1.1). These main components serve as nutrients by supplying the human body with the necessary building materials and source of energy, as well as elements and compounds indispensable for the metabolism. Some plant polysaccharides are only partly utilized for energy. However, as dietary fiber, they affect various processes in the gastrointestinal tract in different ways (Kritchevsky and Bonfield, 1995). Foods also contain a host of other constituents present in smaller quantities, especially nonprotein nitrogenous compounds, vitamins, colorants, flavor compounds, and functional additives. Many of the minor components originally present in foods are nutritionally essential, e.g., vitamins (some can be utilized by the body) and amino acids. Numerous groups, including tocopherols, ubiquinone, carotenoids, ascorbic acid, thiols, amines, and several other nonprotein
nitrogenous compounds, serve as endogenous muscle antioxidants, playing an essential role in postmortem changes in meat (Decker et al., 2000). Other minor components are useless or even harmful if present in excessive amounts. Most food raw materials are infected with different microorganisms — putrefactive and often pathogenic — and some contain parasites. A variety of compounds are added intentionally during processing to serve as preservatives, antioxidants, colorants, flavorings, sweeteners, and emulsifying agents and to fulfill different other technological purposes. The chemical nature and role of functional food additives are presented in detail in Chapter 12.
