ABSTRACT
Understanding of nutrition at the molecular level began in the 19th century with the determination of the structures of the main food components, carbohydrates, fats, and proteins. The role of enzymes in the digestive process also began to be recognized. Urbanization and changed lifestyle patterns have resulted in the need for a complex system of food processing, storage, and distribution. This, along with changes in dietary preferences, has resulted in the use of many materials in food processing. These include natural gums and emulsifiers, chemically modified forms of cellulose, biologically modified substances such as high fructose corn syrup and xanthan gum, fat substitutes, low-calorie sweeteners, and preservatives. Food additives are subject to regulation by the FDA in the United States and most have been in use for many years. Other examples of chemically based food processing include coffee decaffeination, controlled fruit ripening, and fermentation process such as in the preparation of yogurt. The final quarter of the century saw increased incidence of obesity, type-2 diabetes and other conditions associated with the metabolic syndrome. Excess caloric intake and sedentary lifestyle appear to be the main causes, but specific food additives or contaminants have also been considered as possible contributing factors.
