TABLE OF CONTENTS In addition to proteins, fats and carbohydrates, there are three other classes of compounds routinely found or used in foods that yield energy in the diet: polyols, organic acids, and ethanol. Although they do not usually contribute significant amounts in most foods, they are required by law to be included in the calculations of the total energy content of a food.
Polyol is a term used to describe a chemical with alcohol groups on several carbon atoms. The most widespread in nature is glycerol, which is usually esterified to fatty acids in triglycerides and phospholipids. Unless present in a food as free glycerol (i.e. not in combination with fatty acids), this would be covered in declarations of the fat content of the food (see above). Most of the other polyols occurring in foods are sugar alcohols: sorbitol, mannitol, xylitol, maltitol and lactitol, derived from the sugars glucose, mannose, xylose, maltose and lactose respectively. In addition, isomalt is a mixture of glucose-sorbitol and glucose-mannitol compounds (Smith, 1991). Sorbitol is found naturally in some fruits, and mannitol and xylitol are also naturally occurring, but most dietary intake of polyols occurs as a result of their use as sweetening agents and bulking agents. Although they are generally slightly less sweet than glucose and sucrose, they have low cariogenicity, their metabolism is insulin-independent and they do not cause a rise in blood glucose levels after consumption. Polyols are used in confectionery products as bulking agents, i.e. at levels...
