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Carbohydrates II I hope that 7 days break from all the technical terms was enough in order to tackle the next lot, namely: DISACCHARIDES. On hydrolysis, disaccharides yield 2 monosaccharide molecules. Three particular disaccharides deserve mentioning: Sucrose, Maltose, Lactose. The disaccharide, sucrose, consists of one molecule of each of the two monosaccharides , glucose & fructose. Sucrose is found in fruits and vegetables and is particularly plentiful in beetroot and sugarcane. Refined white and brown sugar are close to 100 % sucrose. MALTOSE. This disaccharide, unlike sucrose, is not consumed in large amounts in the average Western diet. It is found in malted cereals, malted milks, and sprouted grains. Maltose occurs in the body as an intermediate product of starch digestion. LACTOSE. This disaccharide is found only in milk. Human milk contains about 4.8 g per 100 ml and cow's milk contains about 6.8 g per 100 ml. The enzyme LACTASE is needed to digest lactose and this enzyme is not present in most, if any, people over the age of 3. This is one of the many reasons why milk should not be consumed by humans over 3 years of age. POLYSACCHARIDES. Like the disaccharides, polysaccharides can not be directly utilized by the body. They must first be broken down into monosaccharides, the only sugar form that the body can use. There are 4 important polysaccharides, STARCH, DEXTRIN, GLYCOGEN, CELLULOSE. STARCH is abundant in the plant world and is found in granular form in the cells of plants. These starch granules are laid down in the storage organs of the plants. In the seeds, tubers, roots, stem and pith. They provide a reserve food supply for the plant, sustain the root or tuber through the winter and nourish the growing embryo during germination. DEXTRIN. There are several "varieties" of this polysaccharide. Dextrin are most commonly consumed in cooked starch foods, as they are obtained from starch by the action of heat. GLYCOGEN is the reserve carbohydrate in humans. It is to animals as starch is to plants. Glycogen is stored primarily in the liver and muscles of animals. About 2/3 of total body glycogen is stored in the muscles and about 1/3 is stored in the liver. CELLULOSE. Cellulose comprises over 50 % of the carbon in vegetation and is the structural constituent of the cell walls of plants. Cellulose is therefore the most abundant naturally-occurring organic substance. This polysaccharide can be digested only by herbivores such as cows, sheep, horses etc.. as these animals have bacteria in their rumens ( stomachs ) whose enzymes break down cellulose molecules. Humans do not have the enzymes needed to digest cellulose, so it is passed through the digestive tract unchanged. There is one basic role of carbohydrates in the human diet, to supply energy. It should always be kept in mind that carbohydrates or calories alone cannot adequately supply our energy needs, for we must have our carbohydrates in combination with other needs, such as proteins, water, vitamins, minerals, fats etc.. This means that a diet of refined sugars, refined flours, refined rice and other " food fragments " though it supplies calories, cannot satisfactorily comprise the bulk of anyone's diet. A person on such diet would suffer many problems, for the organism is not capable of living long or well on bare carbohydrates alone. They must be obtained in combination with the other essential food factors to be truly useful in the overall energy production and nutrition of the organism. How carbohydrates are digested will be the subject of next weeks lesson. Wishing you all a warm and cozy week The Crazy Nut team