Carbohydrates
For such activities as breathing, the heartbeat, the maintenance of body temperature and others any person needs energy. We can get it from protein, fat, alcohol. But from carbohydrates we get most of the energy that we need. There are three major groups of carbohydrates in food: sugars, starches, cellulose and related materials. They all are compounds of carbon, hydrogen and oxygen and their chemical structures are based on a common unit (as a rule it is glucose). These units can be linked together in different ways and in different numbers. Classification of carbohydrates depends on the number of such units.
Sugars and starches are a major source of man’s food energy all over the world.
Glucose, fructose and galactose are monosaccharides (or simple sugars), and they are the units of more complex carbohydrates. Glucose occurs in fruit and plant juices and in the blood of living animals. During digestion most carbohydrates in food convert to glucose. From partial hydrolysis of starch we can get glucose syrups (or liquid glucose). Fructose occurs in some fruit and vegetables and especially in honey. It is the sweetest sugar that we know. Galactose does not occur in the free state, but it forms part of lactose.
Disaccharides consist of two monosaccharides linked together. They are sucrose, maltose, and lactose. Sucrose is a chemical combination of glucose and fructose. "Sugar" is a pure sucrose. Maltose is a combination of two glucose units. It is formed during the breakdown ' of starch by digestion. Lactose is a combination of glucose and galactose. It occurs only in milk.
5. Read the following text and translate it:
Sugars and Non-Sugar Sweeteners
The main sources of sugars in the diet are sugar, sweets and chocolates, milk (as lactose), fruit and fruit products, biscuits and cakes. All sugars dissolve in water and are differently sweet in taste. Sugars usually form white or colourless crystals when the water in which they are dissolved becomes supersaturated.
Sugars are sources of energy and sweetness. But also they are used in jam-making, canning and freezing as preservatives. In biscuits, cakes, soft drinks and some other foods they help to provide their characteristic texture.
Besides there are some other substances which also taste sweet. Sorbitol and mannitol, which are made from glucose or sucrose, are sometimes used in diabetic foods because they are absorbed slowly. However, their energy value is as large as that of glucose. In contrast, saccharin has no chemical or nutritional relationship to sugars and provides no energy.
Non-sugar sweeteners do not rank as foods, but they may be used as sweetening agents when it is necessary to make the amount of sugars in the diet smaller.
6. Translatethefollowingsentences:
1. Каждому человеку нужна энергия. 2. Из углеводов мы получаем большую часть необходимой энергии. 3. Есть 3 основные группы углеводов в пище: сахара, крахмалы, целлюлоза. 4. Сахара - источник энергии и сладости. 5. Сахар используют при приготовлении джемов как консервант. 6. Существуют другие вещества сладкие на вкус. 7. Заменители сахара не являются пищей. 8. Они делают количество сахара в еде меньше.
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Polysaccharides
1. Изучите представленные слова и словосочетания:
number ['nᴧmbә] n число; номер; anumberof некоторое количество
compose [kәm`pouz] v составлять; to be composed of состоятьиз
exist [ig'zist] v существовать
flour ['flauәj n муку; порошок
potato [pә`teitou] n картофель
eat [i:t] (ate, eaten) v есть
raw [ro:] а сырой; недоваренный
gelatinize [ʤi'lᴂtinaiz] v превращаться в студень
swell [swell] v раздуваться, увеличиваться
break ['breik] (broke, broken) v разбивать (ся), разрушать (ся)
root [ru:t] n корень
turnip ['tɜ: nip] n репа
stiff [stif] а тугой, негибкий
jelly['ʤeli] n желе; холодец
faeces [`fi:si:s] n осадок
although [o:1`ðоu] cj хотя; несмотря на то что
toothdecay– разрушение зубов
disease [di`zi:z] n болезнь
bowelcancer - раккишечника
intolerance [in'tolorans] n нетерпимость
2. Прочитайте текст. Найдите в нем предложения, содержащие Present Indefinite Active, переведите их.
Polysaccharides
There are a number of starches, which are polysaccharides. They are composed of large numbers of glucose units linked together, which form straight and branched chains (amylose and amylopectin). They exist in granules of a size and shape characteristic for each plant. In this form they are insoluble in water. And foods such as flour and potatoes are indigestible when eaten raw. When heated or cooked in the presence of water, the starch granules swell and gelatinize. They can be more easily digested.
Glycogen is similar to starch in composition, but is made from glucose only by animals, not by plants. There are small amounts of it in the liver and muscles as an energy reserve.
Cellulose provides the rigid structure of vegetables, fruits and cereals. It is insoluble in water. Cellulose consists of many thousands of glucose units. It cannot be digested by man, but can be used as food by cows, whose digestive tract has microorganisms able to break it down into glucose.
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Pectin is another complex polysaccharide present in apples and many other fruits and in such roots as turnips. Its property of forming a stiff jelly is important in jam-making. Pectin is completely digested and has little effect on the faeces, yet it is often considered as a part of dietary fibre.
3. Выпишите английские эквиваленты следующих словосочетаний:
Крахмал, соединения глюкозы, соединенные вместе, прямые и разветвленные цепи, существовать, размер, форма, растение, нерастворимый в воде, мука, неусвояемый, сырой, нагревать, схожий, состав, количество, обеспечивать, злаки, пищеварительный тракт, корнеплод, свойство, пищевая клетчатка.
4. Read the text and render it in Ukrainian:
Health Aspects of Carbohydrates
Fruits and vegetables form sugars in their leaves with the help of sunlight, and store them as starch. Although all sugars and starches absorbed by the body give similar amounts of energy, they have different physiological effects.
Starch provides the greatest part of man's food energy. Sugars are present in the diet as lactose from milk, and fructose from fruit and honey. But excessive consumption of sugars and sweets is associated with tooth decay, development of obesity, heart disease, and bowel diseases such asappendicitis and bowel cancer. At the same time, if diets are low in fat but it is necessary to maintain energy intakes, it is better to eat starchy foods than those of sugars, protein, and alcohol.
Some individuals, especially of non-white races, have a limited ability to digest lactose. Lactose intolerance is not usually found in infants whose diet depends on milk,but it may develop in later life.
Diabetes is the result of eating large amounts of readily absorbed carbohydrates. Although there are no recommendations for the amounts of sugars, starches or dietary fibre to be eaten by men, women or children, it is useful to know the amounts of these constituents in foods. The normal daily consumption of sugar should be 100 grams. The proportion of protein, fats and carbohydrates in the daily ration should be as follows: 14—15 % protein, 30 % fats and 55 % carbohydrates.
5. Answer the questions:
1. What are starches?
2. What units are starches composed of?
3. Are starches soluble in water?
4. When can starches be easily digested?
5. What is glycogen made from?
6. Where can glycogen be found?
7. What does cellulose provide?
8. Where is pectin present?
9. Why is pectin important in jam-making?
10. What polysaccharides do you know?
11. What form are sugars present in the diet?
12. What should the proportion of protein, fats and carbohydrates in the daily ration be?