Английский язык. Профессиональное общение специалистов в сфере технологии продовольственных продуктов и потребительских товаров. Учебное пособие
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Fats and oils are only sparingly soluble in alcohol but are readily soluble in ether, chloroform, etc. Fats and oils are insoluble in water. They have a greasy feel and produce characteristic transparent spots on paper.
All the naturally occurring fats and oils have a specific gravity of less than 1,0. The term specific gravity is used to denote the ratio between the weight of a substance and the weight of an equal volume of water. Usually the weights are compared at the same temperatures. Fats and oils are lighter than water and if they are poured into water they float on its surface.
A number of important functions of fat and oils are generally recognized. First, fat is the foodstuff which possesses the greatest caloric density of any of the foodstuffs. In the dry state, it yields 9,3 large calories per gram, as contrasted with values of 4,1 calories for protein and carbohydrate. Moreover fat is hydrophobic and usually occurs without water while both protein and carbohydrate are hydrophibic. Therefore, in nature the ratio of caloric value in foods between fat on the hand and protein and carbohydrate on the other hand is usually greater than 2.3:1. This ratio exists between these foodstuffs in the dry state.
Second, fat is a carrier of the fat-soluble vitamins. Not only does fat act as an excellent solvent for the carotenoids, vitamins A, vitamins D and the tocopherols, but it also protects them from oxidation to a much greater extent than if they were present in an aqueous suspension. Moreover, the presence of fats in the gastrointestinal tract with the fat-soluble vitamins may aid in the absorption of the latter. Phospholipids which occur to a greater or less extent in most natural fats furnish choline necessary for the synthesis of methionine.
The importance of dietary fat is not confined to the fat-soluble vitamins but its presence is also vital in some of the water-soluble vitamins. Besides fats are necessary in the diet to improve the palatability of the food. Low-fat diets prove to be very unappetizing; under conditions in which such a diet is required, it may bring about a voluntary reduction in food consumption.
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УПРАЖНЕНИЯ
10. Найдите в правой колонке русские эквиваленты следующих английских слов в левой колонке.
1) discovery |
а) рост |
2) certain |
б) растворитель |
3) growth |
в) открытие |
4) source |
г) сравнивать |
5) term |
д) определенный |
6) ester |
е) окисление |
7) solvent |
ж) состояние, условие |
8) to compare |
з) поглощение |
9) to protect |
и) термин |
10) oxidation |
к) источник |
11) condition |
л) эфир |
12) absorption |
м) защищать |
11. а) Найдите среди слов в правой колонке синонимы к словам в левой колонке.
1) to compose |
a) to produce, b) to compare, c) to consist, d) to use |
2) odor |
a) aid, b) flavour, c) diet, d) task |
3) greater |
a) lesser, b) latter, c) worker, d) more |
4) aqueous |
a) liquid, b) solid, c) acid, d) various |
5) to consume |
a) to confuse, b) to consist, c) to confine, d) to digest |
6) number |
a) amount, b) presence, c) failure, d) extent |
7) nutrition |
a) condition, b) absorption, c) nourishment, d) |
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recognition |
8) to exist |
a) to consider, b) to live, c) to occur, d) to reduce |
9) to possess |
a) to believe, b) to obtain, c) to have, d) to require |
10) foodstuffs |
a) absence, b) components, c) source, d) products |
б) Подберите к словам в левой колонке слова с противоположным значением из правой колонки.
1) recently |
a) lately, b) long ago, c) namely, d) after |
2) optional |
a) principal, b) special, c) compulsory, d) certain |
3) absence |
a) absorption, b) flow, c) property, d) presence |
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4) dry |
a) wet, b) wide, c) broad, d) light |
5) hydrophobic a) bright, b) hot, c) hydrophibic, d) clean |
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6) liquid |
a) flexible, b) pure, c) transparent, d) solid |
7) advantage |
a) ability, b) necessity, c) disadvantage, d) contrast |
8) soluble |
a) valuable, b) insoluble, c) aqueous, d) important |
9) different |
a) various, b) some, c) same, d) attractive |
10) saturated |
a) adequate, b) associated, c) essential, d) unsaturat- |
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ed |
12. Подберите к следующим терминам их определения. |
|
1) compound |
1. The process of supplying and receiving |
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nourishment. |
2) fat |
2. Liquid which does not mix with water, |
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obtained from animals, plants or found |
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in rock underground. |
3) flavour |
3. White or yellow substance, oily or greasy |
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which is purified for cooking purposes. |
4) liquid |
4. A distinctive taste, special quality |
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or characteristic. |
5) nutrition |
5. To make less, make smaller in size, number, |
|
degree. |
6) oil |
6. A substance like water or oil that flows |
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freely and is neither a solid nor a gas. |
7) to reduce |
7. A substance made up of two |
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or more combined parts. |
13. Вставьте следующие слова из рамки в предлагаемый ниже текст.
edible |
salad and table |
grades |
extraction |
value |
sediment |
constituents |
sardines |
lubricating |
quality |
Olive oil has been selected as typical of … oils. This is used in enormous quantities as a … oil, especially in the case of the bestflavoured and highest … . Large quantities of edible oil of a somewhat lower … are used for packing … and similar fish. Inferior
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grades are used as burning for … and in the textile industries and soap making.
Olive oil is prepared by expression or … from the fruit of the olive tree. The olives are gathered just before they are ripe since the oil of that time is of the highest quality. The … of olive oil as is true of the edible oils in general is largely dependent on its color, free from … and above all on the taste. Chemically, the principal … are glycerides of oleic and palmitic acids together with a smaller proportion of linoleic acid.
14. Употребите данные в скобках глаголы в соответствующей временной форме.
1.Olive oil (to be preferred) to other oils for salad dressing.
2.The importance of fats and oils (to be generally recognized) since the ancient time.
3.True fats and oils (to be composed) of hydrogen, carbon and oxygen.
4.The fat or oil (to be seldom distributed) evenly throughout the dough.
5.Technologists (to be given) new data about the sunflower oil last month.
6.Many nutritional problems (to be solved) by the scientists by the end of the 19th century.
7.Milk (to be consumed) in the form of cheese, butter and cream for many years.
8.The iodine value (to be defined) now.
9.They (to be helped) with this difficult problem next time.
10.Maize (to be introduced) into Spain by Arabs in the 13th century.
15. Повторите правило образования степеней сравнения прилагательных и наречий и переведите следующие предложения на русский язык.
1.Changes in fats can be detected by smell and taste before they can be detected by chemical tests, but in general the fresher the fat and the better its keeping quality, the better the keeping quality of the product it is combined with.
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2.Usually there is less fat absorption at higher cooking temperatures.
3.The larger the surface for a given weight of material, the greater the area over which fat may be absorbed.
4.It can be stated that the longer the food is cooked, the greater the fat absorption is.
5.The unsaturated fatty acids cover much greater areas per molecule than the saturated ones.
6.Shortening power or the ability of fats and oils to make a product tenderer so that it breaks or crushes more readily is due to several factors.
7.As a class the marine oils are among the cheapest of all fats and oils.
16. Найдите в тексте А предложения, в которых сказуемое выражено в форме страдательного залога. Переведите предложения.
17. Найдите в тексте А предложения с модальными глаголами. Переведите эти предложения.
18. Закончите предложения в соответствии с содержанием текста А.
1.Fat yields 9,3 large calories per gram as contrasted with values of 4,1 calories for …
a)protein and carbohydrate;
b)vitamins;
c)minerals.
2.The presence of fats in the gastrointestinal tract with the fatsoluble vitamins may aid in the absorption of …
a)glycerides;
b)fat-soluble vitamins;
c)fatty acids.
3.Fats and oils are insoluble in …
a)alcohol;
b)chloroform;
c)water.
4.Fats and oils are excellent solvents for …
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a)lipids;
b)aromatic compounds;
c)glycerol.
19.Ответьте на следующие вопросы.
1.What is the definition of fats and oils?
2.Is there any difference in general composition of fats and oils?
3.A good nutritional condition could be obtained in the absence of fat. Is it true?
4.What is the principal use of fats and oils in cookery?
5.What physical properties of fats and oils do you know?
6.What does the term specific gravity mean?
7.What are the functions of fats and oils?
20.Найдите в тексте А и прочитайте абзацы,
где говорится:
- об использовании жиров и масел в кулинарии; - о растворимости жиров и масел; - об удельном весе жиров и масел.
21.Составьте план пересказа текста А. Перескажите текст, пользуясь планом и выписанными ключевыми словами.
22. Прочитайте заголовок текста В и переведите его на русский язык. Просмотрите текст, обращая внимание на подчеркнутые предложения. Они помогут вам ответить на вопрос: «В чем состоит различие между жирами и маслами?»
Слова для понимания текста В.
keeping quality - устойчивость против порчи melting point - точка плавления
acid chains - кислотные цепи congealing point - точка затвердевания iodine number (value) - йодное число peroxide value - перекисное число hydrogenation - гидрогенизация
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Text B
The Distinction between Fats and Oils
The distinction between fats and oils is that at ordinary temperatures 18 to 24 C the fats are solid and the oils are liquid. Chemically the fats contain the higher percentages of the saturated glycerides than the oils, and the oils contain more the unsaturated glycerides than the fats. Of the three fatty acids, the components of fats and oils which combine with glycerol to form the molecule of fat or oil, all may be the same acid, or two of the acids may be the same and the third is different. Also each of the three may be a different acid. This gives many possible combinations of fats and oils. There are some main differences between fats and oils.
Melting point of fats. Because of the mixture of glycerides the melting points of fats are not constant but vary. The melting points of fats are not only affected by the percentage of their component unsaturated fatty acids but also by the length of the saturated acid chains. The shorter saturated fatty acids have lower melting points than the longer ones.
Congealing point. The solidifying point of a glyceride or a mixture of glycerides is lower than the melting point, the difference of the two being great. For example, a sample of butter melts at 34,5 but congeals at 22,7 C.
Iodine number (or value). The iodine value is defined as the number of grams of iodine absorbed by 100 of fat or other substance. The iodine is absorbed by the unsaturated carbons or at the double bonds. The class to which oil belongs is indicated by its iodine number. For example, lard, beef and mutton tallow have values below 100. The semidrying oils, which include oat, rice, rye, peach, cherry, and apricots kernels and many other have iodine value between 100 and 150.
Acid value. Acid value is defined as the number of milligrams of KON required to neutralize the free fatty acids.
Peroxide value. The peroxide value is the amount of peroxide which presents per 1000 grams of fat. It is expressed as milli - equivalent or as milli - moles (1 milli - mole equals 2 milli - equivalents).
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The peroxide value is determined in accelerated tests to learn the relative induction periods or relative keeping of fats.
Hydrogenation. Hydrogenation is the process by which hydrogen is added to the unsaturated carbon bonds of oils thus forming hard fats. By using a metal catalyst such as iron, copper, nickel or platinum at an elevated temperature in the presence of an atmosphere of hydrogen at their unsaturated bonds they become plastic, hard or brittle fats depending upon the completeness of hydrogenation.
Texture and consistency of fats. The texture or consistency of fat and hence its properties in baked products is not only influenced by its component glyceride but also by the rate of cooling and mechanical agitation. For example, if a sample of lard is cooled slowly, i.e. kept in a warm room at an incubator just below the congealing point of the fat, the glycerides with high melting points tend to crystallize and separate from those with low melting point. As a result the crystallized glycerides form granular spots surrounded by oil. If another portion of lard is chilled rapidly, there are fewer granules and the fat is not so granny.
Some free and uncombined fatty acids and glycerol are usually found ester fats. When heated to a high enough temperature the glycerol decomposes losing the molecules of water and forming acrolein. Acrolein is an aldehyde that has a sharp odour and is irritating to the nose, throat and eyes.
УПРАЖНЕНИЯ
23. Ответьте на следующие вопросы.
1.What is the distinction between fats and oils?
2.Why do the melting points of fats vary?
3.How is the iodine number defined?
4.How is the acid value defined?
5.What is the peroxide value determined in?
6.What process do we call hydrogenation?
7.What factors influence the texture of a fat?
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24. Найдите в тексте предложения, эквивалентные русским предложениям.
1.При температуре от 18 до 21 С жиры становятся твердыми, а масла - жидкими веществами.
2.Точка плавления жиров зависит от количества нерастворимых жирных кислот.
3.Вид масла определяется йодным числом.
4.Консистенция жиров в значительной степени зависит от глицеридного состава.
5.При нагревании до определенных температур глицероль распадается, теряя при этом молекулы воды. В результате образуется акролеин.
25. Укажите, какие предложения соответствуют содержанию текста В. Подтвердите свои ответы фактами из текста.
1.The melting points of fats are not affected by the percentage of their component unsaturated fatty acids.
2.Lipids include fats and lipoids (phosphatides, sterols and waxes).
3.The solidifying point of a glyceride or a mixture of glycerides is lower than the melting point, the difference of the two being great.
4.The most common saturated acids are palmitic and stearic fatty acids.
5.The class to which an oil belongs is indicated by its iodine number.
6.By using a metal catalyst at an elevated temperature in the presence of hydrogen they become plastic, hard or brittle fats depending upon the completeness of hydrogenation.
7.Most lipids are readily soluble in the so-called «fat solvents» such as benzene, petroleum and etc.
8.When heated to a high temperature the glycerol decomposes losing the molecules of water and forming acrolein.
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26. Выразите несогласие со следующими высказываниями и подтвердите свою точку зрения фактами из текста В. Используйте предлагаемые разговорные формулы.
It seems to be wrong; I can’t agree with you; as far as I know; that’s wrong; on the contrary.
1.Because of the mixture of glycerides the melting points of fats are constant.
2.The iodine value is defined as the number of grams of iodine absorbed by 1 gram of fat or other substance.
3.The peroxide value is the amount of peroxide which presents per 100 grams of fat.
4.Hydrogenation is the process by which oxygen is added to the unsaturated carbon bonds of oils thus forming hard fats.
5.The texture or consistency of fat and hence its properties in baked products is not influenced by the rate of cooling and mechanical agitation.
27. Прочитайте три отрывка. Озаглавьте каждый отрывок и скажите, дополняют ли они содержание текстов А и В или содержат новую информацию.
1. Shortening power has been defined and tested in various ways. The ordinary household way is to test the product by feel either by breaking or by crushing. That material has the greatest shortening power which when baked in dough under standard conditions gives to the product a maximum breaking strength. Shortening power or the ability of fats and oils to make a product tenderer so that it breaks or crushes more readily is due to several factors. These factors may be classified as follows: 1) differences in structure of the dough, 2) differences in absorption of different fats and oils at interfaces and orientation, and 3) the surface area covered by the fat or oil.
Differences in structure of butters and dough are due to several causes: the method of mixing or combining ingredients, the temperature of the ingredients when mixed, the extent of mixing, the plasticity of the fat used. The fat or oil is seldom distributed evenly through-