Английский язык. Профессиональное общение специалистов в сфере технологии продовольственных продуктов и потребительских товаров. Учебное пособие

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Choice of Dietary fat

Careful selection of diet in relation to nutrients is always important but probably more so in the dietary choice of fat. It must be in the light of major risk factors, such as hypercholesterolemia, hypertension, obesity, diabetes mellitus and, of course, excessive cigarette smoking. Over a wide range, serum cholesterol has been positively associated with coronary heart disease, so cholesterol levels in foods must be a major factor. Where the emphasis has been on animal (saturated) fatsand these include meat, animal fat, dairy products, also hydrogenated margarines and certain vegetable oil (coconut and palm oils) - these must be reduced and more polyunsaturated fats taken aiming at a radio of 2:1. In cases of obesity, the whole range of fats must be drastically reduced.

Eggs are a hazard owing to their high cholesterol; these should be severely restricted to not more than one or two a week, if not entirely omitted. The so-called «cream tea», beloved of social gatherings by women, and rich sugary/fatty confections should be avoided.

Loss of energy from fat restriction can be compensated by increasing compound carbohydrate foods, containing polyunsaturated fats and fiber. Switching from butter to margarine may be of no help if the latter is hydrogenated, i.e., all its carbon bonds taken up. Lowfat spreads, except for slightly reducing total fat intake, will convey no benefit unless the «margarine» component contains polyunsaturated fatty acids. The intake of these has significantly increased in the dietaries of many Western countries and in particular, it is possible that reduced incidence of coronary heart disease in the last decade may be a result of this. Mono-unsaturated fatty acids are prominent in the diets of some countries, such as olive oils, and the incidence of cardiovascular and other fat-orientated diseases has been consistently lower than Western countries in northern half.

The direct choice of dietary fats, i.e., between butter and polyunsaturated margarines, the restriction of dairy fats, eggs and meat, is no longer simple selection it once was. The rapid advances in food processing, including formulations has made it more difficult. Fatcontaining compound foods, many convenience foods, meat dishes, ready-to-serve meals, whole or in part, take-away meals - there is no knowledge of the type of fats they contain, and these foods form an increasing part of the national diet.

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2.Напишите краткое изложение (резюме) на русском языке понравившейся вам части текста.

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Text 2

1. Прочитайте текст 2 и скажите, какова роль жирных кислот Omega 3 и Omega 6 в жизни человека. В каких предложениях это наиболее точно сформулировано.

ALL ABOUT FATS AND FATTY ACIDS

Fats are a type of lipid involving three fatty acids hooked to a glycerol molecule making a fat molecule or a triglyceride. Triglycerides are also known as neutral fats and are the most common fats in the body serving as an energy source, as insulation, and as a protective cushion around organs. Saturated fats are usually solid at room temperature while unsaturated fats remain liquid.

Plants insert double bonds at different points in fatty acid chains than animals. Human beings, rarely if ever, insert double bonds into fatty acids with less than 16 carbon atoms in their chain. Human enzymes are not able to insert double bonds into positions closer than 7 carbons from the methyl end. Plants on the other hand insert double bonds as close as 3 and 6 carbons from the methyl end. This enables plants to produce 2 families of fatty acids known as the «Omega 3 and 6». These are two fats that are essential to human health but cannot be made within the human body and must come from an outside source.

Fat molecules are deposited in cells or transported to adipose tissue for storage. Killer saturated long chain fatty acids are sticky and the body cannot insert double bonds into these chains to make them unsaturated which could oxidize damaging arteries if the diet is lacking in antioxidants. Fatty acids from sugars interfere with fatty acid function increasing the likelihood of diseases from fatty degeneration. In addition, an excess of sugar consumption can also increase cholesterol levels in the blood.

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People on low fats diets generally lose 2-4 pounds during the first few weeks of a diet but then gain it back as the diet progresses. Having the right kind of fats (essential fatty acids) is what contributes to actual weight loss and stability. A survey taken in several European countries found that women who had the lowest fat intake were more likely to be obese but those with the highest fat intake were the least likely to be obese. There did not seem to be any relation between fat intake and obesity in men, however.

A fat substitute is the newest craze. One such is called Olestra by Proctor and Gamble. Olestra starts out as a 12 carbon molecule of sugar which is chemically processed so it can be attached to 6-8 fatty acids which surround and protect the sucrose center. In the mouth, it will trigger the same sensations as fat, but because it is a foreign substance, there will be no enzyme to process it. Therefore, it will slide through the digestive system intact - which most people think is advantageous. However, the problem is this. A fat substitute will affect the fat soluble vitamins and phytochemicals. These nutrients need a fat molecule to carry them into the bloodstream. Fat substitutes are unable to provide that vital service. Instead, they soak up these nutrients carrying them out into the faeces. Simplesse by Monsanto is another similar product as is Oatrim, which seems to have fewer negative effects than the other two.

All too often, fats are lumped together in «the bad» category. There are fats that are not only essential to good health but vital to weight stability. As far back as 1902, studies have been done showing that a high carbohydrate-low protein diet dispersed fat - as did a high carbohydrate-high protein diet. We now understand the reason for this. Fats are digested slowly over a 5-8 hour period resulting in a «full» feeling. Carbohydrates take 2-5 hours to digest resulting in hunger pangs striking much sooner leading to overeating. Essential fatty acids increase the metabolic rate helping to mobilize and burn excess saturated fats. The body then loses the craving for food when their needs for essential fatty acids (EFA) are satisfied. A poor diet greatly diminishes this control mechanism for hunger and people continue to eat thinking that they are really hungry when they are not.

The naming of fatty acids by scientists can be equated to the struggle any family goes through when faced with a new member

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joining its ranks. Sometimes a name is formed from the molecular structure and sometimes from where it was located when discovered. Proper names are governed by strict rules laid down by chemists and are decided upon by a committee. From there, these sometimes unwieldy proper names are reduced to nicknames more conducive to pronunciation. A few names derived from their origin of discovery are listed here just for interest sake.

Butyric acid named from butter. Caproic, caprylic, and capric acids (first found in goat's milk) from the Latin and astrological sign for goat - Capricorn. Oleic acid from olive oil. Linoleic and linolenic acids from the Latin word for flax - linum. Stearic acid from the Greek root word for fat - stea. Lauric acid from the laurel family of plants. Palmitic acid from the palm tree. Vaccenic acid found in cow's milk comes from the Latin word for cow - vacca.

Fats are the most concentrated source of energy the body has providing 9 calories per gram compared with 4 calories per gram of either protein or carbohydrates. They supply insulation for the body, protect vital organs with padding, and aid in the absorption and transportation of the fat soluble vitamins A, D, E, and K.

Without the proper amounts of essential fats, detrimental health disorders arise leading to autoimmune, inflammatory, and cardiovascular diseases. Those suffering from degenerative diseases such as obesity, cancers, cardiovascular disease, diabetes, and liver disorders usually have low levels of EFA in their tissues. These essential fats bring oxygen into the body and the lack of oxygen in the tissues is a key factor in degenerative disease. This type of oxygen is not the same as the destructive form caused by free radicals. EFA carry a slightly negative charge causing them to repel one another. This means they cannot aggregate (clump together) thereby keeping membranes fluid enabling them to carry toxins to the surface of the skin, intestinal tract, kidneys, or lungs where they can be discarded.

EFA are easily destroyed through cooking and processing, therefore, trying to obtain them solely from fish, for example, is not a reliable source. Most fish on the market today comes from «farms» which have much lower levels of EFA than those caught in the «wild». A more reliable source is cold-pressed Omega oils. Dairy products are also a very poor source of EFA with shellfish having the lowest content.

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Fats are comprised of glycerol, saturated fatty acids, monosaturated fatty acids, polyunsaturated fatty acids and essential fatty acids with each playing a different role in the body.

Glycerol can be manufactured by the body when supplies run low. The glucose molecule is split making two glycerol molecules when the body needs to make fats (triglycerides) out of excess sugars absorbed from the diet. Pharmaceutical preparations are called glycerin.

Saturated fatty acids form part of all membranes in the body but are used mainly as fuel. When there are too many calories in the diet from an excess of refined sugar, starches, etc, the excess must be taken out of the energy factory to prevent the Krebs cycle from «burning too hot». The body makes saturated fatty acids out of these excesses and stores them as body fat. In saturated fats, the carbons in the chain are completely «saturated» with all the hydrogen they can carry. Saturated fats form relatively straight chains that bunch closely together and the result is a dense, solid fat that does not melt at room temperature. Saturated fatty acids decrease the oxygen supply to body tissues (hypoxia) choking them by making the red blood cells stick together becoming less mobile and less able to transport oxygen, common in many degenerative diseases.

Saturated fats include: (The first number represents the number of carbon atoms in their chain and the second number represents the double bonds, if any, and a third number will indicate their position in the chain. See also under Unsaturated fats and Superunsaturated fats).

1.Butyric acid (4:0) is found in butter. Butyric acid helps feed the friendly bacteria and is the shortest saturated fatty acid. It also dissolves in water.

2.Caproic acid (6:0) is partially water soluble as is caproic acid.

3.Caprylic acid (8:0) inhibits the growth of yeasts and candidas in the intestinal tract by incorporating itself into the membranes of yeast cells causing them to rupture and die. Saturated fatty acids of longer than 8 carbons do not dissolve in water but readily dissolve in oil.

4.Capric acid (10:0).

5.Lauric acid (12:0).

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6.Myristic acid (14:0).

7.Palmitic acid (16:0) is found in large amounts in tropical fats such as coconut, palm, and palm kernel.

8.Stearic acid (18:0) is found in large amounts in beef, mutton, pork, butter, cocoa butter, and shea nut butter.

9.Arachidic acid (20:0) (NOT arachidonic acid) is found in

peanuts.

Monosaturated fats are used in the membranes similar to saturated fatty acids and can be broken down to produce energy in the same way by the same enzymes. When there is a deficiency of essential fatty acids, the monosaturated fatty acids try to make up for the loss but are not completely able to do so. A monosaturated fatty acid molecule has one double bond between the carbon atoms not saturated with hydrogen atoms. Monosaturated fats consist of:

1) w7's (palmitoleic acid - POA) is found in tropical oils. The body is able to convert POA into several other forms of w7's. People have constantly been warned of the dangers of palm and cocoanut oils because of the monounsaturated fatty acid called palmitoleic acid, yet, few even mentions that this acid is also found in milk;

2) w9's (oleic acid - OA) is found in large quantities in olives, almonds, avocados, peanuts, pecans, cashew, filberts, and macadamias and in the oils of canola, hazelnuts, and pistachios. Land animal fats and butter also contain some.

Foods rich in monosaturated fats are generally liquid at room temperature and semi-solid when refrigerated. Up to the mid 1980's, it was believed that monosaturated fats had a neutral effect on blood cholesterol levels. However, research since then has revealed that by replacing saturated fats with monosaturated fats can be more effective in lowering LDL («bad») cholesterol than by using polyunsaturated fats alone. However, an excess of monounsaturated fats can lead to health problems through the interference of the chemical conversions of essential fatty acids into prostaglandins.

Unsaturated fats consist of monounsaturated, polyunsaturated, and super unsaturated fatty acids. In unsaturated fats, the carbons carry less hydrogen making either mono or polyunsaturated. Because these chains do not have a full set of hydrogen atoms, the chain kinks and cannot bunch together resulting in them being more liquid at room temperature. The fewer the hydrogen atoms, the more kinks in

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the chain and the more fluid the fat. The following is a general rule of whether a fat will be fluid or solid:

a)up to 8 carbons is liquid at room temperature;

b)up to 10 carbons is liquid at body temperature;

c)more than 10 carbons is solid at body temperature.

The body metabolizes up to 12 carbon fatty acids to produce energy and are NOT stored as fat. For this reason they are incorporated into diets of those with digestive or liver problems and are also popular with athletes. However, too many medium chain fatty acids will produce an unpleasant scratchy sensation at the back of the throat. Therefore, only 1 or 2 tablespoons per day should be used for this purpose.

Superunsaturated fats are often referred to as «Omega 3» EFA which include:

1.Stearidonic acid [SDA] (18:4w3) is found in black current

seed oil.

2.Eicosapentaenoic acid [EPA] (20:5w3) is manufactured by the body to make series prostaglandins.

3.Docosahexaenoic acid [DHA] (22:6w3), and EPA are found in cold water fish and marine animals. Salmon, trout, mackerel, sardines and others are the riches sources of these fatty acids containing up to 30 % combined. Among the land animals, the brain, eyeballs, adrenal glands, and testes are the richest sources of these two fatty acids which explain why primitive tribes prized these organs and ate them raw immediately after a kill.

Polyunsaturated fatty acids are often referred to simply as «Omega 6» EFA and occur when a fatty acid has two or more double bonds between the carbon atoms. These include:

1.Linoleic acid [LA] (18:2w6) is found in safflower, sunflower, hemp, soybean, walnut, pumpkin, sesame, and flax oils. New genetic varieties of high oleic safflower and high oleic sunflower now contain only small quantities of LA whereas before they were the richest sources.

2.Gamma-linolenic acid [GLA] (18:3w6) is found in primrose, borage leaves, and spirulina but it can also be made by the body through conversion of alpha-linolenic acid (LNA). Gamma-linolenic acid is almost totally absent from mother's milk despite claims to the contrary. Human milk does contain DGLA (dibomogamma-linolenic

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acid) from which the body produces series 1 prostaglandins. Borage is the richest source at more than 20 %. Black currant oil contains about 15 % and evening primrose oil consists of 9 % GLA.

3.Arachidonic acid [AA] (20:4w6) is found in small amounts in animal fats and can be made in the body through the conversion of linolenic acid. It is not found in peanut oil despite claims.

Functions of Essential Fatty Acids:

1.EFA are the precursors for the production of prostaglandins which govern vitality, growth, mental state, and energy production.

2.EFA are necessary for oxygen transfer and have the ability to hold that oxygen in cell membranes acting as a barrier to viruses, bacteria, fungi, and other foreign invaders.

3.EFA speed healing by reducing inflammation in some immune dysfunctions such as arthritis.

4.EFA inhibit tumor growth.

5.EFA assist in hemoglobin production - vital to life.

6.EFA hold proteins, as well as oxygen, within cell membranes helping to create electrical currents for neurological transmission. Faulty transmissions result in nervous disorders.

7.EFA facilitate the conversion of lactic acid to water to carbon dioxide thereby speeding up muscular fatigue recovery.

8.EFA maintain stability in cell division by protecting chromosomes.

A deficiency of the proper fats will retard growth, and produce eczema/acne/dry skin/and dandruff, dry/dull/brittle/and sparse hair, soft/brittle/flaking nails, dry eyes and mouth, diarrhea, allergies, varicose veins, decreased or increased weight, gallstones, decreased radiation resistance, heart disease, cancers, deterioration of skin, sterility, swollen joints, liver deterioration, fatigue, emotional agitation, decreased immunity and etc. Too much of them will also produce an abnormal weight gain diminishing the metabolism.

Inhibitors of the essential fats are: saturated fats, saturated fatty acids, nonessential fatty acids, trans fatty acids, alcohol, diabetes, aging, cholesterol, heat, oil processing, oxygen ferrous sulfate, viral infections, radiation, cancer, and a decreased intake of vitamins C and zinc.

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benzene substance that irritates the digestive tract and causing water retention in the lungs producing, SOB (shortness of breath), and paralysis. This oil also contains high levels of pesticide residue. Refining is able to remove only some of these toxic substances.

Herring and capelin oils contain 10-20 % of cetoleic acid, which is toxic.

Menhaden and anchovetta oils contain a small amount of cetoleic acid.

Castor oil contains 80 % ricinoleic acid, known to be an intestinal purgative. Prolonged use can affect nutrient absorption.

Brominated oils are the result of adding bromine to the unsaturated fatty acid component of a vegetable oil. They are made from olive, corn, sesame, and cottonseed oils.

Brominated oils have been used for more than fifty years to enhance cloud stability in bottled drinks and to prevent ring formation around the necks of bottles. They are known to cause thyroid enlargement, fatty liver, kidney damage, changes in the heart tissue, and also withered testicles.

Refined peanut and avocado oils withstand heat well, but since they are refined, they add nothing nutritionally.

High oleic sunflower and safflower oils are stable but hard to find. The low oleic oils, called monosafflower or sunflower oil by traders, were created by genetic engineering, and are not suitable for high temperature cooking. Traditional Chinese cooks add a little water to the wok, lowering the temperature of the oil - a wise practice which is not held to by most western Chinese cooks. Frying should not be done because of the production of carcinogenic substances, but low temperature «stir-frying» for short periods is almost acceptable.

Exotic Oils: Kukui, or Candlenut tree, grows only in tropical climates of Hawaii and the Pacific Islands to New Zealand. It is the state tree of Hawaii. The nut oil is so rich that it burns, which is how it obtained its name, after western explorers saw the nuts being put on poles and used as torches. The shell was polished for necklaces. The oil was used for cosmetic purposes, keeping the skin soft and supple while protecting it from the sun. The nut flesh was used for medicinal purposes. The oil contains about 40 % LA (w6) and 29 % LNA (w3).