Classification of fresh fruits and vegetables. Characteristics of individual species

07.09.2019 Salads

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Federal Agency for Education

GOU VPO "Samara State Economic University"

Service department

Course work

by discipline

Commodity researchand examination of food products

on the topic

2nd year students

Full-time education

Specialty "Service"

Yakovishenoy Evgeniya Valerievna

Samara 2008

Introduction

I.I.The chemical composition of vegetables and fruits

I.II Group characteristics of vegetables and fruits

II.I Benefits of vegetables and fruits

II.II Harm to vegetables and fruits

III.I Harm and benefits of watermelons

Conclusion

Applications

Used sources

Introduction

Relevance of the chosen topic

In the XX century, significant changes have taken place in human nutrition. Refined products began to predominate in the diet, the consumption of animal products increased sharply and the share of vegetables and fruits decreased. The added physical inactivity completed the picture: from overeating and inactivity, a person began to get sick heavily and often.

Vegetables are the most important suppliers of vitamins C, P, some B vitamins, provitamin A - carotene, mineral salts (especially potassium salts), a number of trace elements, carbohydrates - sugars, phytoncides that help destroy pathogenic microbes, and, finally, ballast substances. necessary for the normal functioning of the intestines.

A remarkable property of vegetables is their ability to significantly increase the secretion of digestive juices and enhance their enzymatic activity.

Meat and fish dishes are better absorbed by the body if they are consumed with vegetables. Vegetable dishes increase the secretion of the digestive glands and thus prepare the digestive tract for the digestion of protein and fatty foods. Therefore, it is useful to start lunch with vegetable snacks: vinaigrettes and salads, and then move on to soups, borscht, etc.

Vegetables are not only suppliers of important nutrients and vitamins, they are also dynamic regulators of digestion, increase the ability to assimilate nutrients, and, therefore, the nutritional value of most foods. Vegetables are very valuable and necessary for the body every day in all seasons.

In most regions of the Russian Federation, the consumption of vegetables and fruits fluctuates sharply and depends on the season. As a rule, there are enough of them in the second half of summer and autumn, and somewhat lacking in late winter and early spring. In addition, the nutritional value of vegetables and fruits of the previous year's harvest is significantly reduced in the spring months. The lack of nutrition of vegetables in winter and early spring is one of the reasons for the decrease in the overall resistance of the body to colds and infectious diseases.The daily intake of vegetables, except for potatoes, should be for an adult in all seasons from 300 to 400 grams. In no case should this amount be reduced during the winter and spring months.

The cultivation of early vegetables, the development of the suburban greenhouse economy, and the improvement of storage and canning methods ensure that they can be consumed all year round. The best way to preserve vegetables and fruits, the most perfect way to preserve their nutritional value and taste, is to freeze them. Quick-frozen fruits and tomatoes are very healthy. It is gratifying that recently more and more of them appear on the shelves of our stores. Unfortunately, we are still not using the huge variety of vegetables and fruits that nature gives us. Suffice it to say that of the many varieties of cabbage, white cabbage is the most common in our country. But it is not at all the most useful: cauliflower, Brussels sprouts, kohlrabi and other types of cabbage are much richer in vitamin C. In the spring period, a variety of vegetables are undeservedly little used in our diet: green onions, lettuce, spinach, rhubarb, etc. Green onions are especially useful at this time of year, 100 grams of which contains about 30 milligrams of vitamin C and 2 milligrams of carotene - provitamin A , which greatly helps to meet the daily requirement of an adult for vitamin C.

ChapterI

I. IThe chemical composition of vegetables and fruits

Vegetables are divided into:

tubers (potatoes, sweet potatoes),

root vegetables (radish, radish, rutabaga, carrots, beets, celery),

cabbage (white cabbage, red cabbage, Savoy, Brussels, cauliflower, kohlrabi),

onions (onions, leeks, wild garlic, garlic),

salad spinach (lettuce, spinach, sorrel),

pumpkin (pumpkin, zucchini, cucumber, squash, melon),

tomato (tomato, eggplant, pepper),

dessert (asparagus, rhubarb, artichoke),

spicy (basil, dill, parsley, tarragon, horseradish),

legumes (beans, peas, beans, lentils, soybeans).

Fruits are divided into stone fruits (apricots, cherries, dogwood, peaches, plums, cherries), pome fruits (quince, pears, mountain ash, apples), subtropical and tropical crops (pineapples, bananas, pomegranates, etc.), real berries (grapes, gooseberries , currants, barberries, lingonberries, blueberries, blueberries, cranberries, raspberries, blackberries, sea buckthorn) and false (strawberries).

Vegetables, fruits, berries and other edible plants have a high ability to stimulate appetite, stimulate the secretory function of the digestive glands, improve bile formation and bile division.

Plants rich in essential oils - tomatoes, cucumbers, radishes, onions, garlic, horseradish - are distinguished by their pronounced sokogonny effect. Of the pickled and pickled vegetables, cabbage has the most powerful appetite-stimulating properties, followed by cucumbers, beets, and least of all carrots.

Berries and fruits also have different effects on the secretory function of the stomach. Some (most) increase it (grapes, prunes, apples, strawberries), others (especially sweet varieties) - lower it (cherries, raspberries, apricots, etc.).

The sokogonic effect of vegetables, fruits and berries is explained by the presence of mineral salts, vitamins, organic acids, essential oils, and fiber in them. Vegetables activate the bile-forming function of the liver: some are weaker (beetroot, cabbage, swede juices), others are stronger (radish, turnip, carrot juice). When vegetables are combined with proteins or carbohydrates, less bile enters the duodenum than with purely protein or carbohydrate foods. And the combination of vegetables with oil increases the formation of bile and its entry into the duodenum, vegetables are stimulants of pancreatic secretion: undiluted vegetable juices inhibit secretion, and diluted ones stimulate it.

Water- an important factor that ensures the course of various processes in the body. It is an integral part of cells, tissues and body fluids and ensures the supply of nutrients and energy to tissues, excretion of metabolic products, heat exchange, etc. Without food, a person can live for more than a month, without water - only a few days.

Water is a part of plants in free and bound form. Organic acids, minerals, sugar are dissolved in freely circulating water (juice). Bound water entering plant tissues is released from them when their structure changes and is absorbed more slowly in the human body. Plant water is quickly excreted from the body, as plants are rich in potassium, which enhances urination. Waste products, various toxic substances are excreted in the urine.

Carbohydrates plants are divided into monosaccharides (glucose and fructose), disaccharides (sucrose and maltose) and polysaccharides (starch, cellulose, hemicellulose, pectin substances). Monosaccharides and disaccharides

dissolve in water and give the plants a sweet taste.

Glucose is part of sucrose, maltose, starch, cellulose. It is easily absorbed in the gastrointestinal tract, enters the bloodstream, and is absorbed by cells of various tissues and organs. When it is oxidized, ATP is formed - adenosine triphosphoric acid, which is used by the body for various physiological functions as a source of energy. With an excess intake of glucose into the body, it turns into fats. The richest in glucose are cherries, cherries, grapes, followed by raspberries, tangerines, plums, strawberries, carrots, pumpkin, watermelon, peaches, and apples. Fructose is also easily absorbed by the body and is converted to fats to a greater extent than glucose. In the intestine, it is absorbed more slowly than glucose, and does not need insulin for its assimilation, therefore it is better tolerated by patients with diabetes mellitus. Fructose is rich in grapes, apples, pears, cherries, cherries, then watermelon, black currants, raspberries, strawberries. The main source of sucrose is sugar. In the intestine, sucrose is broken down into glucose and fructose. Sucrose is found in beets, peaches, melons, plums, tangerines, carrots, pears, watermelons, apples, and strawberries.

Maltose is an intermediate product of the breakdown of starch; it is broken down into glucose in the intestine. Maltose is found in honey, beer, baked goods and confectionery.

Starch is the main source of carbohydrates. They are richest in flour, cereals, pasta and, to a lesser extent, potatoes.

Cellulose (fiber), hemicellulose and pectin substances are part of the cell walls.

Pectin substances are divided into pectin and protopectin. Pectin has a gelling property that is used in the manufacture of marmalade, marshmallows, pastilles, jams. Protopectin is an insoluble complexes of pectin with cellulose, hemicellulose, metal ions. The softening of fruits and vegetables during ripening and after heat treatment is due to the release of free pectin.

Pectin substances adsorb metabolic products, various microbes, salts of heavy metals that enter the intestines, and therefore foods rich in them are recommended in the diet of workers in contact with lead, mercury, arsenic and other heavy metals.

The cell membranes are not absorbed in the gastrointestinal tract and are called ballast substances. They participate in the formation of feces, improve the motor and secretory activity of the intestines, normalize the motor function of the biliary tract and stimulate the processes of bile secretion, increase the excretion of cholesterol through the intestines and reduce its content in the body. Fiber-rich foods are recommended to be included in the diet of the elderly, with constipation, atherosclerosis, but limited in case of gastric ulcer and duodenal ulcer, enterocolitis.

There are many cell membranes in rye flour, beans, green peas, millet, dried fruits, buckwheat, carrots, parsley, and beets. In apples, oatmeal, white cabbage, onions, pumpkin, lettuce, potatoes, they are somewhat less.

Dried apples, raspberries, strawberries, nuts, dried apricots, apricots, mountain ash, dates are the richest in fiber; less - figs, mushrooms, oatmeal, buckwheat, pearl barley, carrots, beets, white cabbage.

Most of the pectin substances are found in beets, black currants, plums, then in apricots, strawberries, pears, apples, cranberries, gooseberries, peaches, carrots, white cabbage, raspberries, cherries, eggplants, oranges, pumpkin.

Organic acids. Plants most often contain malic and citric acids, less often oxalic, tartaric, benzoic, etc. There is a lot of malic acid in apples, citric acid in citrus fruits, tartaric acid in grapes, oxalic acid in sorrel, rhubarb, figs , benzoic - in lingonberries, cranberries.

Organic acids enhance the secretory function of the pancreas, improve intestinal motor activity, and promote urine alkalinization.

Oxalic acid, combining with calcium in the intestine, disrupts the processes of its absorption. Therefore, foods containing large amounts of it are not recommended. Oxalic acid is removed from the body by apples, pears, quince, dogwood, decoctions of black currant leaves, grapes. Benzoic acid has bactericidal properties.

Tannins(tannin) are found in many plants. They give plants an astringent, tart taste. There are especially many of them in quince, blueberry, bird cherry, dogwood, mountain ash.

Tannins bind the proteins of tissue cells and have a local astringent effect, slow down the motor activity of the intestines, help normalize stool in case of diarrhea, and have a local anti-inflammatory effect. The astringent effect of tannins decreases sharply after eating, as tannin combines with food protein. In frozen berries, the amount of tannins is also reduced.

The richest in essential oils are citrus fruits, onions, garlic, radishes, radishes, dill, parsley, celery. They enhance the secretion of digestive juices, in small amounts they have a diuretic effect, in large amounts they irritate the urinary tract, but locally they have an irritating anti-inflammatory and disinfectant effect. Plants rich in essential oils are excluded for gastric ulcer and duodenal ulcer, enteritis, colitis, hepatitis, cholecystitis, nephritis.

Protein Soybeans, beans, peas, and lentils are the richest in protein from plant foods. The protein of these plants contains essential amino acids. Other plants cannot serve as a source of protein.

Vegetable protein is less valuable than animal protein and is less well absorbed in the gastrointestinal tract. It serves as a substitute for animal protein when the latter needs to be limited, such as in kidney disease.

Phytosterols belong to the "unsaponifiable part" of oils and are divided into sitosterol, sigmasterol, ergosterol, etc. They are involved in cholesterol metabolism. Ergosterol is a provitamin D used to treat rickets. It is found in ergot, brewer's and baker's yeast. Sitosterol and sigmasterol are found in grains, beans, soybeans, dandelion, coltsfoot.

Phytoncides are plant substances that have a bactericidal effect and promote wound healing. They are found in more than 85% of higher plants. The richest in them are oranges, tangerines, lemons, onions, garlic, radish, horseradish, red peppers, tomatoes, carrots, sugar beets, Antonov apples, dogwood, cranberries, bird cherry, lingonberry, viburnum. Some phytoncides retain their stability during long-term storage of plants, high and low temperatures, exposure to gastric juice, saliva. The consumption of vegetables, fruits and other plants rich in phytonutics helps to detoxify the oral cavity and gastrointestinal tract from microbes. The bactericidal property of plants is widely used for catarrh of the upper respiratory tract, inflammatory diseases of the oral cavity, for the prevention of influenza and the treatment of many other diseases. For example, garlic preparations are recommended for dysentery, orange and tomato juices - for infected wounds and chronic ulcers, lemon juice - for eye inflammation, etc. Phytoncides purify the air.

Vitamins- These are low molecular weight organic compounds with high biological activity, which are not synthesized in the body.

Plants are the main source of vitamin C, carotene, vitamin P. Some plants contain folic acid, inositol, vitamin K. There are few vitamins B1, B2, B6, PP and others in plants.

Vitamin C(ascorbic acid) stimulates oxidative processes in the body, activates various enzymes, participates in the normalization of carbohydrate metabolism, improves the absorption of glucose in the intestine and the deposition of carbohydrates in the liver and muscles, increases the antitoxic function of the liver, inhibits the development of atherosclerosis, increases the excretion of cholesterol through the intestines and lowers it level in the blood, normalizes the functional state of the gonads, adrenal glands, participates in hematopoiesis. The body's daily requirement for vitamin C is about 100 mg.

The main sources of vitamin C are vegetables, fruits and other plants. Most of it is in the leaves, less in fruits and stems. The peel of the fruit contains more vitamin C than the pulp. Vitamin C reserves in the body are very limited, so plant foods should be consumed throughout the year.

Vitamin C is rich in rose hips, green walnuts, black currants, red bell peppers, horseradish, parsley, dill, Brussels sprouts, cauliflower, green onions, sorrel, strawberries, spinach, gooseberries, dogwood, red tomatoes, wild garlic, oranges, lemons , raspberries, apples, cabbage, salad.

Vitamin P reduces capillary permeability, participates in the redox processes of the body, improves absorption and promotes the fixation of vitamin C in organs and tissues. Vitamin P exerts its effect only in the presence of vitamin C. The human requirement for vitamin P is 25-50 mg. It is found in the same foods as vitamin C.

Carotene in the animal body it is a source of vitamin A. Carotene is absorbed in the body in the presence of fat, bile and the enzyme lipase. In the liver, carotene, with the participation of the carotenase enzyme, is converted into vitamin A.

Carotene is found in green parts of plants, in vegetables and fruits of red, orange and yellow colors. Its main sources are red peppers, carrots, sorrel, parsley, rose hips, green onions, sea buckthorn, red tomatoes, and apricots.

With a deficiency of vitamin A, the body develops dry skin and mucous membranes, night blindness, the acuity of perception of color, especially blue and yellow, slows down the growth of bones and the development of teeth, decreases the body's resistance to infections, etc. The daily requirement of the body for vitamin A is 1.5 mg (4.5 mg carotene).

Vitamin K enters the body with animal and plant food, partially synthesized in the large intestine.

With vitamin K deficiency, symptoms of increased bleeding occur, the rate of blood coagulation slows down, and capillary permeability increases. The daily human need for vitamin K is 15 mg. Its main source is the green part of plants. Vitamin K is richest in spinach, white cabbage and cauliflower, nettle.

Folic acid synthesized in the intestine in an amount sufficient for the body. She participates in hematopoiesis, stimulates protein synthesis. The body's need for this vitamin is 0.2-0.3 mg per day. The richest in folic acid are spinach, watermelons, then melons, green peas, carrots, potatoes, cauliflower, and asparagus.

Inositol found in all plants and animal products. It is synthesized by intestinal bacteria and participates in the metabolism of proteins, carbohydrates, is part of various enzymes, and normalizes the motor activity of the stomach and intestines. The daily requirement for inositol is 1.5 g per day. Melon, oranges, raisins, peas, cabbage are the richest of plant products in inositol.

Vitamin B1(thiamine) normalizes the activity of the nervous system, participates in the metabolism of carbohydrates, proteins, fats, regulates the activity of the cardiovascular system, digestive organs. When it is insufficient, the products of incomplete metabolism of carbohydrates accumulate in the tissues, and the body's resistance to infections decreases.

Human need for vitamin B1 is 1, 5-2, 3 mg per day. Of the plant products, soybeans, peas, buckwheat, and bran are the richest in them.

Vitamin B2(riboflavin) normalizes the metabolism of proteins, fats, carbohydrates, regulates the functions of the central nervous system, liver, stimulates hematopoiesis, normalizes vision. The daily requirement for vitamin B2 is 2.0-3.0 mg per day. Its main sources are animal products. Soy, lentils, beans, green peas, spinach, asparagus, and Brussels sprouts are rich in this vitamin from plant foods.

Vitamin B6(pyridoxine) is involved in the metabolism of proteins, fats, and hematopoiesis. With its insufficiency, the activity of the central nervous system is disrupted, skin lesions, chronic diseases of the gastrointestinal tract occur. Pyridoxine is synthesized in the intestines. The body's daily need for it is 1.5-3.0 mg. Of the plant foods, the richest in vitamin B6 are beans, soybeans, buckwheat, wheat flour, wallpaper, potatoes.

Vitamin PP(nicotinic acid) normalizes the metabolism of carbohydrates, cholesterol, the state of the central nervous system, blood pressure, increases the secretory function of the glands of the stomach and pancreas. The daily requirement for vitamin PP is 15-25 mg. Legumes, barley, white cabbage, cauliflower, apricots, bananas, melons, eggplants are rich in vitamin PP from plant products.

Minerals are part of vegetables, fruits and other plants. Their composition in the same plants varies depending on the type of soil used fertilizers and the type of product. Plant foods are rich in calcium, phosphorus, magnesium, iron salts, are the main source of potassium salts, contain manganese, copper, zinc, cobalt and other trace elements, and are poor in sodium salts.

Mineral substances are part of cells, tissues, interstitial fluid, bone tissue, blood, enzymes, hormones, provide osmotic pressure, acid-base balance, solubility of protein substances and other biochemical and physiological processes of the body.

Potassium easily absorbed in the small intestine. Potassium salts increase the excretion of sodium and cause a shift in the urine reaction towards the alkaline side. Potassium ions support the tone and automatism of the heart muscle, the function of the adrenal glands. A diet rich in potassium is recommended for fluid retention in the body, hypertension, heart disease with arrhythmias, and in the treatment of prednisone and other glucocorticoid hormones.

The body's daily need for potassium is 2--3 g. Potassium salts are rich in all plant products, but especially dry fruits, berries (raisins, dried apricots, dates, prunes, apricots), then potatoes, parsley, spinach, cabbage, black currants , beans, peas, celery roots, radishes, turnips, dogwood, peaches, figs, apricots, bananas.

Calcium increases the excitability of nervous tissue, activates and normalizes the processes of excitation and inhibition in the cerebral cortex, enhances blood coagulation processes, regulates the permeability of capillary membranes, participates in the formation of teeth and bones.

Calcium enters the body with food. Calcium absorption is improved in the presence of phosphorus and magnesium ions and is impaired by fatty acids and oxalic acid. The human need for calcium is 0.8-1.5 g per day. Its main source among plant products is parsley (especially greens), apricots, dried apricots, horseradish, raisins, prunes, green onions, lettuce, cabbage, dates, dogwood, peas, parsnips.

Phosphorus is mainly found in the bone substance in the form of phosphorus-calcium compounds. Ionized phosphorus and organic phosphorus compounds are part of cells and intercellular fluids of the body. Its compounds are involved in the absorption of food in the intestines and in all types of metabolism, maintain acid-base balance. Phosphorus compounds are excreted in the urine and feces. The body's daily requirement for phosphorus is 1.5 g. The richest in them are carrots, beets, lettuce, cauliflower, apricots, and peaches.

Magnesium enhances the processes of inhibition in the cerebral cortex, has a vasodilating effect, participates in the metabolism of proteins and carbohydrates. With an excess of magnesium, the excretion of calcium from the body increases, which leads to a violation of the structure of bones. The body's daily requirement for magnesium is 0.3-0.5 g.

Magnesium is richest in bran, buckwheat and oatmeal, legumes, walnuts, almonds, as well as apricots, dried apricots, dates, parsley, sorrel, spinach, raisins, bananas.

Iron participates in many biological processes of the body, is part of hemoglobin. With its deficiency, anemia develops.

The human need for iron is 15 mg per day. The richest in them are apricots, dried apricots, apples, pears, peaches, parsley, somewhat less of it in dogwood, dates, peaches, quince, raisins, olives, prunes, horseradish, spinach. The iron of vegetables and fruits is absorbed better than the iron of inorganic drugs, due to the presence of ascorbic acid in plant products.

Manganese actively participates in the metabolism, in the redox processes of the body, enhances protein metabolism, prevents the development of fatty liver infiltration, is a part of enzymatic systems, affects the processes of hematopoiesis, increases the hypoglycemic effect of insulin. Manganese is closely related to the metabolism of vitamins C, B1, B6, E.

The body's daily requirement for manganese is 5 mg. They are the richest in legumes, leafy vegetables, especially lettuce, as well as apples and plums.

Copper participates in the processes of tissue respiration, the synthesis of hemoglobin, promotes the growth of the body, enhances the hypoglycemic effect of insulin, enhances the processes of glucose oxidation.

The body's daily requirement for copper is 2 mg. There is a lot of copper in legumes, leafy vegetables, fruits and berries, less in eggplants, zucchini, parsley, beets, apples, potatoes, pears, black currants, watermelons, horseradish, and pepper.

Zinc is part of insulin and lengthens its hypoglycemic effect, enhances the action of sex hormones, some pituitary hormones, participates in hemoglobin formation, affects the redox processes of the body. The human need for zinc is 10-15 mg per day.

Of plant foods, beans, peas, wheat, corn, oat flour are rich in zinc; in smaller quantities, it is found in white cabbage, potatoes, carrots, cucumbers, and beets.

Cobalt is a part of vitamin B. Together with iron and copper, it participates in the processes of maturation of erythrocytes. The body's daily requirement for cobalt is 0.2 mg.

Peas, lentils, beans, white cabbage, carrots, beets, tomatoes, grapes, black currants, lemons, gooseberries, cranberries, strawberries, strawberries, cherries, onions, spinach, lettuce, radishes, cucumbers are rich in cobalt.

I. IIGroup characteristics of vegetables and fruits

Given the wide variety of vegetables and fruits, let's get acquainted with their classification.

Vegetables are divided into:

Tubers (potatoes, sweet potatoes),

Root vegetables (radish, radish, rutabagas, carrots, beets, celery),

Cabbage (white cabbage, red cabbage, Savoy, Brussels, cauliflower, kohlrabi),

Onions (onions, leeks, wild garlic, garlic),

Salad spinach (lettuce, spinach, sorrel),

Pumpkin (pumpkin, zucchini, cucumber, squash, melon),

Tomato (tomato, eggplant, pepper),

Dessert (asparagus, rhubarb, artichoke),

Spicy (basil, dill, parsley, tarragon, horseradish),

Legumes (beans, peas, beans, lentils, soybeans).

The fruits are divided into:

Stone fruits (apricots, cherries, dogwoods, peaches, plums, cherries),

Pome fruits (quince, pears, mountain ash, apples),

Subtropical and tropical crops (pineapples, bananas, pomegranates, etc.),

Real berries (grapes, gooseberries, currants, barberries, lingonberries, blueberries, blueberries, cranberries, raspberries, blackberries, sea buckthorn)

False (strawberries).

ChapterII

II. IThe benefits of vegetables and fruits

Vegetables are of great importance in human nutrition. To eat right means to correctly combine plant and animal food in accordance with age, nature of work, state of health. When we eat meat, fats, eggs, bread, cheese, acidic inorganic compounds are formed in the body. To neutralize them, you need basic, or alkaline, salts, which are rich in vegetables and potatoes. Green vegetables contain the largest amount of acid-neutralizing compounds.

The consumption of vegetables helps to prevent many serious diseases, increases the tone and performance of a person. In many countries of the world in the treatment of various diseases with dietary nutrition, fresh vegetables occupy a leading place. They are rich in ascorbic acid (vitamin C), which ensures the normal metabolism of carbohydrates and contributes to the elimination of toxic substances from the body, resistance to many diseases, and reduction of fatigue. Many vegetables contain B vitamins that affect human performance. Vitamins A, E, K, PP (nicotinic acid) are present in green peas, cauliflower and green vegetables. Cabbage contains vitamin and, which prevents the development of duodenal ulcer.

Organic acids, essential oils and enzymes of vegetables improve the assimilation of proteins and fats, enhance the secretion of juices, and promote digestion. The composition of onions, garlic, horseradish, radish contains phytoncides that have bactericidal properties (destroy pathogens). Tomatoes, peppers, parsley are rich in phytoncides. Almost all vegetables are suppliers of ballast substances - fiber and pectin, which improve the functioning of the intestines, helping to eliminate excess cholesterol and harmful digestive products from the body. Some vegetables, such as cucumber, have low nutritional value, but due to the content of proteolytic enzymes in them, they have a positive effect on metabolism when consumed. Green vegetables are of particular value. Fresh, they are not only better and more fully assimilated by humans, but also help (with enzymes) the digestion of meat and fish in the body. At the same time, being cooked, green ones lose a significant part of their beneficial properties.

To meet the need for vitamins, carbohydrates, proteins, acids, and salts, an adult needs to consume more than 700 g (37%) of animal food and more than 1200 g (63%) of vegetable food, including 400 g of vegetables, daily. The annual demand for vegetables per person varies depending on the region of the country and is 126-146 kg, including cabbage of various types 35-55 kg, tomatoes 25-32, cucumbers 10-13, carrots 6-10, beets 5-10, onions 6-10, eggplants 2-5, sweet peppers 1-3, green peas 5-8, melons 20-30, other vegetables 3-7.

Vegetables increase the absorption of proteins, fats, and minerals. Added to protein foods and cereals, they enhance the secretory effect of the latter, and when used together with fat, they remove its inhibitory effect on gastric secretion. It is important to note that undiluted juices of vegetables and fruits reduce the secretory function of the stomach, while diluted juices increase it.

II. IIHarm to vegetables and fruits

Many people understand that the attractive appearance of any fruit and the absence of obvious signs of rot or immaturity does not mean its suitability for food. Too many factors influence it on the long journey of turning the seed into a dish on our table. What is at least an unfavorable ecological situation in which nine-tenths of domestic greens are grown. Soil soaked through with harmful mixtures; air saturated with toxic exhaust from cars and industrial pipes; water polluted by industrial emissions - all this, of course, does not add useful properties to vegetables and fruits.

In the process of cultivation, collection, pre-sale preparation and actual sale, each fruit passes through dozens of hands, which are far from always clean and healthy. But some infections may well "settle in the belly" of a tomato or apple, in order to subsequently move into your body. But that's not all. A huge problem is presented by all kinds of additives and preservatives with which fruits and vegetables are stuffed. Abundant processing of orchards and agricultural fields with various pesticides in an attempt to preserve and increase the harvest cannot but affect the content of harmful substances in the products. It makes no sense to talk about imported products at all, since the fruit cannot naturally preserve freshness and beauty, despite prolonged storage and long transportation. But domestic entrepreneurs do not hesitate to use "chemistry" in order to give an attractive appearance to their agricultural products. And everything would be fine if proper control over the quality and conformity of such additives was carried out. But many not very clean businessmen do not bother themselves with such "trifles". And the layman cannot carry out an independent check.

Russia ranks second in the use of chemicals in agriculture. And the last - according to their detection in food products grown in fertilized fields. The word "pesticides" literally translates from Latin as "I kill the infection." At one time, this drug became a salvation for agriculture. Later - a misfortune. Humanity faced the question: in connection with the progress of fresh fruits and vegetables - benefit or harm to the body? Today, many US universities have decided to teach only traditional farming. And, nevertheless, in America agricultural products are tested for 100 pesticides, in Europe - for 57. For comparison, in our markets, tests for pesticides are not carried out at all. Fruits and vegetables are tested for 4 pesticides only in one central laboratory in Moscow. And then, if suspicions arise. But, according to experts, such inattention to the problem is explained not by lack of money, but by the lack of it. We do not actively use pesticides just because they are expensive in our country. In any case, they can be washed off with water; you just need to wash the fruit well. It is more difficult with nitrates, which are introduced into the soil. The permissible level of nitrates per 1 kilogram of greenhouse cucumbers is 400 milligrams, and the permissible dose for an adult is 300 milligrams, for a child and an elderly person it is even less. Therefore, it is better not to rush to vitaminize your body with early fruits, the most dangerous of which is watermelon. To ensure the redness, sellers inject a syringe of vodka into the stalk. Only the inventors themselves never eat their "drunken" know-how. In addition, the largest berry in the world works like a huge sponge and absorbs harmful substances from water and soil, including nitrates. But regardless of the environmental situation or the presence of nitrates in fruits, vegetables and fruits in excessive quantities are harmful in themselves. For example, apricots, especially fresh ones, should not be eaten on an empty stomach, as well as after ingestion of indigestible food (mushrooms, beans, peas). Drinking cold water after taking apricots causes diarrhea. Fresh apricots are harmful to patients with peptic ulcer and acute gastritis. Due to the high sugar content, apricots, especially in dried form (dried apricots, apricots), are prohibited for patients with diabetes mellitus. The side effects of apricots on the digestive tract can be prevented or eliminated with dill water, fresh dill or anise. Many people like to eat apricot kernels. It is important to remember that they can cause severe poisoning. After 0.5-5 hours, you may feel general weakness, sore throat, headache, nausea, vomiting, and a feeling of fear. In severe cases, convulsions and loss of consciousness are noted. One of the symptoms of poisoning is the staining of the mucous membranes of the mouth in a scarlet color. When breathing, the smell of bitter almonds is sometimes felt. Home treatment may include gastric lavage, cleansing enemas. When using apricot seeds in small doses, poisoning does not occur.

Orange juice is contraindicated in the period of exacerbation of gastric ulcer and duodenal ulcer, in diseases of the pancreas and small intestine.

Watermelon has the ability to accumulate chemicals (saltpeter, etc.) used as fertilizer in fruits and roots. After cutting such a watermelon, yellow, somewhat compacted areas ranging from 0.3-0.5 to 2x2 cm or more are visible in the pulp. Even in healthy people, this watermelon causes nausea, vomiting, stomach pains and diarrhea. It is even more dangerous for young children and kidney patients. Children may have diarrhea, in some cases - convulsions and dehydration. In renal patients, renal colic and a sharp deterioration in health very quickly develop.

Eggplant. When the eggplants are fully ripe, the amount of the alkaloid solanine M increases sharply in them, so young and small fruits should be eaten. In case of poisoning with mature fruits, nausea, vomiting, diarrhea, intestinal colic, eclipse of consciousness, convulsions, shortness of breath occur. Help in case of poisoning: before the arrival of the doctor: the patient is given milk, mucous soups, egg white.

Hawthorn. Long-term and uncontrolled intake of hawthorn or drugs developed on its basis can cause depression of the heart rate, therefore, treatment with hawthorn must be carried out under the supervision of a physician. Taking hawthorn fruit on an empty stomach often causes intestinal spasm. After taking it, you can not drink cold water so as not to provoke the onset of intestinal colic.

Grape. It is better to eat grapes not earlier than 2 days after cutting from the bushes, since fresh, just picked grapes cause the formation of a large amount of gas (this is especially important to remember for people suffering from diseases of the stomach, intestines, kidneys and urinary tract). Such patients should drink only grape juice, and throw away the peel. Treatment with grapes is contraindicated in a number of chronic diseases, such as diabetes mellitus, diseases of the gastrointestinal tract, etc. Therefore, self-medication with grapes is best avoided. In this case, it is advisable to seek medical advice. In addition, grapes cause tooth decay, so after eating it, you should rinse your mouth with water and a little soda.

Pear. As with any fruit, the pear should not be overused. It should be eaten in moderation, not on an empty stomach, and not immediately after a meal, but 0.5-1 hour after a meal. After you have eaten a pear, do not drink raw water or eat dense and heavy foods.

Wild strawberries. Some people have hypersensitivity to strawberries, which causes an allergic reaction with persistent urticaria (pruritus). In this case, you cannot use strawberries.

Melon. Overeating melon can lead to intestinal dysfunction. Melon is contraindicated in diabetes mellitus, gastric ulcer and duodenal ulcer, dysentery and other intestinal disorders. Melon should not be combined with alcoholic beverages, honey, or washed down with cold water. This can cause bloating, intestinal colic, and severe diarrhea. Melon is also contraindicated in nursing mothers, as diarrhea can occur in the baby.

Fig. Due to the high sugar content, figs are contraindicated in patients with diabetes mellitus, in acute inflammatory diseases of the gastrointestinal tract. Figs are also contraindicated for gout, as they contain a lot of oxalic acid.

White cabbage. Cabbage should not be eaten by people with high acidity of gastric juice and diseases of the pancreas.

Potato. One feature of potato tubers should be warned - they must be stored in a dark place. Otherwise (if the tubers lie in the light, especially in the sun), they become poisonous, unsuitable for food use. Tubers clearly declare their changes themselves - they turn green in the light. Poisonous substances are formed only in this green surface of the potato, without penetrating into the depths. Another inconvenience that we face when storing potatoes is the appearance of white stolons - "sprouts". At the same time, the nutritional quality of the tubers does not significantly deteriorate, so you should not be afraid of sprouts (when peeling potatoes, they will still go to waste). But when cooking potatoes "in their uniforms," the sprouts must be broken off, since they contain the same toxic substances as in the green tubers.

Kinza. As a green seasoning, cilantro should not be used for stomach ulcers, coronary heart disease, thrombophlebitis, diabetes mellitus, hypertension. In addition, when nitrogen fertilization is excessively introduced into the soil, plants accumulate nitrates, sometimes causing food poisoning.

Hazelnuts (hazelnuts) Hazelnuts are good only in small quantities. It is enough to eat a little more than usual and the person will soon have headaches in the middle of the head. This is due to the fact that taking nut kernels causes spasm of the cerebral vessels.

Lemon. Lemon and products based on it are non-toxic. However, they can harm patients with gastritis, gastric ulcer and 12 duodenal ulcer. Their lemon causes heartburn, severe spastic pains and even vomiting. So such patients should eat lemons only in small quantities (1-2 slices) with tea and only after meals.

Onion. Excessive consumption of fresh onions can provoke an exacerbation of diseases of the stomach, kidneys and liver.

Raspberries. Raspberry fruits should not be eaten with gout and nephritis.

Carrot. Do not eat root crops and the tops of root crops that are on the surface of the earth and have a green color. They negatively affect the activity of the heart.

Sea buckthorn. Sea buckthorn oil is contraindicated in diseases of the gallbladder, gastrointestinal tract and pancreas. Fresh fruits and sea buckthorn juice contain a lot of acids, so they should not be used for gastric ulcer and duodenal ulcer.

Cucumber. Salted and pickled cucumbers should not be eaten by patients suffering from gastrointestinal ailments with increased acidity of gastric juice, hypertension, as well as atherosclerosis, hypertension, heart defects. Pickled and pickled cucumbers stimulate the appetite, so they are contraindicated in obesity.

Walnut. Nut fruits can cause allergic reactions (urticaria, allergic stomatitis, diathesis, etc.). Walnut fruits are harmful to patients who have skin diseases such as eczema, psoriasis and neurodermatitis. Taking even a small amount of nuts contributes to the exacerbation of these diseases.

Capsicum. Bitter pepper should not be used for hemorrhoids, for diseases of the stomach, intestines, especially for stomach ulcers, liver diseases (cirrhosis, acute and chronic hepatitis) and kidneys (acute and chronic nephritis and nephrosis).

Sweet pepper (Bulgarian). Contraindicated in patients with severe ischemic disease (angina pectoris), heart rhythm disturbances, hypertension, gastric ulcer and intestinal ulcers, suffering from gastritis with increased acidity of gastric juice, colitis, with exacerbation of chronic liver and kidney diseases, hemorrhoids, with increased excitability of the nervous system; with epilepsy and insomnia.

Peach. Peach, due to its high sugar content, cannot be eaten by diabetics.

Parsley. During pregnancy, parsley should not be consumed, there is a risk of miscarriage.

Rhubarb. Rhubarb should not be given on an empty stomach to patients with hyperacid gastritis or gastric ulcer and 12 duodenal ulcer. These patients usually experience severe stomach pains 10-15 minutes after taking rhubarb. Rhubarb should not be used by patients with nephrolithiasis. It is dangerous to use rhubarb for children and pregnant women.

Black radish. Internal use of radish is contraindicated for "heart" and "liver" patients, with gastric ulcer and 12 duodenal ulcer, inflammation of the gastrointestinal tract.

Beet. When fresh beet juice is taken, a strong spasm of blood vessels occurs. Therefore, the freshly squeezed juice should be allowed to stand for 2-3 hours so that the harmful volatile fractions "go away". After that, you can drink it. Beet juice should not be consumed with yeast bread or washed down with any sour juice. It is best to take it on an empty stomach, slightly warmed up 10-15 minutes before meals. Beet juice should be drunk in small sips, holding it in the mouth for a longer time. For patients with a sensitive stomach, the juice of raw beets should be mixed with oatmeal.

Tomato (tomato). Eating a lot of tomatoes leads to the formation of kidney stones.

Chokeberry. Excessive consumption of chokeberry is unsafe with increased blood clotting - it can lead to the formation of blood clots in the blood vessels. In addition, treatment with juice and fruits is not recommended for increased blood clotting, gastric ulcer and duodenal ulcer, as well as gastritis.

Garlic. Garlic should not be used by patients with epilepsy, hypertension, kidney inflammation, as well as pregnant women.

Sorrel. Sorrel is not recommended for use in case of salt metabolism disorders (rheumatism, gout) and related diseases, with intestinal inflammation and tuberculosis. Never eat boiled sorrel as it contributes to the development of arthritis.

ChapterIII

III. IHarm and benefitwatermelons

Let us analyze the benefits and harms of fruits using a specific example of watermelons.

The watermelon originates from the wild plants of tropical Africa. Botanists consider the Namib desert and the Kalahari semi-desert to be the center of origin of botany, where you can still find thickets of wild watermelon in the valleys. The modern watermelon is a descendant of huge perennial woody vines that live in the humid tropics. In Ancient Egypt, watermelon as a cultivated plant was known 4000 years ago. However, then it was grown not at all because of the juicy and sweet pulp, but to obtain a very valuable oil from its seeds. In Europe, the watermelon ended up after the Crusades. It was brought to Russia in Vstrongstrongstrong-X centuries from India during the time of lively trade with Kievan Rus. Initially, it took root in the Volga region, and by the XVstrongstrong century it was widely spread and grown even in the central regions as a greenhouse culture.

The most popular watermelons in Russia are definitely Astrakhan. This is a kind of brand, a guarantee of taste and quality. Merchants are well aware of this and often shamelessly take advantage of the gullibility of inexperienced buyers. However, nature is used to doing everything on time, and if watermelons are supposed to ripen by mid-late August, then it will be so. A reasonable question may arise: where do these delicious berries come from in our cities at the end of July?

Indeed, in Astrakhan, the trial harvesting of watermelons takes place in early August, selective - in the middle of the month, but the mass one starts on the 25th, so the native striped “Astrakhanians” should appear in Moscow only by September.

Option one: early ripening varieties from other watermelon-bearing regions of Russia and neighboring countries, but this option is unlikely, because they have not yet entered widespread practice, in addition, even for them, according to the All-Russian Research Institute of Irrigated Vegetable and Melon Growing (VNIIOB), located in Astrakhan region, 53-55 days are needed with a temperature of 25-30.C. It does not pose any threat to health, only benefits, but more on that below.

Option two: mid-season varieties (traditional Astrakhan watermelon), spurred on by nitrogen fertilizers and, above all, ammonium nitrate. This option is more common and completely indifferent to health. Let us consider it in more detail.

Watermelon is a dietary product. In the sense that there are practically no contraindications for the use of watermelon. Watermelon consists of water (up to 80 percent of the fruit weight), fructose, a small amount of glucose, sucrose, trace elements and plant fiber. Fructose is unique in that it is absorbed by the body without the need for insulin at all. This means that even patients with insulin-dependent diabetes can eat sweet watermelon.

The striped delicacy also has a pronounced diuretic effect, literally washing the body from the inside, which makes it possible to recommend the fragrant pulp to those suffering from diseases of the heart, blood vessels and joints. Watermelon cores are also useful for a reason, which we will talk about in the next section.

Watermelon is a real treasure of magnesium, without which a person simply cannot do. Chronic lack of magnesium in food leads to high blood pressure. Magnesium and its companion, calcium, provide for the narrowing and dilation of blood vessels, a mechanism that maintains the stability of blood pressure in the body.

Magnesium is important for bile secretion and cholesterol deactivation, for binding oxalic acid salts (oxalates) and preventing the formation of kidney stones, for reducing nervous excitability, relieving muscle spasms, and normalizing intestinal motility.

And this wonderful trace element in 100 grams of watermelon pulp contains as much as 224 milligrams - more only in almonds. Thus, in order to pay off the daily human need for magnesium, it is enough to eat 150 grams of watermelon.

Watermelon is also rich in potassium, although it is less than in dried apricots, bananas and persimmons, but if we compare the calorie content of the same bananas and watermelon, then the “Russian” grown on melons is clearly in a more advantageous position - there are three times more calories in a banana.

But despite all this many advantages, watermelons also have a number of negative qualities. For example, nitrates. They act on watermelons as steroid anabolic steroids for bodybuilders: growth is accelerated and an impressive weight and volume of the fetus is gaining very quickly. Everything would be fine, but nitrates categorically refuse to leave the watermelon. And acute nitrate poisoning at this time of the year is by no means uncommon. It is especially difficult in children, since nitrates compete with oxygen for our hemoglobin. And instead of carrying oxygen, hemoglobin (in the form of methemoglobin) causes serious problems with cellular respiration.

Nitrates have another bad feature.- accumulate in the body, causing chronic intoxication. Doctors call this the "cumulative effect." Children overloaded with nitrates grow worse, get sick more often, adults become irritable, sleep worse.

The most interesting thing is that it is almost impossible to distinguish a "pumped-up" watermelon from a normal one by eye. Special measuring devices that determine the content of nitrates in fruits and vegetables, like the portable "Marion", can help.

Products	Sugar content in%
glucose	fructose	sucrose
Apples	2,5-5,5	6,5-11,8	1,5-5,3
Pears	0,9-3,7	6,0-9,7	0,4-2,6
Quince	1,9-2,4	5,6-6,0	0,4-1,6
Apricots	0,1-3,4	0,1-3,0	2,8-10,4
Peaches	4,2-6,9	3,9-4,4	5,0-7,1
Plums	1,5-4,1	0,9-2,7	4,0-9,3
Cherries	5,3-7,7	3,4-6,1	0,4-0,7
Cherry	3,8-5,3	3,3-4,4	0,2-0,8
Red currants	1,1-1,3	1,6-2,8	0
Black currant	3,3-3,9	4,0-4,8	0,2-0,4
Gooseberry	1,2-3,6	2,1-3,8	0,1-0,6
Raspberries	2,3-3,3	2,5-3,4	0-0,2
Grape	7,2	7,2	0
Bananas	4,7	8,6	13,7
Pineapple	1,0	0,6	8,6
Persimmon	6,6	9,2	0

Cellulose

Fiber is widely found in fruits and vegetables, reaching 1-2% of their composition. There is especially a lot of fiber in berries (3-5%).

Fiber, as you know, refers to substances that are difficult to digest by the digestive apparatus. Vegetables and fruits are a source of predominantly delicate fiber (potatoes, cabbage, apples, peaches), which is broken down and absorbed quite fully.

In the light of modern scientific concepts, fiber of vegetables and fruits is considered as a substance that promotes the elimination of cholesterol from the body, as well as has a normalizing effect on the vital activity of beneficial intestinal microflora.

Plants play an extremely important role in human nutrition, supplying the body with all the necessary substances. Almost all the variety of substances contained in plants is formed from carbohydrates, which, in turn, are formed from carbon dioxide and water under the influence of solar energy in the process of photosynthesis. Nitrogenous and mineral substances enter plants from the soil.

Certain types of fruits and vegetables differ in the qualitative and quantitative composition of their chemical components, but they are all characterized by an insignificant dry matter content and, accordingly, a high water content, which determines their behavior during storage and processing. Fruits contain more dry matter (10 ... 20%) than vegetables (5 ... 10%). Only some types of vegetables are characterized by a relatively high dry matter content (green peas - up to 20%, potatoes - up to 25%). Of particular importance are the essential components of food contained in significant quantities in fruits and vegetables - water- and fat-soluble vitamins, macro- and microelements, and in smaller quantities - essential fatty acids and amino acids.

Carbohydrates. In fruits and vegetables, carbohydrates make up 80 ... 90% of the dry mass. For humans, carbohydrates are the main source of energy necessary for the vital activity of all tissues and organs, as well as plastic material.

Of carbohydrates, fruits and vegetables contain monosaccharides (mainly glucose and fructose) and polysaccharides (polyoses) of the first (mainly sucrose disaccharide) and second (starch, cellulose, hemicellulose, pectin) orders. In addition, they contain small amounts of monosaccharides of mannose, arabinose, sorbose, xylose, ribose, galactose and polyhydric alcohols (sorbitol and mannitol), which, when oxidized, can form glucose, fructose, etc.

Monosaccharides and first-order polysaccharides are simply called sugars. The sugar content in fruits averages 8 ... 12%, but in some species it reaches 15 ... 20% (grapes, persimmons, bananas). Sugars in vegetables contain on average 2 ... 6%.

Sugars are well absorbed by the human body and, with excessive consumption of carbohydrates (especially sucrose), lead to a sharp rise in blood glucose levels. The consumption of fructose slows down this process, therefore it is important for the nutrition of patients with diabetes mellitus, since enzymes take part in its metabolism, the activity of which does not depend on the presence of insulin. Eating foods that are sources of fructose is also preferable because glucose and fructose have different degrees of sweetness. If we take the sweetness index of sucrose as 100, then for fructose it will be 173, and for glucose 74. Therefore, to obtain the same taste of the product, fructose needs much less than glucose or sucrose.

There is a concept of the threshold for the sensation of sweetness, that is, the minimum concentration at which a sweet taste is felt. For glucose, the sweetness threshold is 0.55%, for sucrose - 038%, and for fructose - 0.25%. Fruits in which fructose predominates over glucose include apples, pears, watermelons, melons, black currants, etc. From vegetables, such a source is an earthen pear (Jerusalem artichoke), which contains the polysaccharides inulin (about 14%), sinanthrine, etc., which hydrolysis gives fructose. So, during the hydrolysis of inulin, 94 ... 97% of fructose and 3 ... 6% of glucose are formed.

The taste of fruits and vegetables depends not only on the content of sugars, but also on the presence of other components in them - acids, phenolic compounds, essential oils, glycosides, alkaloids and other substances. There is an indicator of the taste of fruits and vegetables - the sugar-acid index, which is understood as the ratio of the percentage of sugar to the percentage of acid.

Sugars are considered relatively stable compared to other components of fruits and vegetables, such as vitamins. But they also undergo changes in the process of technological processing. The disaccharide sucrose can undergo hydrolysis in aqueous solutions in the presence of an acid to form an invert sugar - a mixture of glucose and fructose.

Sugars are readily soluble in water and are hygroscopic, especially fructose, which implies their storage in sealed packaging or in conditions of low air humidity. Loss of sugars due to their good solubility can occur during washing, steeping, blanching of raw materials.

Starch in plants is in the amyloplasts of cells in the form of starch grains, which differ in chemical composition and properties. Starch grains have an oval, spherical or irregular shape with a size of 0.002 ... 0.15 mm. Starch accumulates mainly in the tubers and grains of vegetables. In potatoes, the starch content is on average 18%, in green peas - about 7, in beans - 6, and in most other fruits and vegetables - less than 1%.

The carbohydrate part of starch is represented by two types of polysaccharides - amylose (about 20%) and amylopectin (about 80%), which differ in their chemical structure and properties. The content of amylose and amylopectin varies depending on the variety and part of the plant from which the starch is obtained. Apple starch, for example, consists only of amylose. During acid hydrolysis, starch decomposes with the addition of water, forming glucose:

(C 6 H 10 O 5) NS + (n-1) H 2 O → NS S 6 N 12 O 6

Amylose is readily soluble in water and gives solutions of relatively low viscosity. Amylopectin dissolves only in warm water and gives very viscous solutions.

During enzymatic hydrolysis under the action of the enzyme amylase, starch is saccharified with the formation of maltose. Various dextrins (amylodextrin, erythrodextrin, etc.) are formed as intermediate products, which differ little from starch in molecular size and properties. Maltose is converted into glucose by the enzyme maltase.

Starch is insoluble in cold water. With increasing temperature, starch swells, forming a viscous colloidal solution. When cooled, this solution forms a stable gel called a paste. The gelatinization of starch solutions worsens the heat exchange conditions and affects the duration of technological processes associated with the heat treatment of products.

Cellulose (fiber) is a polysaccharide that is the main constituent of the cell walls of fruits and vegetables. The cellulose content depends on the type of plant, accounting for most fruits and vegetables 1..2%, and in beans, zucchini, cucumbers, watermelons, melons, cherries - only 0.1 ... 0.5%.

Cellulose is insoluble in water. With complete acidic hydrolysis of cellulose, practically only glucose is formed, with incomplete hydrolysis, cellobiose and other decomposition products.

Cellulose is not digested by human intestinal enzymes, but plays an important role as a stimulant of intestinal motility. It is included in the set of substances that make up an extremely important part of human food - dietary fiber. The main components of dietary fiber in fruits and vegetables are polysaccharides (cellulose, those cellulose, pectin) and lignin. Cellulose and other ballast substances contribute to the binding and elimination of certain metabolites from the body, for example, sterols, including cholesterol, normalization of the intestinal microflora, and prevent the absorption of toxic substances.

At the same time, the high content of cellulose in food makes it coarse and less digestible. Raw materials for the production of canned food for children and diet are selected with a lower cellulose content (zucchini, pumpkin, rice). The high cellulose content also interferes with a number of technological processes (wiping, boiling, sterilization).

Cellulose has moisture retention and sorption capacity. The product of partial hydrolysis of cellulose is microcrystalline cellulose, consisting of aggregates of macromolecules with a high ratio of length to thickness (length 1 micron and thickness 0.0025 micron), is used to clarify citrus juice, extract essential oils from plants, etc.

Hemicelluloses form the walls of plant tissues. The group of hemicelluloses includes various xylans, arabinans, mannans, and galactans. The content of hemicelluloses in fruits and vegetables averages 0.1 ... 0.5%, slightly more in beets (0.7%), grapes (0.6%).

Hemicelluloses are insoluble in water, but they dissolve well in alkaline solutions and hydrolyze in aqueous solutions of acids. Hydrolysis produces sugars (mannose, galactose, arabinose or xylose). Like cellulose, hemicelluloses are found in dietary fiber.

Pectin substances are found in all parts of plants, being a part of cell walls and intercellular formations (median plates) of tissues of fruits and vegetables. They are also found in the cytoplasm and sap of plant cell vacuoles. In the cell wall, pectin substances are associated with cellulose, hemicelluloses, and lignin. Fruits and vegetables contain on average 03-1% of pectin substances. Most of them are found in apples (1.0%), black currants (1.1%), gooseberries (0.7%), beets (1.1%).

Pectin substances are mainly composed of galacturonic acid residues, which form a long molecular chain. Depending on the degree of esterification, pectin can be highly or low-esterified, that is, it is partially or completely methoxylated polygalacturonic acid. For example, apples are characterized by a high degree of esterification.

In plants, pectin substances are present in the form of insoluble protopectin, which is a methoxylated polygalacturonic acid associated with galactan and araban of the plant cell wall. Protopectin plays the role of a cell-bonding substance, being part of the median plates; in a swollen state protects the cytoplasm of the cell from dehydration. As most fruits ripen, the amount of protopectin decreases and it turns into soluble pectin, which explains the softening of the fruit tissue.

As a hydrophilic colloid, soluble pectin increases the water-holding capacity of the cell, the state of its turgor. The technological properties of pectin are due to its ability to dissolve in water. The solubility of pectin depends on the degree of polymerization (molecular size) and esterification. Pectin with a lower molecular weight (short chain) and a large number of methoxyl groups dissolves more easily.

From protopectin, under the action of the enzyme protopectinase or dilute acids, soluble pectin is formed, consisting of partially methoxylated polygalacturonic acid residues. Soluble pectin in the presence of sugar and acid gives jellies, due to which it is used in the food industry for the production of jelly, jam, marmalade, jams, sweets.

During alkaline or enzymatic hydrolysis, soluble pectin easily loses almost all methoxyl groups and turns into free pectic (polygalacturonic) acid, which is already practically insoluble in water and is not capable of producing jellies in the presence of sugar. With complete demethoxylation, pectins are converted into completely insoluble pectin acids.

Pectin has important biological properties due to the presence of free carboxyl groups of galacturonic acid capable of binding heavy metals, including radionuclides, to form insoluble complexes that are removed from the body. It is this ability of pectin substances to adsorb heavy metals that determines their value in preventive and dietary nutrition.

Pectin substances also regulate cholesterol content, increase resistance to allergic factors. For the manufacture of pectin-containing products of dietary, preventive and therapeutic nutrition, various fruits and berries (apples, quince, strawberries, etc.) are used with the addition of dry pectin or pectin concentrate (apple, citrus, beet). At the same time, the presence of pectin substances in fruits complicates some technological processes, for example, clarification and filtration of fruit juices.

Proteins and other nitrogenous substances. Fruits and vegetables contain relatively little protein. The biological value of proteins is determined by the presence of essential amino acids in their composition, which are not synthesized in the body and must be supplied with food. Of the 20 natural amino acids, eight are essential: lysine, methionine, tryptophan, phenylalanine, leucine, isoleucine, threonine, and valine. At present, they also include histidine and arginine, which are not synthesized in the child's body.

Along with proteins, fruits and vegetables contain free amino acids, nucleic acids (DNA and RNA), glycosides, ammonium salts and other non-protein nitrogenous substances. The content of the latter in vegetables is higher (on average 2 ... 5%) than in fruits (less than 1%). There are relatively many proteins in beans (6%), green peas (5), Brussels sprouts (4.8), parsley (greens 3.7%). The proteins in many vegetables contain all the essential amino acids.

The structure and physicochemical properties of proteins affect the technological processes of processing fruits and vegetables. Being high molecular weight hydrophilic compounds and amphoteric electrolytes, proteins form stable colloidal solutions, complicating the processes of obtaining and clarifying juices. The destruction of the colloidal system of proteins can be caused by the action of factors that contribute to the dehydration of protein globules and the neutralization of charges on their surface. To do this, use heating, treatment with acids, salts, alcohol, tannin, electric current, etc.

Lipids. The content of lipids (fats) in fruits and vegetables, unlike animal products, is insignificant, so they cannot be considered a source of these substances for humans. At the same time, lipids perform a number of important functions in the body: they are sources of energy and solvents of vitamins A, D, E, K, promoting their assimilation.

Fats accumulate in large quantities in plant seeds, which are used to make vegetable oils. Vegetable oils contain up to 99.7% fat, have a low melting point, therefore they are easily digestible (97 ... 98%) .

Organic acids. In fruits and vegetables, organic acids are in free form or in the form of salts, giving them a specific taste and promoting better digestibility. The sour taste of a product depends not only on the total content of acids, but also on the degree of their dissociation, that is, on the pH value (active acidity), which for most fruits and berries averages about 3-4, for vegetables - 4-6 ,5. Depending on the pH value, fresh fruits and vegetables are divided into acidic (pH 2.5-4.2) and non-acidic (pH 43-6.5).

The acidity of fruits and vegetables affects a number of technological processes - the choice of the sterilization mode for canned food, cooking jelly, the production of juices, etc. For example, canned food from non-acidic raw materials, in which bacilli and clostridia can develop, must be sterilized at temperatures above 100 ° C.

Acidity is one of the indicators of the good quality of fruits and vegetables. The value of this indicator determines the harmonious taste of the product, its sugar-acid index (the ratio of the percentage of sugar to the percentage of acid). In the human body, acids, except for oxalic, dissolve unwanted salts and remove them from the body ...

In fruits and vegetables, malic, citric and tartaric acids are most often found, oxalic, succinic, salicylic, benzoic, etc. are present in smaller amounts. Malic acid predominates in stone and pome fruits (0.4 ... 13%); among vegetables, the largest amount of it is found in tomatoes (0.24%). There is a lot of citric acid in citrus fruits, especially in lemons (5.7%), black currants and cranberries (1 ... 2%). Tartaric acid is found in large quantities in grapes (up to 1.7%). Oxalic acid is abundant in sorrel, rhubarb, spinach, and a small amount of it is found in tomatoes, black currants, onions, carrots.

Most of the listed acids and their salts are readily soluble in water. Medium calcium salt of citric acid and acidic potassium hydrogen tartrate (tartar) are poorly soluble in water; The calcium salt of oxalic acid (calcium oxalate) is insoluble in water, so it can precipitate, forming stones (oxalates). Of the volatile sour in fruits and vegetables, acetic and formic are found in small quantities.

Polyphenolic compounds. Fruits and vegetables contain a variety of polyphenolic substances, including monomeric (flavonoids, derivatives of cinnamic and phenol carboxylic acids) and polymeric (tannins).

Flavonoids, which include a number of flavan derivatives (catechins, leukoanthocyanins, anthocyanins, flavones, flavonols, flavanones), are found in fruits and berries. Polymeric forms of flavonoids, as well as low molecular weight compounds with a tart astringent taste. In technical biochemistry and technology, they are often called tannins. The content of tannins in most fruits and berries is 0.05 ... 0.2%, in vegetables they are even less. A lot of tannins are found in blackthorn (up to 1.7%), quince (up to 1), dogwood (up to 0.6), black currant (03-0.4%), in the fruits of wild apples and pears.

Tannins are subdivided into hydrolyzable and condensed. Hydrolyzable tannins decompose in an acidic environment to simpler compounds. For example, gallotannin is broken down into glucose and gallic acid. Condensed tannins are not well understood. Unlike hydrolyzable tannins, they do not hydrolyze; when heated in an acidic medium, they undergo further compaction, and are derivatives of catechins or leukoanthocyanins.

The catechins have been studied most fully. Their characteristic feature is the addition of gallic acid residues, high P-activity. A large number of catechins are found in the tea leaf, there are also many of them in apples, hawthorn, cranberries, blueberries.

Tannins, despite the relatively low content in fruits and berries, significantly affect their technological characteristics. They are easily oxidized with the participation of polyphenol oxide ases in the presence of atmospheric oxygen with the formation of first quinones, and then dark-colored substances - flobaphenes. To prevent this undesirable phenomenon, it is necessary to inactivate the enzyme systems of the fruits, isolate them from atmospheric oxygen or treat them with sulfur dioxide.

Darkening of the pulp of fruits or juice can also be a consequence of the interaction of tannins with iron salts, tin, zinc, copper and other metals. On prolonged heating, tannins can condense to form red compounds. The ability of tannins to give insoluble compounds with proteins and to precipitate them is used in the production of juices.

Pigments. The composition of fruits and vegetables contains various pigments that give them color (dyes), especially the outer layers and integumentary tissues. Many pigments are flavonoids and are highly soluble in water (anthocyanins, flavones, flavonols).

Anthocyanins are dyes in plants that give them a color from pink to black-violet. Unlike chlorophyll, they are concentrated not in plastids, but in cell vacuoles, present in tissues in the form of glycosides, which, upon hydrolysis, give sugar and colored aglycones - anthocyacidins.

Of this group of coloring substances, cyanidin is known, which is part of apples, plums, cherries, grapes, red cabbage, keracyanin - cherries and cherries, enin - grapes, idein - lingonberries, betaine - beets. Anthocyanidins are amphoteric and pH sensitive: the lower the pH of the medium, the better the natural color of the processed fruit retains.

Some metals affect the color of anthocyanins: under the influence of tin, cherries, plums, cherries acquire a purple hue; iron, tin, copper, nickel change the color of the grapes. Prolonged heating of the fruit can also lead to the destruction of anthocyanins and loss of color (strawberries, cherries).

Flavones and flavonols are yellow dyes that form many different glycosides, which, upon hydrolysis, give colored aglycones: apigenin (parsley, orange), quercitrin (grapes), quercitrin (onions), etc.

Chlorophylls are pigments that are insoluble in water, but dissolve in fats. Chlorophylls play an extremely important role in the process of photosynthesis, give green color to plants, and are concentrated in plastids (chloroplasts) of cells. The chlorophyll content reaches 0.1%. Higher plants and green algae have two types of chlorophyll - chlorophyll a and chlorophyll v.

The transformation of chlorophylls during canning of fruits and vegetables can also affect their color change. When heated in an acidic medium, chlorophyll magnesium is mixed with hydrogen to form pheophytin, which has a green-brown color. When heated in an alkaline medium, chorophyllides of an intense green color are formed. Metal ions act in a similar way: iron gives chlorophyll a brown color, tin and aluminum - gray, copper - bright green.

Carotenoids are pigments that give fruits and vegetables their yellow, orange and red color. These include primarily carotene, lycopene and xanthophyll. The content of carotenoids in fruits and vegetables is different: in mature tomatoes, on average 0.002 ... 0.008%, red lycopene prevails among them. There are many carotenoids in carrots, apricots, peaches, leafy vegetables, where they are masked by chlorophyll. Xanthophyll is found in citrus peels, corn.

In plants, carotenoids accompany chlorophyll and protect it from destruction. The energy absorbed by carotenoids is used for photosynthesis. Carotene is characterized by the presence of a β-ionone ring in the molecule, which determines its vitamin properties. In the human body, carotene is converted to vitamin A.

Glycosides... In plants, glycosides are ether-type compounds formed by monosaccharides by combining their glycosidic hydroxyl with a non-carbohydrate alcohol (aglycone). The aglycone can be a wide variety of compounds (alcohols, aldehydes, phenols, sulfur and nitrogen-containing substances, etc.), on which the properties of glycosides depend. Some of the aglycones are highly toxic.

Glycosides are soluble in water and alcohol. During hydrolysis in an acidic medium or with the participation of enzymes, they are broken down into sugar and the corresponding aglycone. Many of the glycosides have a bitter taste or specific aroma. In fruits and vegetables, glycosides are most often found in the skin and seeds, less often in the pulp.

The following glycosides are known: amygdalin (in the seeds of stone fruit and pome fruits), hesperidin and naringin (in the pulp and peel of citrus fruits), solanine (in potatoes, eggplants, tomatoes), vaccinin (in lingonberries, cranberries), apiin (in parsley), glucose acid (in gooseberries, apples, plums, cherries, etc.). Glycosides also include tannins (hydrolyzable) and fruit dyes - anthocyanins.

Amygdalin (C 20 H 27 NO 11) is one of the most toxic glycosides. The toxic properties of amygdalin appear after its acidic or enzymatic hydrolysis (with the participation of emulsin contained in the seeds) and the formation of hydrocyanic acid. To prevent amygdalin poisoning, it is necessary to limit the consumption of raw kernels or subject them to heat treatment.

Solanines (glucoalkaloids) are glycosides containing an aglycone of a steroid nature. The composition of potato solanins (C 45 H 71 NO 15) contains the same aglycone solanidin, and the sugars can be different (residues of glucose, galactose or rhamnose).

Hesperidin - a flavanone glucoside - causes a very high P-vitamin activity of citrus fruits. Naringin imparts bitterness to citrus fruits, especially unripe fruits. You can remove the bitterness by heating the fruit in an acidic environment. As a result of hydrolysis of naringin, naringenin aglucone is formed, which does not have a bitter taste.

Aroma-forming substances. Of these substances, plants most often contain oxygen-containing derivatives of terpenes - aldehydes and alcohols, as well as other volatile compounds that make up the so-called essential oils. They are formed and secreted mainly in the glandular hairs (scales) of the fruit skin, giving them a characteristic aroma.

Essential oils are in most cases insoluble in water, but dissolve in organic solvents. They are volatile and therefore can be lost during heat treatment of raw materials.

The most common essential oils are: limonene (citrus fruits, dill), carvone (cumin, parsley, dill), linalool (citrus fruits, coriander). Some essential oils have bactericidal properties and are formed only after mechanical tissue damage (allicin of garlic and onion). Before that, they are in the form of glycosides and are physiologically inactive. After cell damage, previously uncoupled glycosides and hydrolytic enzymes come into contact, resulting in the release of essential oils.

Minerals. Fruits and vegetables are an essential source of minerals in the human diet. Many elements are part of living matter as a plastic material, take part in hematopoiesis, are constituents of a number of vitamins, enzymes and hormones.

All minerals, depending on their content in the body and the need for them, are divided into macro- and microelements. The need for macronutrients (sodium, potassium, calcium, magnesium, phosphorus, chlorine, sulfur, etc.) is calculated in grams, and for microelements (iron, cobalt, zinc, iodine, fluorine, copper, manganese, etc.) - in milligrams or micrograms per day. The content of trace elements in fruits and vegetables is within thousandths of a percent.

Minerals in fruits and vegetables are in a form that is easily assimilated by the human body. The content of minerals in fruits and vegetables is determined by the amount of ash formed after burning. It ranges from 0.2 to 2.3% - Of the vegetables, dill (2.3%) and spinach (13%) give the most ash.

Vitamins. Fruits and vegetables are suppliers of vitamins for humans. Vitamins are a group of organic substances of different chemical structure, differing in biological activity.

According to their solubility, vitamins are subdivided into water-soluble and fat-soluble. From water-soluble fruits and vegetables contain vitamins C, B 1, B 2, B 3, B 5 (vitamin PP), B 6, B c (folic acid), H (biotin); from fat-soluble-A, E, K; from vitamin-like substances - vitamins P (citrine), B 4 (choline), B 8 (inositol), U (methylmethionine sulfonium).

Vitamin C (ascorbic acid) takes part in metabolic processes as a hydrogen carrier, easily converting from hydroform to dehydroform (dehydroascorbic acid). This process is reversible and both forms are physiologically active. But dehydroascorbic acid is less stable and, upon further oxidation, turns into diketogulonic acid, which is physiologically inactive.

Ascorbic acid prevents scurvy disease, promotes the oxidation of cholesterol, and strengthens the body's immune system. The content of vitamin C in most fruits and vegetables averages 20 ... 40 mg / 100 g. It is especially abundant in sweet peppers (150 ... 250 mg / 100 g), black currants (up to 200 mg / 100 g). Rich in vitamin C parsley (greens), cabbage, citrus fruits, strawberries (garden), poor - root crops, melons.

Vitamin C is very labile and easily destroyed as a result of oxidation, especially in an alkaline environment, when heated, dried, or exposed to light; oxidation is accelerated in the presence of iron, copper, and also with the participation of oxidative enzymes, in particular when grinding raw materials that promote the release of enzymes.

To reduce the loss of vitamin C during canning, the raw materials are blanched, processed under vacuum, short-term sterilized by high-frequency currents, and sulfitation. Freezing of raw materials and storage at a negative temperature provides a great effect, ensuring the preservation of about 90% of vitamin C.

Vitamin U (antiulcer factor) is also sensitive to prolonged heat treatment. Juices from raw vegetables, especially cabbage (16.4 ... 20.7 mg / 100 g), as well as fruit juices are rich in vitamin U.

Vitamin A (retinol) affects the growth of the body, the visual function of the eye, is contained in fruits and vegetables in the form of provitamins - carotenoids. Of several isomers of carotene (α, β, γ), β-carotene has physiological activity. β-Carotene are rich in orange or red vegetables, fruits and berries (carrots, apricots, tomatoes, pumpkin, currants), as well as parsley, green peas, spinach, etc.

When preserving raw materials, 0-carotene is relatively thermally stable, but sensitive to oxidation, especially when heated and exposed to light; unstable in an acidic environment. Since β-carotene does not dissolve in water, it is practically not lost during washing and blanching of raw materials.

B vitamins and vitamin K are more resistant to heat, the action of atmospheric oxygen, but are destroyed in an alkaline environment. Vitamin B 3 (pantothenic acid) is stable in a neutral environment, but rapidly degrades in hot acidic and alkaline solutions. Vitamins B2, B6, Bc (folic acid), K are destroyed by prolonged exposure to light, vitamins B2 and E are sensitive to ultraviolet radiation.

To maximize the preservation of vitamins during the processing of plant materials, the duration of high-temperature exposure to the product is reduced, air is removed from the product, the product is prevented from contacting metals that catalyze the oxidation process (copper, iron), enzymes are inactivated, an appropriate environmental reaction (pH) is created, and vitamin stabilizers are used, antioxidants, sulphitation, shorten the production cycle. Each of these techniques is implemented depending on the type of raw material and the final product. A particularly effective way of preserving vitamins is by freezing raw materials and storing them at low temperatures.

Most of the vitamins of fruits and vegetables, being sources of pectin substances, potassium, etc., also act as protective components that ensure the functions of barrier tissues (vitamins A, C, P, groups B, E, U), as components exhibiting an anticarcinogenic effect (vitamins (C, A, E, K), as substances that improve liver function (vitamins B 1, B 2, C R, PP). The main sources of protective components are carrots, beets, pumpkin, cabbage, leafy vegetables, black currants, gooseberries, rose hips, citrus fruits and other fruits.

Enzymes. These compounds are biological catalysts that regulate life processes in living organisms. Along with protein, many enzymes include a non-protein part (coenzyme). Many vitamins act as coenzymes (C, B 1, B 2, B 6, E, etc.).

Fruits and vegetables contain enzymes that play a positive role, for example, in the ripening of fruits. But there are those that, when storing and processing raw materials, can cause deterioration in the quality or damage to the product, the destruction of vitamins. So, some oxidative enzymes (ascorbine oxidase, polyphenol oxidase, etc.) act as antivitamins for ascorbic acid, especially when grinding raw materials. The enzyme polyphenol oxidase acts on polyphenols, tyrosine, as a result of which dark-colored compounds are formed, the product darkens, etc. etc.).

Fruit classification 1.

The class of fruits unites types of products, the edible organ of which is true and false fruits for dessert purposes. true fruits are those that have developed from the ovary into a juicy pericarp; false fruits are formed from an overgrown receptacle, the bases of the stamens, petals, and a bowl of leaves.

The class of fruits is divided into two subclasses: juicy and dry.

Juicy fruits, taking into account their structure, purpose and other characteristics, are divided into six groups:

Pome fruit;

Stone fruits;

Subtropical diverse;
Citrus;
Tropical.

Dried fruits are represented by nut-bearing fruits.

Classification of vegetables.

Vegetable plants are subdivided into annuals, biennials and perennials according to their lifespan. According to the method of harvesting, vegetables are ground and greenhouse-hothouse. According to the duration of the growing season, they are subdivided into early-ripening, mid-ripening and late-ripening.

According to botanical characteristics, the class of vegetables is divided into two subclasses - vegetative and fruit. In vegetative vegetables, the edible part is the vegetative organs of plants: roots, stems, shoots with leaves, buds and inflorescences. In fruits, only fruits.

Vegetative vegetables are classified into seven groups:

Tuber crops;

Roots;

Cabbage;

Salad spinach;
Spicy flavoring;
Dessert.

Fruit vegetables are divided into three groups:

Pumpkin;

Tomato;

Pulses.

1.2. The chemical composition of fresh fruits and vegetables, their nutritional value.

The chemical composition and physical properties of fresh fruits and vegetables are determined by the structure and composition of the tissues that form them.

In fruits and vegetables, as well as in the products of their processing, there are various substances: easily digestible sugars (glucose, fructose, sucrose), polysaccharides (starch, fiber, inulin), organic acids (malic, citric, tartaric, etc.), polyphenols , mineral salts, vitamins, nitrogenous, aromatic, coloring and pectin substances. Some substances are not essential for human nutrition, but play an important role in the vital processes of fruits and vegetables, such as aging, germination, disease resistance, etc. These include, for example, nucleic acids.

Some fruits and vegetables have medicinal value and are used in medicine. For example, raspberries, which contain salicylic acid, have good diaphoretic and diuretic properties; blueberries and pears have a firming effect, and plums have a laxative effect. The medicinal properties of cabbage juice in case of peptic ulcer disease, diabetes mellitus, hypertension, and of pectin substances - in case of intestinal diseases have been established. The medicinal properties of grapes, lemon, orange, strawberry, currant, garlic, onion, etc. are also well known.

The chemical composition of fruits and vegetables is not constant, but can change during their growth, ripening and depends on a number of factors: type, variety, degree of maturity, harvest time, marketable processing, storage duration, etc.

Water

It is part of all fruits and vegetables. while its content in some of them, for example in cucumbers, reaches 98%. The role of water for the quality and preservation of fruits and vegetables is extremely high.

Minerals .

Inorganic (mineral) substances are an integral part of mineral salts and organic compounds. They are present in all fruits and vegetables, playing an important role in metabolic processes and the building of tissues of the human body.

TO macronutrients include calcium, phosphorus, magnesium, potassium, sodium and sulfur.

Calcium (Ca) is necessary for the formation of bone tissue, maintenance of normal functioning of the nervous system and heart.

Phosphorus (F) takes part in the metabolism of proteins and fats. affects the functions of the central nervous system, is part of the bones.

Magnesium (Mg) has a vasodilating property, affects the nervous system, normalizes the activity of the muscles of the heart, improves its blood supply.

Sulfur (S) is part of some amino acids, vitamin B1, the hormone insulin, which regulates the absorption of glucose in the human body.

Trace elements - this is iodine, fluorine, manganese, copper, zinc, bromine, aluminum, chromium, nickel. Most micronutrients are as important for human nutrition as macronutrients.

Iodine (I) is essential for the normal functioning of the thyroid gland.

Fluorine (F) plays an important role in the formation of bones, teeth.

Manganese (Mn) takes an active part in hematopoiesis, bone formation, affects immunity and metabolism.

Copper (Cu) takes part in hematopoiesis.

Zinc (Zn) is a part of all tissues, affects the function of the pancreas and fat metabolism, promotes the growth of a young body, hair, nails.

Carbohydrates is a group of natural organic compounds that include carbon, hydrogen and oxygen. Carbohydrates are the primary products of photosynthesis and the main primary products of the biosynthesis of other substances in plants. Therefore, they are mainly found in plant foods. Carbohydrates make up an essential part of the human diet. In fruits and vegetables, they are presented in the following forms:

monosaccharides: glucose (grape sugar), fructose (fruit sugar), mannose (found in fruits);

Disaccharides : sucrose (beet sugar), maltose (malt sugar);

Polysaccharides : starch, fiber (cellulose), inulin;

Pectin substances : protopectin (an insoluble high molecular weight compound that determines the hardness of immature fruits and vegetables), pectin (a high molecular weight substance soluble in the cell juice of fruits that helps soften their tissues during ripening) pectic and pectic acid.

Protein - natural high-molecular organic compounds built from amino acid residues. In addition to amino acids, complex proteins include carbohydrates, amino acids, etc.

Fats - organic compounds, mainly esters of glycerol and monobasic fatty acids. It is one of the main components of cells and tissues of living organisms. Fats are the source of energy in the body.

Enzymes are special proteins that increase the rate of all chemical reactions in the cells of all living organisms. Enzymes are involved in the implementation of all metabolic processes, in the implementation of genetic information. Without the participation of enzymes, it is impossible to digest and assimilate nutrients, the synthesis and breakdown of proteins, fats, carbohydrates and other compounds in the cells and tissues of all organisms.

Organic acids - give food products taste, can improve their preservation, promote digestion.

Vitamins - are low molecular weight organic compounds of various chemical nature. In small quantities, they are necessary for the normal metabolism and vital activity of living organisms. All vitamins are subdivided into all groups:

Water soluble - B1 (thiamine), B2 (riboflavin), B3 (pantothenic acid), B6 (pyridoxine), B12 (cyanocobalamin), Bs (folic acid), C (ascorbic acid), PP (nicotinic acid);

Fat soluble - A (retinol), D (calciferols), E (tocopherols), H (biotin), K (phylloquinone).

Dyes (pigments) determine the color of fruits and vegetables.

Chlorophyll determines the green color of fresh fruits and vegetables.

Aromatic substances ... Fruits and vegetables contain various essential oils that give them their characteristic odor.

Phytoncides ... Phytoncides are biologically active substances formed by plants that kill or suppress the growth and development of microorganisms, in other words, strengthens the immunity of both plants and humans and animals.

The chemical composition of fresh fruits and berries depends on their type, degree of maturity, harvest time, storage methods, etc.

Fresh fruits and berries have a high water content - 72 - 96%. It determines the physiological processes in fruits and berries, and also contributes to the development of various microbiological processes that lead to their deterioration. When storing fruits, water can evaporate, which leads to a decrease in keeping quality and a decrease in their shelf life.

The main energy material of fruits and berries is carbohydrates- sugars, starch, cellulose (fiber), pectin substances, hemicellulose. The calorie content of carbohydrates is low, but the presence of sugars in fruits and berries, due to their easy digestibility, makes them especially useful for humans.

Of the sugars, fruits and berries most often and in the greatest amount contain glucose, fructose and sucrose. The total amount of sugars depends on many factors: crops, varieties, growing zones, agricultural techniques, soil and weather conditions, etc. The ratio of different sugars mainly depends on the type of fruits and berries. For example, apples and pears contain 6-12% fructose, 1-5% glucose and 0.5-5.5% sucrose; in apricots - respectively 0.1 - 3.2, 0.1 - 3.2 and 4.5 - 10%, and in cherries - 3.3 - 4.4, 3.8 - 5.3 and 0 - 0 ,eight %. The starch content in fruits and berries reaches 1%. Most of the starch is found in unripe apples. As the fruit ripens, it is hydrolyzed to form sugars and other substances.

The cell walls of fruits and berries are built mainly from cellulose (fiber), which is a polysaccharide. Its content in fruits and berries is about 1 - 2%. Fiber is almost not absorbed by the human body, but contributes to the normal functioning of the intestines.

Pectinsubstances are high molecular weight compounds of a carbohydrate nature. In fruits and berries, they are found in the form of pectin, protopectin and pectic acid. Their content in apples is 0.8 - 1.3%, in plums - 0.5 - 1.3, in raspberries - 0.1 - 0.7%. Protopectin is contained in the intercellular spaces and in the cell membranes, does not dissolve in water and determines the hardness of the fruit. As it matures, protopectin splits to form pectin and hemicellulose. This process takes place during the cooking of fruits, since at a temperature of 80 - 85 ° C protopectin is hydrolyzed. This property is used when blanching fruits to remove the skin from them.

Common organicacids, contained in fruits are apple, lemon and wine. Less often and in small quantities, fruits contain benzoic, salicylic, succinic acids, etc. The total acidity of fruits and berries ranges from 0.4 to 8%.

Certain types and varieties of fruits can simultaneously contain one, two or more acids. In stone and pome fruits, for example, malic and citric acids are found. Malic acid is especially abundant (up to 6%) in dogwood and barba rice. Citric acid is found mainly in lemons (up to 7%), cranberries and pomegranates. Tartaric acid predominates in grapes (0.3 - 1.7%). Benzoic acid is contained in a small amount (0.1%) in lingonberries and cranberries, salicylic acid - in raspberries and strawberries. Due to the fact that benzoic acid has antiseptic properties, cranberries and lingonberries are well preserved. There are few acids in cherries, pears, ab-ricos.

The taste sensation of acids in fruits is significantly influenced by Sahara, tanningsubstances. The sugar contained in the pulp of the fruit, as it were, masks the sensation of sour taste, and tannins, on the contrary, emphasize it. So, in the fruits of dogwood there are 9% sugar, but they seem very sour and tart, since they contain a relatively large amount of malic acid and tannins.

Acids play a significant role in canning or culinary processing of fruits. Thus, the amount of acids in the raw material affects the sterilization regime: the higher the acidity of the raw material, the faster the microorganisms die in it when the canned food is heated.