Fresh fruits and vegetables, as well as food products obtained from their processing, are extremely important in the nutrition of people. They are a source of biologically valuable and vital compounds: minerals, essential amino acids, enzymes, vitamins, phytoncides. Many of their types can be stored for a long time without losing their nutritional value. Being everyday products of the diet, fruits and vegetables contribute to a more complete absorption of meat and dairy products, increase the human body’s resistance to colds, promote longevity. With the help of fruits and vegetables, heart and stomach diseases are treated, as well as diseases associated with metabolic disorders in the body. Most baby foods are made from fruits and vegetables. Average annual consumption rates are (in kg): fruits - about 100; vegetables - 126; potatoes - 100-115.

Considerable attention is paid to increasing the production of fruits and vegetables, which will be achieved through the implementation of a set of organizational and economic measures, which will allow by 1990 to increase the production of fruits in the country to 15 million tons, vegetables - to 41, potatoes - to 90-92 million. T.

Chemical composition of fruits and vegetables

The chemical composition of vegetables and fruits determines the most important indicators of their quality: appearance, taste, aroma, keeping quality, as well as nutritional value and calorie content. It is formed under the influence of soil and climatic conditions, varietal characteristics fruit and vegetable products and agricultural cultivation technology. The chemical composition changes as fruits and vegetables grow and form, achieving an optimal combination of individual chemicals during the ripening period.

Water is the main component of vegetables and fruits. Its fruits contain from 72 to 90%, and vegetables and potatoes - from 65 to 96%. Organic and mineral substances are dissolved in it. During storage, fruits and vegetables lose water. This can have the most adverse effect on snoring, as the wilted tissues of fruits and vegetables lose marketable condition, are affected by diseases. Therefore, when storing fruits and vegetables, it is necessary to observe conditions that prevent moisture loss.

Sakharov fruits and vegetables contain no the same number. In fruits it varies from 0.5 (in lemons) to 25% and higher (in grapes). There are significantly fewer of them in vegetables - from 0.2 to 10-12%. Monosaccharides - glucose and fructose - predominate quantitatively in pome fruits. For this reason, apple juice, even with medium sugar content, seems sweet. Stone fruits, on the contrary, are richer in sucrose. Berries contain approximately the same amount of glucose and fructose - 3-4% each, and less than 1% sucrose. In vegetables, the total content of soluble sugars varies within the following limits (in%): in onions - 3.5-12.2; in carrots - 3.3-12; in beets - 5.3-9.2; in cabbage - 1.5-4.5.

From monosaccharides Fruits and vegetables contain glucose and fructose. From disaccharides- sucrose and trihalose (in mushrooms). Among polysaccharides starch, hemicellulose, cellulose, pentosans predominate, also include pectin substances.

Starch is the most important storage carbohydrate. The largest amount of starch is found in potatoes (12-25 %) and in unripe banana fruits (18-20 %). He is also in unripe apples, pears, tomatoes. As fruits ripen, starch is hydrolyzed into soluble sugars. Its hydrolysis also occurs in potato tubers if storage conditions are violated.

Pectic substances in fruits and vegetables they are represented by pectin, pectic acid and protopectin.

Pectin soluble in water; in the presence of sugars and organic acids, it forms jelly, which is widely used in the manufacture of jams, jams, and marmalade.

Pectic acid- a chemical compound less complex in structure, soluble in water.

Protopectin chemically it is the most complex among pectin substances. During storage of fruits and vegetables, it gradually hydrolyzes to form fiber and pectin.

Protopectin usually fills the intercellular spaces, connecting individual cells of the fruit pulp with each other. As a result of its hydrolysis, the cells are separated from each other and the pulp of fruits and vegetables softens. When storing fruits and vegetables, the content of pectin substances in them gradually decreases. The conversion of protopectin into pectin can be slowed down by storing fruits at low temperatures (close to 0°C).

Nitrogenous substances found in fruits and vegetables small quantities and are represented mainly by amino acids and proteins. Among vegetables, the richest in proteins are green peas (up to 5%), as well as potatoes (up to 2%) and root vegetables - beets and carrots, and fruit crops- olives and nuts. In fruits and vegetables, proteins are mainly included in enzymes that regulate metabolism during storage of these products. Daily consumption of potatoes in the amount of 300-400 G Satisfies approximately 30% of human protein needs.

Organic acids in combination with sugars determine the taste of fruits and most vegetables. Typically, each type of fruit contains not one, but several organic acids, with one of them predominant. Thus, in apples, pears and stone fruits, malic acid predominates, in citrus fruits - citric acid. Most vegetables (except sorrel) contain a lot of malic acid. Some acids (benzoic, salicylic, etc.) have bactericidal (antiseptic) properties, protecting fruits and vegetables from diseases. Organic acids oxidize faster during storage of fruits and vegetables than sugars during respiration. As a result, the fruits become tasteless or too sweet.

Vitamins also found in fruits and vegetables. There are water-soluble and fat-soluble vitamins. Water-soluble ones are found only in products plant origin.

Among the water-soluble vitamins, vital is vitamin C(ascorbic acid). Fruits and vegetables are rich in vitamins Group B(B, B L >, B:i, Bg, Bis), which are part of enzymes as an active group and play an extremely important role in regulating metabolic processes in the human body.

Vitamin U (anti-ulcer factor) found in greatest quantities in cabbage vegetables.

Fruits and vegetables are rich carotene(provitamin A). In the body of humans and animals, it turns into vitamin A. Carrots, sweet peppers, parsley, sorrel, melons are rich in carotene, and fruits include sea buckthorn, apricots, and peaches.

Minerals Fruits and vegetables are the main source of minerals for humans. They are concentrated mainly in cell sap. Based on their quantitative content, they are divided into two groups: macro- and microelements.

TO macronutrients include: K, Ca, P, Na, Mg, CI, S, Fe; To microelements- Pb, Cu, Zn, Mo, J, Co, Mn, etc. Macro- and microelements are part of enzymes that regulate water and salt metabolism in the human body. In fruits and vegetables, minerals are in a form that is easily digestible for the body, and their total content ranges from 0.2 to 1.5%. Vegetables are richest in potassium, calcium, phosphorus, sodium, and iron.

Lipids and fats in fruits and vegetables they are contained in negligible quantities and are concentrated mainly in the seeds and skin of the fruit. Skin lipids protect fruits from moisture loss.

Glycosides- these are complex organic compounds that often perform protective functions. In fruits and vegetables they are concentrated in the skin and seeds. Many glycosides have a bitter or pungent taste and a specific odor. Most of them are poisonous to humans. The most common glycosides are:

amygdalin- in the seeds of bitter almonds, apricots, peaches, cherries, plums;

solanine- in the skin of potato tubers, unripe fruits of tomatoes and peppers;

capsaicin- in hot pepper;

limonin And naringin- in the peel and subcutaneous layer of citrus fruits;

sinigrin- in horseradish and mustard seeds.

Fruits and vegetables also contain coloring substances that determine their color and, consequently, their presentation. By chemical nature, most dyes are phenol derivatives.

The composition of fruits and vegetables includes a variety of organic and inorganic substances - water, minerals, carbohydrates, organic acids, vitamins, enzymes, nitrogenous, tannins, pectin substances and others.

Water

Fresh fruits and vegetables contain 72-95% water, with the exception of nuts (5-8%). Due to their high water content, fresh fruits and vegetables have low calorie content, but at the same time have high biological value, since substances dissolved in water are well absorbed by the body. High water content determines the juiciness and freshness of fruits and vegetables. In addition, water is the medium in which the main biochemical processes characteristic of fruits and vegetables take place. Water itself is directly involved in some biochemical processes. With a loss of 5...7% of water, many fruits and vegetables wither, lose their freshness and presentation. Some vegetables (leafy) wilt when they lose 2...3% of water.

Solids

Dry substances are divided into insoluble and water-soluble.

Insoluble substances include cellulose and its accompanying hemicellulose and protopectin, water-insoluble nitrogen compounds, starch, and fat-soluble pigments. . All these substances determine mainly the mechanical strength of tissues, their consistency, and sometimes the color of the skin. The content of insoluble solids in vegetables and fruits is low, on average 2...5%. The amount of soluble solids in vegetables and fruits ranges from 5 to 18%. These include soluble carbohydrates, nitrogenous substances, acids, tannins and other phenolic substances, soluble forms of pectins and vitamins, enzymes, and mineral salts. Most of this group of compounds is represented by carbohydrates - mainly sugars.

The importance of fruits and vegetables is determined not only by the presence of sugars in them, since they are valued not for their calorie content and nutrients, but for their highly aromatic properties, the presence of vitamins, minerals And other substances that are either not found in other food products, or are significantly less than in vegetables and fruits.

Carbohydrates

Carbohydrates in fruits and vegetables are quite diverse both in their physical and chemical properties and in their importance for humans. The most common types of carbohydrates are sugars, starch, inulin, fiber and pectin.

The amount of carbohydrates in fresh fruits and vegetables varies depending on the soil and climatic conditions of their cultivation, agricultural practices, frequency of watering, conditions and timing of harvesting, degree of ripeness, conditions of transportation, storage, etc. For example, in potatoes, when stored at low temperatures (0 ° C), the sugar content increases (sometimes up to 6%) and the amount of starch decreases; in apples, during the process of ripening on the tree, first there is an increase in the amount of starch, and then during the ripening period there is an increase in sugar.

Sugars are carbohydrates most common in fruits and vegetables. Distinguish monosaccharides(glucose, fructose) and disaccharides(sucrose).

Glucose, or grape sugar, is found freely in fruits and vegetables. Fructose, or fruit sugar, of all sugars the sweetest in taste, dissolves well in water. Residues of glucose and fructose molecules form one molecule of sucrose.

Of the disaccharides in fruits and vegetables, the most common is sucrose, the main sugar found in the roots of sugar beets and sugar cane stalks. Sucrose, or beet sugar, is contained in sugar beets (12-24%), sugar cane(14-26%), apples (2-6%) and other fruits and vegetables: dissolves well in water and, under the influence of the enzyme sucrase or acids, is broken down to form equal amounts of glucose and fructose, i.e. invert sugar.

Polysaccharides presented in juicy products starch, inulin, cellulose (fiber), hemicellulose, lignin, pectin substances.

Starch found in potatoes, vegetables and fruits in the form of small grains of various shapes and sizes, visible under a microscope. It is found in significant quantities in potatoes (15-25%), sweet potatoes (up to 20%), green peas (up to 6%), and sweet corn (up to 10%). In ripe fruits, with some exceptions (nuts up to 3.5%, bananas up to 2%), starch is practically absent, since as the fruit ripens and is stored, the starch undergoes enzymatic saccharification and is gradually hydrolyzed. In beans, green peas, and beans, the amount of starch can increase to several percent, especially sharply when they are overripe. At the same time, the amount of sugars is reduced, the product becomes coarser, and its taste deteriorates. By the rate at which starch decreases, one can judge the ripening of apples: in unripe fruits of winter varieties of apples and pears there may be 4-5% of it, and at full maturity - less than 1%. The culinary properties of potatoes are largely determined by the starch content in it: the more starch there is, the better the boilability of the tubers.

Inulin is a substance close to starch, consisting of remnants of fructose molecules, soluble in water; in earthen pear (jerusalem artichoke) it is 11-13% and chicory roots - up to 17%. Starch and inulin play the role of reserve substances in plant tissue.

Fiber (cellulose) found in vegetables in amounts from 0.2 to 2.8%, fruits - from 0.5 to 2.0%. It is insoluble in water, organic solvents, weak acids and alkalis. Fiber is not absorbed by the human body, but it enhances intestinal motility and thereby promotes better absorption of food. The increased cellulose content is associated with the mechanical strength of fabrics, transportability and keeping quality of fruits and vegetables.

Hemicellulose (or semi-fiber) participates in the construction of tissues along with fiber and are reserve substances for fruits and vegetables. Vegetables and fruits contain from 0.2 to 3% hemicelluloses. The total hemicellulose content in vegetables and fruits, as a rule, is higher, the more fiber they contain.

Pectin substances, related to high-molecular compounds, are found in vegetables and fruits in the range from 0.8 to 2.5%. They are found in apples (0.82-1.3%), plums (0.96-1.14%), black currants (0.5-1.52%), cranberries (0.5-1.3%). ), apricots (1.03%), carrots (2.5%), rhubarb (0.8-2.0%) and other fruits and vegetables. In the pectin complex, pectin and protopectin are distinguished. Protopectin is found in intercellular spaces and in cell walls, is insoluble in water and determines the hardness of unripe fruits and vegetables. Pectin is a breakdown product of protopectin and makes up the bulk of pectin substances contained in ripe fruits and vegetables. It dissolves into cold water and is part of the cell juice of fruits and vegetables. Pectin has the ability to form jelly in the presence of sugar and acid, due to which it is widely used in the production of marmalade, jam, fruit caramel fillings, marshmallows, etc.

Nitrogenous substances

These include proteins, amino acids, amides, nitrates, nitrites and other nitrogen-containing substances. Most fruits contain up to 1% nitrogenous substances and only some (grapes, apricots, cherries, raspberries, currants, pomegranates, bananas) - up to 1.5%; the exceptions are nuts (18-20%), olives (6%), dates (up to 3%). Vegetables usually contain more nitrogenous substances than fruits: legumes - 4.5-5.5%, spinach - 2.7-3.7%, cabbage - 2.5-4.5%, garlic - 6, 5%, potatoes, carrots, onions - 1.5-2%, pumpkin and tomato - 0.5-1.3%. Most of the nitrogenous substances in fruits and vegetables are proteins. The proteins of many plant products cannot be considered complete in terms of amino acid composition. During storage and processing of fruits and vegetables, the complex of nitrogenous substances undergoes significant changes.

A special group of nitrogenous substances of protein nature that regulate metabolism in living cells are enzymes. They play an important role in the processes occurring during storage and processing of products, and often determine its quality.

Enzymes. Vegetables and fruits contain special protein substances that are involved in all biological processes occurring in the body. These substances are called enzymes or enzymes. Respiration and ripening of fruits and vegetables, seed germination are enzymatic processes. In some cases, enzymes can play a negative role, for example, under the influence of enzymes, overripening and loosening of tissues, souring of wine, and spoilage of canned food occur. Each enzyme acts only on a specific substance or group of substances. This property of enzymes is called specificity of action. All enzymes exhibit their activity even in low concentrations. The high activity of each enzyme manifests itself under certain environmental conditions. For most enzymes, the optimal temperature ranges from 20 to 50 °C; at a temperature of 60-70 °C, enzymes are inactivated. When products are cooled to 0 °C, the activity of enzymatic processes is greatly reduced, so fruits and vegetables are stored at temperatures close to 0 °C.

Waxes and fats- these are compounds covering the surface of fruits and leaves. They perform a protective role: they protect plant organs from moisture evaporation, the introduction of pathogenic organisms, and the penetration of excessive amounts of water.

Waxes are fat-like substances; they cover the skin of apples, grapes, cabbage leaves and other organs of juicy produce. All waxes are chemically stable and poorly soluble. They dissolve in alkalis when heated. This is taken into account when preparing for drying plums and grapes. A product processed in hot alkali dries faster, as the integrity of the waxy coating is disrupted, cracks form on the skin, the so-called mesh, due to which moisture evaporates faster.

There are very few fats in fruits and vegetables; they mainly accompany the waxes covering the surface. Fats are present in significant quantities in seeds, for example in stone fruits and melons. Therefore, the seeds of such crops are used to obtain oils. Of particular interest is sea buckthorn oil. In sea buckthorn fruits it is from 2.5 to 8%, in seeds - from 10 to 12%. The pulp of other fruits and vegetables contains up to 1% fat, and the seeds range from 4 to 51%. Rich in fat are nuts (50-68%), apricot kernels (30-58%), olive pulp (up to 55%).

Organic acids

Taste properties fruits, some vegetables and their processed products are largely determined by the ratio of sugars and organic acids, which they contain both in free form and in the form of salts. Acids have a significant impact on the degree of sweetness of fruits and vegetables, which is expressed as the ratio of the total amount of sugar to the total amount of acids. Most vegetables, with the exception of tomatoes, sorrel and rhubarb, contain less organic acids than fruits. Some fruits contain up to 2.5% acids (cherries, dogwoods), black currants - up to 3.5%, lemons - up to 8%. The most common acids found in vegetables and fruits are malic, citric and tartaric acids, less commonly oxalic, benzoic, formic, succinic, and salicylic acids.

Apple acid found in almost all fruits. It predominates in pome and stone fruits. It is highly soluble in water, harmless to the human body, and is widely used in the production of sweet waters and confectionery products. There is a lot of it in garden rowan (up to 2.2%), chokeberry (up to 1.3%), dogwood (up to 2%) and sea buckthorn (up to 2%), as well as in rhubarb (up to 1%), tomatoes (up to 0.5%). The taste is slightly acidic.

Lemon acid usually found in fruits along with malic and sometimes tartaric acids. Contained mainly in citrus fruits (lemon - up to 6%, other citrus fruits 1...2%) and cranberries (3%). The taste is mildly sour.

Wine acid found in grapes (0.3-1.7%), where it is in the form of an acidic potassium salt called cream of tartar, as well as in a small amount in a free state. In other fruits and berries there is either little of it (gooseberries, lingonberries, strawberries, cherries, plums), or it is completely absent.

Benzoic acid found in cranberries (up to 0.01%) and lingonberries. Free benzoic acid is an antiseptic, and therefore lingonberries and cranberries are well preserved in fresh.

Oxalic acid found in many fruits and vegetables, but in small quantities. There is a lot of it in sorrel (up to 0.7%) and rhubarb (up to 0.2%), spinach (up to 0.2%), soda strawberries (up to 0.01%), blueberries (0.06%) where it is contained mostly in the form of potassium oxalate. Oxalic acid, being a strong acid, even in small concentrations in solutions irritates the mucous membranes in the human body.

succinic acid found in very small quantities in unripe cherries (absent in ripe ones), red currants, gooseberries, grapes, apples, cherries. Succinic acid, even in the form of a 3% solution, does not irritate the gastric mucosa, but has an unpleasant taste.

Salicylic acid found in strawberries (0.0001%) and raspberries (0.00011%), has antipyretic properties. Cultivated varieties of these berries contain more salicylic acid than wild ones.

The composition of fruit and vegetable products also includes caffeic, quinic and chlorogenic acids in small quantities.

Vitamins

Fruits and vegetables, especially when consumed fresh, are an important source of vitamins, and in relation to vitamins C, P, folic acid (vitamin B 9) they are the only source, which gives grounds to consider fruits and vegetables a necessary and irreplaceable part of the human diet .

Vitamins are divided into water-soluble and fat-soluble.

Water-soluble vitamins. Vitamin B 1 (thiamine) is found in small quantities in vegetables and fruits (0.01-0.34 mg per 100 g), heat treatment causes slight destruction of this vitamin.

Vitamin B 2 (riboflavin) mainly enters the human body with products of animal origin. In fruit and vegetable products, this vitamin is found in pears (0.05 mg per 100 g), peaches (0.02 mg per 100 g), tomatoes (0.04 mg per 100 g), carrots (0.02-0.07 mg per 100 g), beets (0.04 mg per 100 g) and other fruits and vegetables. Riboflavin is very sensitive to the effects ultraviolet rays Therefore, products should be stored away from direct sunlight.

The main sources of vitamin C (ascorbic acid) are vegetables, fruits and berries. The richest in this vitamin are fresh rose hips (up to 650 mg per 100 g, dried up to 2000 mg per 100 g), sweet peppers (green 150 mg per 100 g, red 250 mg per 100 g), black currants (250 mg per 100 g) , sea buckthorn (60 mg per 100 g), lemon (40 mg per 100 g), parsley (150 mg per 100 g), dill (100 mg per 100 g), etc. The content of vitamin C in food products has a significant impact the duration of their storage and type of culinary processing. At in various ways Sterilization of fruits and vegetables destroys a significant amount of vitamin C, especially in the presence of oxygen and in light. This destruction is facilitated by the presence of metals. For this reason, metal and unvarnished containers should not be used when canning. The loss of vitamin during drying is especially high – up to 70%. The vitamin is better preserved by rapid freezing and subsequent storage of fruits, vegetables and berries at sub-zero temperatures. In such products, up to 90% of the original vitamin C content is retained.

Fat-soluble vitamins. Plants contain provitamin A (retinol) - the pigment carotene. Rich in carotene are carrots 8 mg per 100 g, apricots and peaches 1.7...9.0 mg per 100 g, pumpkin (1.5 mg per 100 g), fresh rose hips (2.6 mg per 100 g), parsley (5 .7 mg per 100 g), dill (1.0 mg per 100 g). Carotene is quite heat-resistant and is well preserved when canning foods.

Vitamin D (calciferol) refers to several compounds that are similar in chemical structure (vitamins D2, D3). Fruits and vegetables contain very little vitamin D, but their provitamins - sterols or sterols - are present.

Vitamin E (tocopherol) is a group of seven vitamins. An important source of vitamin E are vegetable oils, sea buckthorn, lettuce and other green and cabbage vegetables. Tocopherols are highly stable and do not degrade when heated or exposed to ultraviolet rays.

There are other essential organic substances that come from food and have specific biological effects. These substances include vitamin K, vitamin P, vitamin F. Currently, they are commonly called vitamin-like substances.

Minerals

The amount of mineral substances is determined by the content of ash remaining after burning a sample of raw materials. Most fruits and vegetables have an ash content of 0.25 to 2.50%. A specific feature of the mineral substances of fruits and vegetables is an alkaline reaction, while the mineral substances of grains and animal foods are acidic.

Vegetables and fruits contain from 0.5 to 2% minerals. All of them are divided into macroelements - potassium, calcium, sodium, magnesium, phosphorus, sulfur, chlorine; trace elements - iron, iodine, fluorine, chromium, bromine, manganese, zinc, nickel, cobalt, selenium, copper, etc.; ultramicroelements - gold, lead, mercury, silver, radium, ruby. Macroelements are contained in relatively large quantities, measured in fractions of a percent or milligrams per 100 g of product.

Fruit and vegetable products contain potassium salts (pumpkin, zucchini, watermelon, apple), cobalt (beets, strawberries, red currants), iodine (feijoa), iron (green and cabbage vegetables (0.6...1.4 mg per 100 g), tomatoes (0.9 mg per 100 g), strawberries (1.2 mg per 100 g).

Lignin and cutin

Lignin and cutin are very common in plants. Lignin is a complex substance that permeates cell walls and promotes their lignification. Sometimes lignin accumulates in the pulp of fruits and vegetables, making it rough, for example in woody root vegetables, stony granulations of the pulp of some pears and quinces. Cutin refers to the waxy substances that coat the surface of fruits and vegetables. This waxy coating protects them from withering, from the action of microorganisms and from wetting with water.

Tannins

Tannins are found very often in vegetables and fruits, but in small quantities. Sloes, cherry plums and persimmons are rich in these substances, in which their content reaches 2%; there are a lot of tannins in quince, dogwood and rowan (up to 0.6%). However, despite the insignificant content, tannins impart an astringent taste to fruits (especially when the content is above 0.5%). Unripe fruits usually contain more tannins, but as the fruit ripens, the amount decreases as they are used up in respiration along with sugars and acids. Under the action of enzymes in the presence of oxygen, tannins are easily oxidized, and dark-colored compounds are formed - phlobaphenes. This reaction explains the darkening of the pulp of apples, pears, quinces and other fruits, as well as potatoes when cut.

Glycosides

Glycosides are contained in vegetables and fruits in very small quantities, for example in potatoes from 0.002 to 0.1%. They are harmless in small doses, but dangerous in large quantities. Many glycosides give fruits and vegetables a bitter taste or specific aroma. Glycosides can be localized in the skin, pulp or seeds of fruits and vegetables. The most common glycosides found in vegetables and fruits are:

Amygdalin is a glycoside found in the seeds of stone fruits and pome fruits.

· vaccinin - a glycoside contained in lingonberries and cranberries, together with benzoic acid, determines the high resistance of these berries to the action of microorganisms: lingonberry and cranberry juice do not ferment.

· hesperidin Found in the peel of citrus fruits, it has the properties of vitamin P.

· solanines found in potatoes, eggplants, and tomatoes. In potatoes they are found mainly in the skin and outer layers, which are removed during peeling.

· sinigrin found in horseradish and black mustard seeds. White mustard seeds contain glucoside sinalbin.

Among other glucosides, it should be noted gluconasturcin, found in turnips, as well as capsaicin, giving burning taste pepper.

Dyes

Coloring agents (pigments) give fruits and vegetables various types and varieties of one color or another. By color, you can determine the ripeness of fruits and some vegetables, for example, the color of tomatoes changes from green to red as they ripen, the color of apples - from green to yellow in different shades. There are several groups of plant pigments.

Chlorophyll- a green plant pigment that gives many fruits and vegetables their green color; plays a large role in the process of assimilation of carbon dioxide from the air by green plants under the influence of sunlight. This process is called photosynthesis.

Carotenoids- a group of pigments that give fruits and vegetables their orange, yellow, and sometimes red color. Carotenoids include: carotene, lycopene, xanthophyll, etc.

Carotene gives orange color to carrots and apricots; found in tomatoes, peaches, citrus fruits, as well as green vegetables, but the color of carotene in it is masked by chlorophyll.

Lycopene is an isomer of carotene; it causes the red color of ripe tomatoes, but does not have vitamin activity.

Xanthophyll is a yellow pigment, but lighter than carotene. Xanthophyll, together with chlorophyll and carotene, is found in green vegetables and, together with carotene and lycopene, in tomatoes.

Anthocyanins- these are coloring substances that give fruits, vegetables, and flower petals a wide variety of colors - from pink to black-violet. They are found either in the skin of fruits (grapes), or in the skin and pulp at the same time (raspberries, blueberries, currants, some varieties of grapes, beets, etc.). The most common anthocyanins in vegetables and fruits are: enine (red-brown) (grapes), idein (lingonberries), keracyanin (cherries), betaine (beets). Anthocyanins are highly soluble in water; when heated for a long time they are destroyed. The accumulation of anthocyanins in fruits can serve as one of the signs of ripeness.

Flavones and flavonols- substances that provide yellow color to fruits and vegetables are found in the form of glycosides. Flavonols include apigenin, which is found in parsley and orange fruits. Flavonols include, for example, quercetin, the coloring substance in dry onion scales.

Essential oils

Fat-soluble volatile substances that impart flavor to fruits and vegetables. The content of essential oils increases as the plant fruits grow and ripen. Many fruits and vegetables, including citrus fruits (lemons, tangerines) and spicy vegetables(onion, garlic, radish, celery, parsley, dill, horseradish, etc.) contain a significant amount of essential oils. Essential oils spice plants not only determine the specific taste and aroma of salted, fermented and pickled products, but also prevent the development of rotting processes during lactic fermentation, as well as during pickling.

The richest in essential oils are citrus fruits (from 1.2 to 2.%), spicy vegetables (parsley, celery, dill - on average 0.05-0.%), as well as garlic (0.01%) and horseradish ( 0.0%).

Phytoncides

The name itself means, firstly, that these are substances of plant origin, and secondly, that they have properties that are destructive to other organisms. Many plants have phytoncidal properties. Some plants release into the environment a large amount of volatile substances that are toxic to many microorganisms, while others release an insignificant amount of phytoncides, but often their tissue juices have very strong bactericidal properties. Onions and garlic have the greatest phytoncidal properties. However, many microorganisms have adapted to the phytoncidal environment and therefore can cause plant diseases.

Chemical composition and nutritional value of vegetables

The chemical composition of vegetables includes organic and inorganic compounds, the quantitative and qualitative ratio of which determines their nutritional value.

Selecting a variety of vegetables and fruits in your daily diet helps improve metabolism and affects human health. The proper development and growth of children largely depend on providing their body with substances contained almost exclusively in fruits and vegetables. In older people, due to deteriorating metabolism, vegetables and fruits act as a kind of metabolic stimulant.

With the systematic consumption of fruits and vegetables, you can regulate the intake of vitamins, minerals and other biologically active substances into the body, thereby improving your condition or even curing yourself from one or another disease.

The lack of vegetables in the diet during expeditions to the North and long journeys has long led to metabolic disorders in the human body, which manifested itself in the form of scurvy, polyneuritis, anemia and other diseases.

The high water content determines the low energy value of vegetables compared to other products (with the exception of potatoes rich in starch), while the concentration of biologically active substances in vegetables - vitamins, microelements, antimicrobial substances, radiation-protective antiradiants, phenolic and other compounds - distinguishes vegetables as the most important food group products necessary for daily nutrition. The absence or deficiency of these substances leads to frequent illnesses, fatigue, lethargy and increased sensitivity to cold, weakened vision and other disorders in the human body. On the contrary, the presence of vegetables in the diet improves appetite, increases the secretion of gastric juice, which promotes better digestion of food.

Vegetables, along with fruits, are considered primarily as a source of vitamins. The science of biologically valuable vegetables has become widespread in everyday life. Today, every housewife and mother knows that carrots are rich in provitamin A - carotene, but not everyone knows that this vitamin is absorbed almost completely only when the product is consumed with fats.

The selection of vegetable crops is currently directed by scientists not only to the development of new varieties that are distinguished by good taste qualities, high yield and frost resistance, but also a high content of vitamins and other bioactive substances.

The processing industry is faced with the task of identifying better methods of canning and creating “softer” technological modes, allowing you to preserve the most biologically valuable substances and reduce waste during industrial processing of raw materials.

Medicine sets the task not to treat, but to prevent diseases by recommending food rations that include vegetables, fruits and berries rich in medicinal properties.

Special studies have long established that therapeutic effect natural biologically active substances of fruits and vegetables are significantly higher than prepared ones medical supplies. Thus, garlic contains essential oils that can kill influenza viruses, and is used by the population as a prophylactic against the disease. Vitamin C is absorbed better in the presence of P-vitamin substances, which are concentrated mainly in fruits and vegetables.

Let's look at the chemical composition of vegetables more specifically.

Water makes up on average about 85-87% of the weight of vegetables. Normal water content ensures the juiciness of vegetables; evaporation of moisture leads to their withering, deterioration in appearance and consistency. Water in vegetables is mainly in a free state in the form of cell sap, in which valuable nutrients are dissolved; only 5% of water is associated with proteins and other substances.

Water is a medium in which various hydrolytic processes take place intensively, playing an important role in the life of vegetables and maintaining their commercial quality. At the same time, it should be noted that increased water content reduces their energy value (calorie content) and the percentage of finished product yield when processing vegetables.

Water is favorable soil for the development of microorganisms. Early varieties of vegetables, characterized by a higher water content compared to late varieties, are more easily susceptible to microbiological and physiological diseases and to long-term storage not suitable.

Carbohydrates make up about 80% of the total dry matter contained in vegetables. Potatoes contain a lot of starch (18% on average); other vegetables (with the exception of legumes) are dominated by easily digestible sugars: sucrose, glucose and fructose. Their content can vary widely: from 1.5-2.5% in potatoes, cucumbers, lettuce and spinach to 6-9.5% in carrots, beets, watermelons and melons.

Along with fiber, the skins of vegetables contain semi-fiber or hemicellulose, which is a combination of cellulose and sugars. During the hydrolysis of semi-fiber, free sugars are formed, which can be involved in respiration processes as reserve material for the plant. However, the more hemicellulose, the coarser the consistency, the lower the digestibility, but the better the shelf life, since along with fiber, these substances provide the mechanical strength of vegetables. The content of semi-fiber is within the same limits as fiber - from 0.5 to 2%.

Glycosides. These are complex compounds of Sugars (glucose, rhamnose, galactose, etc.) with various non-carbohydrate substances: acids, alcohols, nitrogenous, sulfurous and other compounds.

Glycosides give vegetables a specific taste, sometimes astringent, sour or bitter. The glycoside solanine can accumulate in green potatoes during the germination of tubers, root vegetables and other vegetables. The solanine content in green potatoes up to 0.02% causes severe poisoning Therefore, the presence of greened tubers in a batch of potatoes is strictly regulated (no more than 2%). Tubers with greening of more than one quarter of the surface are classified as waste.

Glycosides play the role of reserve substances in the life of vegetables; the sugars formed during their hydrolysis are involved in respiration processes. Many glycosides have an antimicrobial, that is, bactericidal effect, inhibiting the development of bacteria and fungi. The bitterness of many vegetables, due to the content of glycosides, is considered as a protective agent of the plant from being eaten by birds and other animals. Thus, the hot taste of pepper is created by the glycoside capsaicin, and that of horseradish and mustard by sinigrin.

Pectic substances. By their chemical nature, pectin substances are close to carbohydrates and are high-molecular compounds. They enter the median plates and cell walls, and in a dissolved state - into the cell juice of vegetables. This group of compounds includes protopectin, pectin, pectic and pectic acids.

Protopectin consists of pectin and cellulose. According to some researchers, it contains araban hemicellulose, which contains arabinose sugar. Protopectin is insoluble in water and causes the toughness of unripe vegetables. When ripened, protopectin breaks down to release free pectin, easily soluble in water, while the consistency changes from hard to soft, characteristic of mature vegetables; these changes, for example, are easily observed during the ripening of tomatoes.

Pectin is a polygalacturonic acid, the carboxyl groups of which are saturated with residues methyl alcohol. Hydrolysis of pectin usually occurs at the stage of overripening and aging of vegetables as a result of the detachment of methoxy groups and the rupture of the polygalacturonic chain of the molecule. In this case, pectic acid is formed first, then pectic acid. The cellular structure of vegetables is destroyed, they acquire a flabby consistency and are quickly affected by diseases.

Modern ideas about the role of pectin substances have undergone significant changes. Research has shown that they are very important for maintaining the normal physiological state of vegetables. The destruction of the structure of protopectin and pectin is directly dependent on the quality and shelf life of vegetables.

For the human body, from ballast (indigestible substances), as previously thought, they have turned into substances that play the role of antitoxicants and antiradiants. Pectin substances, by binding salts of heavy metals (lead, nickel, etc.), detoxify the body. Their role is especially important as protective antiradiants that remove radioactive isotopes of strontium, radium, etc. from the body.

In current conditions, the presence of radiation-protective antiradiants in food, which are the pectin substances of vegetables, is especially important.

Organic acids. They have great taste value, increasing the digestibility of both the vegetables themselves and the rest of the food when consumed together. They play a protective role against microbiological diseases of the vegetables themselves. Organic acids, as more oxidized substances, are easily involved in respiration processes and, along with sugars, are the most important substrate of the plant cell. This is why the sour taste of vegetables decreases during storage: this is especially noticeable in fruits and berries.

Many organic acids are volatile, create the aroma of vegetables, and have phytoncidal, that is, antimicrobial properties. In vegetables, malic acid and oxalic acid (in sorrel) predominate. The total acid content in vegetables ranges from 0.1-2%.

The intensity of the sour taste depends on the concentration of free hydrogen ions, indicated by the pH sign. In a neutral environment the pH is 7, in an acidic environment it is below 7, in an alkaline environment it is higher. In vegetables, the pH is less than 7, that is, an acidic environment predominates.

The sour taste can be neutralized by sugars, and enhanced by the presence of tannins (astringents). The pH value for many canned foods is regulated, since increased acidity indicates signs of product spoilage.

Tannins. They are a variety of phenolic compounds that give vegetables their tart, astringent flavor; they are mainly contained in unripe vegetables. As vegetables ripen, the tannin content decreases. These plant compounds are called tannins because of their ability to tan leather.

Phenolic compounds play an important role in the respiration processes and immunity of potatoes and vegetables against microbiological diseases and have antimicrobial properties.

Research has established a direct connection between the accumulation of phenolic compounds and the resistance of certain varieties of potatoes and vegetables against microbiological diseases.

For the human body, some phenolic compounds are very important due to their P-vitamin activity (catechins, tannins, etc.).

Under the influence of atmospheric oxygen, phenolic compounds are easily oxidized to form dark-colored substances - phlobaphenes.

These processes are undesirable, especially when drying and canning vegetables, since the appearance finished products getting worse. To prevent cut vegetables from darkening during processing, they are blanched, that is, treated with steam or boiling water. In this case, oxidative enzymes are destroyed; in addition to the natural color, vitamins are better preserved in vegetables. The total content of phenolic compounds varies widely - from hundredths to 1-2%.

Dyes. The diverse colors of vegetables are created mainly by four groups of organic compounds: chlorophyll, carotenoids, anthocyanins and flavones.

Chlorophyll, a green pigment involved in plant photosynthesis, is an ester of chlorophyllic acid with two alcohols - phytol and menthol. At the center of the complex chlorophyll molecule is a magnesium atom. When magnesium is eliminated, which occurs during cooking vegetables, pheophytin is formed, which gives cooked vegetables first a yellow-brown, then dark brown color. This color change is especially noticeable when green vegetables are cooked for a long time.

As vegetables ripen, the amount of chlorophyll in them decreases, and the amount of carotenoids increases.

Carotenoids give vegetables their yellow to orange-red color. The main representative of this group of pigments is carotene, the properties of which are discussed in the “Vitamins” section. The more double bonds in the carotenoid hydrocarbon chain (7-13), the brighter the color of the vegetables.

Anthocyanins belong to the class of glycosides, consisting of a sugar residue and the pigment anthocyanidin, a substance of phenolic nature. The color of vegetables, depending on the type of pigment and pH of the environment, can be red, blue, purple, with various intermediate shades. Many anthocyanins have P-vitamin activity and antimicrobial properties.

Flavone substances (yellow-orange pigments) comprise a large group of phenolic compounds, but it is mainly flavonols that give color to vegetables. In their chemical nature and properties, flavonols are in many ways similar to anthocyanins.

Leukoanthocyanins are colorless precursors of anthocyanins and flavonols. In structure and properties they are close to tannins and can be formed by their enzymatic oxidation. During hydrolysis with hydrochloric acid and ripening of vegetables, leucoanthocyanins pass from a colorless form to a colored form - anthocyanins.

Aromatics. The smell of vegetables is created by a large and chemically diverse amount of various substances (terpenes, aldehydes, ketones, alcohols, organic acids, esters and others). Spicy vegetables contain many aromatic substances - parsley, parsnips, celery, onions, garlic and others. Common property aromatic substances is their volatility. Released during sublimation, they are also called essential oils. Many of them have a strong bactericidal effect and are considered phytoncides. So, one clove of garlic is enough to sterilize the oral cavity from the influenza virus for a day. That is why consumption of onions and garlic is the most important preventive measure against this type of disease.

Nitrogenous substances. They are found in vegetables in small quantities - from 0.5 to 1-2%, with the exception of legumes (up to 5%), cauliflower (4.5%), garlic (6.5%), spinach (3.5% ). The proteins of these vegetables are very valuable in amino acid composition. In addition to proteins, nitrogenous substances include free amino acids, acid amides, ammonia compounds and others.

However, being in small quantities, proteins play an important role in the life of the vegetables themselves. Protein biosynthesis underlies immunity, that is, the resistance of vegetables against microbiological and physiological diseases. Being able to regulate protein biosynthesis, scientists direct the breeding of new economic and botanical varieties of vegetables with specified properties that determine high yield, frost and drought resistance, immunity to microbiological diseases, and increased nutritional value.

A particularly important role in the life of vegetables is played by peculiar proteins - enzymes that regulate all biochemical processes, which have a significant impact on the quality and shelf life of potatoes and vegetables. Respiration processes and changes in the chemical composition during the ripening and aging of vegetables occur with the participation of various enzymes; their inactivation, that is, destruction, leads to sharp changes in the quality of vegetable products.

Fats. Vegetables contain them in very small quantities. Their total content in the pulp of vegetables is no more than 1%; in melon vegetables - pumpkin, watermelon, melon - the fat is concentrated in the seeds.

Vitamins. All vitamins are usually divided according to their solubility into two groups - water-soluble and fat-soluble. The first group includes vitamins B1, B2, B3, B6, B9 (folic acid), B12, B15, PP, C (ascorbic acid); to the second - A, D, E, K. In addition, a number of substances make up a group of vitamin-like compounds.

Vegetables are especially rich in water-soluble vitamins such as ascorbic acid, as well as in slightly smaller quantities - vitamins P and B 9,% cabbage - vitamin U. B vitamins (with the exception of B 9), as a rule, are found in vegetables in tenths and hundredths fractions of a milligram and a significant role in vitamin balance food is not played.

Of the fat-soluble vitamins, vegetables contain mainly carotene (provitamin A).

Vitamin C was discovered by the Hungarian biochemist Szent-Gyorgyi, who called it ascorbic acid, that is, it acts against the disease scarbut or scurvy.

A characteristic sign of the appearance of scurvy is general weakness of the whole body with a significant decrease in appetite and performance, while the gums of the teeth begin to bleed, pinpoint hemorrhages appear especially noticeably under the skin of the legs, and the activity of the heart, liver, and kidneys deteriorates. Numerous studies have established that vitamin C has a neutralizing effect on various drugs and toxic substances, suppressing their toxicity, and accelerates the healing of wounds and bone fractures.

Ascorbic acid is partially destroyed under the influence of metal equipment during industrial processing, metal utensils, culinary preparation food. Therefore, contact of vegetable products with metal should be minimized. The destruction of vitamins is accelerated by prolonged exposure of the product to high temperatures. But ascorbic acid is well preserved in an acidic environment, so, for example, sauerkraut is an excellent source of this vitamin for a long period.

The preservation of vitamin C in the product is facilitated by the content of sugars, proteins, amino acids, and sulfur compounds, which suppress the activity of the enzyme ascorbic acidase, which has a destructive effect on ascorbic acid.

A lot of vitamin C is contained in sweet red pepper - 250 mg per 100 g of edible part, in green pepper - 150, parsley - 150, dill - 100, spinach - 55, sorrel - 43, white cabbage and kohlrabi - 50, cauliflower - 70, green onions (feather) - 30. The presence of vitamin C in potatoes is relatively small - from 7 to 20 mg%. However, when consuming 300 g of tubers per day, even taking into account the destruction of ascorbic acid during culinary processing by 1/4 of the original content, we obtain 30-40% of the required amount of vitamin from potatoes.

Vitamin P. Like ascorbic acid, vitamin P was first discovered by the scientist Szent-Gyorgyi, who in 1936 isolated crystalline powder from lemon peel and called it citrine. Vitamin P includes a large group of substances of polyphenolic nature, called bioflavonoids. The healing properties of bioflavonoids lie in their ability to normalize the permeability and elasticity of blood capillaries. It is assumed that vitamin P protects the hormone adrenaline from oxidation, on which the integrity of blood capillaries depends. Currently, more than 150 polyphenols with P-vitamin activity are known. By promoting vasodilation, P-vitamin substances also have an anti-inflammatory and anti-allergic effect on the human body. All these substances not only prevent sclerosis of blood vessels, but also lower blood pressure, preventing hemorrhage in the heart muscle and cerebral cortex.

Vitamin P promotes the increased therapeutic effect of ascorbic acid, which is why it is also called vitamin C 2. Their combined use in the prevention and treatment of many infectious, ulcerative and other diseases is more effective than each individually.

Vitamin B 9 is more often mentioned in the literature under the name folic acid. If there is a lack of it in the blood, the amount of hemoglobin sharply decreases and anemia or leukemia appears. A decrease in the percentage of hemoglobin in the blood also slows down its clotting, which leads to internal hemorrhages. It has been established that folic acid promotes better absorption in gastrointestinal tract vitamin B 12.

These vitamins, acting together, ensure normal blood circulation processes. Synergy, that is, joint therapeutic effect folic acid and vitamin P, recommended for the prevention and treatment of radiation sickness, atherosclerosis, liver diseases and obesity.

There is a lot of folic acid in leafy vegetables. At heat treatment vegetables, it is easily destroyed, so greens, as a source of vitamins, are best consumed raw, especially green salads.

Vitamin U. Isolated from white cabbage juice; is an important source of methyl groups used by the body in metabolic processes. It has a therapeutic effect for gastritis and other gastrointestinal diseases.

Along with white cabbage, there is a lot of vitamin U in green vegetables: parsley, dill, onions (feathers), spinach, lettuce; It is also found in other vegetables - potatoes, tomatoes, cucumbers.

Vitamin A is a growth vitamin, especially necessary for children; It is also called axerophthol, which helps prevent the eye disease xerophthalmia. In low light, vision weakens until it is completely lost at dusk, commonly known as “night blindness.” The cornea of ​​the eyes undergoes drying out (xerosis - in Latin “drying”), while the protective functions of the lacrimal glands are disrupted and the eyes are easily affected by pathogens. With a lack of vitamin A, inflammation of the mucous membrane of the respiratory organs also occurs, which increases the risk of pneumonia, tuberculosis, and measles. It has been experimentally established that vitamin A affects the redox processes of respiration, protein and carbohydrate metabolism, and the functions of the endocrine glands.

However, it should be noted that excessive consumption of vitamin A is not advisable, as this can lead to poisoning of the body - hypervitaminosis.

Unlike animal products - meat, milk, which directly contain vitamin A, vegetables contain its provitamin - carotene. Carotene is a pigment that gives vegetables their yellow-orange color.

The richest in carotene (in mg per 100 g of edible part): carrots - 9; spinach - 4.5; sorrel - 2.5; salad - 2.75; green onion (feather) - 2; sweet red pepper - 2; sweet green pepper - 1; parsley - 1.7; pumpkin - 1.5.

Vitamin K (naphthoquinone) promotes normal blood clotting (K comes from the word “coagulation” or clotting).

A deficiency of this vitamin can lead to decreased blood clotting and internal hemorrhage.

In addition, vitamin K has a positive effect in the treatment of liver and intestinal diseases.

Vitamin K is found in a lot in salad-spinach vegetables and other greens, as well as in potatoes and white cabbage.

Microelements. Minerals in vegetables range from 0.5 to 1.5%. Depending on the quantitative content in food products, they are divided into two groups - macro- and microelements. Macroelements include potassium, sodium, phosphorus, sulfur, magnesium, contained in vegetables in tenths and hundredths of a percent. A person also receives these elements in sufficient quantities from bread and other cereals and foods of animal origin, and therefore does not experience a deficiency in their diet. Microelements are contained in vegetables in thousandths and millionths of a percent, but for human body each of them is of the utmost importance.

Research by Academician V.I. Vernadsky on the close relationship between the chemical composition of the organic world and mineral substances environment served as the basis for a comprehensive study of the biological role of trace elements. Back in 1916, the scientist noted that the life of every living organism is closely connected by its structure of the earth's crust.

In total, about 70 chemical elements have been identified in the human body, of which 14 microelements are currently considered essential. These are iron, iodine, copper, zinc, manganese, molybdenum, selenium, chromium, nickel, tin, silicon, fluorine, vanadium, cobalt. Some of them were found in negligible quantities, in the form of traces.

Vegetables, extracting microelements from the deep layers of the soil through the root system, accumulate them in all parts of the plant, being the most important source of these substances in the diet.

Numerous studies by Soviet scientists have established that in the process of blood circulation, iron, cobalt, nickel, copper, manganese and other trace elements are most active.

About 200 enzymes (1/4 of the known species) are activated by metals.

Iron is the most common microelement (the human body contains 4-5 g), regulates the processes of blood circulation, growth, respiration, fat and mineral metabolism, being part of a number of enzymes. There is relatively a lot of iron in spinach, sorrel, parsley, dill, garlic, tomato, carrots, beets, and cauliflower.

Cobalt (the adult human body contains 1.5 g) is part of vitamin B 12, which promotes the synthesis of hemoglobin. Cobalt is found in the liver and kidneys and plays an important role in the processes of growth, carbohydrate and fat metabolism. The presence of cobalt contributes to the accumulation of many vitamins in vegetables.

Nickel is involved in complex biochemical processes occurring in the body, and fluctuations in its content in the blood are their reflection. For example, a decrease in the concentration of nickel in the blood was noted in patients with cardiosclerosis, cirrhosis of the liver, etc. This is a very toxic element (causes damage to lung tissue).

Among vegetables, a noticeable amount of nickel was found in potatoes, white cabbage, carrots, watermelon, garlic, green onions, lettuce, spinach, and dill.

Copper (about 100 mg in the human body) is part of many enzymes that regulate the redox processes of respiration; a hematopoietic element, it has a particularly effective effect together with iron. It has been revealed that many diseases in children are associated with copper deficiency in the body; in adults, deficiency of this element is almost not manifested. A higher than normal dose of copper intake (more than 2 mg per day) is highly toxic.

When canning vegetables, the amount of copper during contact of the product with the equipment may increase, so its content is strictly limited (no more than 5-30 mg per 1 kg of product).

Tomatoes, eggplants, spinach, green peas, and rutabaga are rich in copper, which are recommended in the diet for pernicious anemia.

Zinc (an adult contains about 2.5 g). The biological role is not fully understood, although it is a vital trace element. His role is twofold. On the one hand, life activity is impossible without it, since it is part of hematopoietic and other metalloenzymes, on the other hand, zinc compounds are very toxic (1 g of zinc sulfate causes severe poisoning, so the content of this metal in canned food is strictly regulated).

About 12 mg of manganese is found in the adult human body. It accelerates the formation of chlorophyll in green plants and is part of redox enzymes. The lack of manganese in food causes a decrease in growth and vitality. Contained in all green vegetables, cabbage, potato tubers.

Iodine (the human body contains 10 mg) is distributed in very small doses in soil, river and, especially, sea water.

Disease of the thyroid gland (development of goiter) is associated with a lack of iodine in food. It is involved in the absorption of calcium and phosphorus by the body.

A rich source of iodine is seaweed, as well as beets.

Fluoride (2.6 g in the body of an adult). Increases the strength of the skeleton and tooth enamel. A lack of fluoride causes caries, and an excess causes the acute disease fluorosis (stained tooth enamel).

Phytoncides. The name "phytoncides" consists of two parts: "phyto" - a plant, the particle of the word "cides" means that they are poisonous. “But these are healing poisons of plants,” this is what the founder of the doctrine of phytoncides, Professor of Leningrad University B.P. Tokin, said about them. The fact is that phytoncides have a toxic effect on microorganisms that infect plants and on microflora that are pathogenic to the human body.

Very convincing experiments can be carried out on the phytoncidal effect of fresh onion or garlic: the onion is ground and the resulting pulp is placed next to a drop of liquid in which there are any mobile pathogenic microbes. Within a minute, it is found that the movement of bacteria stops. If after 10 minutes you inoculate these bacteria on a nutrient medium, they will not multiply: they were killed by volatile substances released from onions.

Phytoncides are not one, but many different substances that can have a detrimental effect on microorganisms in subtle doses. But non-volatile substances also have phytoncidal properties, for example, coloring pigments - anthocyanins, flavones, organic acids and other compounds.

Eating raw vegetables rich in phytoncides prevents gastrointestinal diseases.

Phytoncides of vegetable food exert their sterilizing effect in the upper sections respiratory tract, preventing the development of sore throat, bronchitis, etc.

Although the chemical composition of onion phytoncides and... garlic is not yet known exactly, but from garlic bulbs, in particular, the substance alliin has been isolated, which, when diluted 1:250,000, has an inhibitory effect on the development of pathogenic bacteria and is used as a medicinal drug. But alliin is only one of the components of a complex complex of garlic substances, which are phytoncides.

The phytoncidal properties of plants are found wide application V agriculture and storage practices for vegetable products. Both favorable and negative facts of interaction of vegetables with each other have been revealed. For example, planting tomatoes between the rows of gooseberry bushes prevents the latter from being damaged by agricultural pests. Aqueous infusions of onion or garlic scales instantly kill spores of the late blight fungus that attacks potato tubers. Spraying sand with such an extract, used during storage for layering carrots, inhibits the damage to root crops by fungus (white rot). Radish and horseradish have the same antimicrobial effect when placed next to each other.

In addition to onions, spicy vegetables - dill, parsley, parsnips, celery and others rich in essential oils - have a high phytoncidal effect.

Introduction

2. Classification of fresh fruits and vegetables. Characteristics of individual species

3. Transportation and receipt of fresh fruits and vegetables

4. Processes that occur during storage of fresh fruits and vegetables

5. Factors affecting food safety

Conclusion

Bibliography

Introduction

In this work, I examined the chemical composition and nutritional value of fresh fruits and vegetables, their classification and characteristics of individual species. Processes occurring during storage of fresh fruits and vegetables. Factors affecting food safety.

I studied the composition of many fruits and vegetables, as well as the presence in them of such vital vitamins for the human body as:

• Vitamin C
• Vitamin A
• Vitamin B
• Vitamin B1
• Vitamin B2
• Vitamin D
• Vitamin E.

She spoke about the important role of organic acids, minerals, carbohydrates, proteins, and fats.

1. Chemical composition and nutritional value of fresh fruits and vegetables

All fruits and vegetables contain large amounts of water (about 75% - 85%). The exception is nuts, which contain on average only 10% - 15% water. Moisture in fruits and vegetables is found in both free and bound states.

Bound moisture is removed to a lesser extent and is partially retained during drying treatment.

Free moisture is a good breeding ground for putrefactive bacteria and microbes, so fruits and vegetables containing large amounts of free moisture cannot be stored for long and need to be processed. Fruits and vegetables are the main suppliers of carbohydrates. These are mainly monosaccharides (glucose, sucrose), disaccharides (sucrose), polysaccharides (fiber, pectin substances).

Pectin substances and fiber are classified as ballast substances in their properties.

In addition to carbohydrates, the chemical composition of fruits and vegetables includes polyhydric alcohols (sorbitol and mannitol), which have a sweet taste. They are found in large quantities of rowan, plum, and to a lesser extent in apples.

The sucking of fruits and vegetables also includes nitrogenous substances - proteins, amino acids, enzymes, nucleic acids, nitrogen-containing glycosides. The largest amount of proteins comes from olives (7%), legumes (5%), potatoes (2-3%), and nuts. Most fruits and vegetables contain less than 1% protein.

Fruits and vegetables are the main suppliers of enzymes.

1. Classification of fresh fruits and vegetables. Characteristics of individual species

When classifying fruits, two main characteristics are used - a sign of structure and a sign of origin.

By structure they are distinguished:

• Pome fruits (apples, rowan, pear, quince); they all have a skin, inside the fruit there is a five-locular chamber containing seeds;
• Stone fruits - their structure is characterized by the presence of skin, fruit pulp and a drupe containing a seed; stone fruits include plums, cherries, apricots, peaches, etc.;
• Berries - this group is divided into 3 groups: true berries, false and complex ones. For real berries: currants, grapes, gooseberries, cranberries, blackberries, lingonberries, blueberries. In real berries, the seeds are immersed directly in the pulp. Strawberries and strawberries are considered false berries. Their seeds are located on the skin. Compound berries consist of many small berries fused together on one fruit stem. This group includes raspberries, blackberries, stone fruits and cloudberries;
• Nut fruits, which are divided into true nuts (hazelnuts) and drupes (walnuts, almonds). All nuts consist of a kernel enclosed in a woody shell. On the surface of drupe nuts there is green pulp, which gradually darkens and dies as it matures.

According to their origin, fruits are divided into subtropical (among them there is a group of citrus fruits) and tropical. Many subtropical and tropical fruits require high temperature storage, and at cold temperatures they get cold and freeze. For example, bananas can be stored at a temperature not lower than +11 degrees. Pineapples - not lower than +8 degrees.

Fresh vegetables are divided into 2 groups: vegetative and generative, or fruit and vegetable. Vegetables whose leaves, stems, roots and their modifications are eaten are classified as vegetative. And vegetables whose fruits are used for food are called generative.

Among vegetative vegetables, depending on the part used for food, they are distinguished:

• tuberous (potatoes, bata, Jerusalem artichoke);
• root vegetables (beets, radishes, carrots, radishes, turnips, parsley, rutabaga, celery, parsnips);
• leafy vegetables (white cabbage, kohlrabi, cauliflower, Brussels sprouts, Savoy);
• onion vegetables (onions, onions, spring onions, garlic);
• salad-spinach (spinach, lettuce, sorrel);
• spicy vegetables (tarragon, basil, cilantro, dill, celery);
• dessert (artichoke, asparagus, rhubarb).

Generative vegetables are divided into the following subgroups:

• tomato (tomatoes, eggplants, peppers);
• pumpkin (cucumbers, pumpkin, zucchini, melons, watermelons, squash);
• legumes (peas, beans, beans);
• grain vegetables (sweet corn).

1. Transportation and receipt of fresh fruits and vegetables

When transporting fresh fruits and vegetables, it is necessary to comply with specific requirements due to their properties. In particular, transportation of fresh fruits and vegetables without packaging is not allowed. Some fruits and vegetables (potatoes, cabbage, beets) are transported in bulk during the period of mass procurement. When transporting watermelons without packaging, they must be covered with straw.

When accepting fresh fruits and vegetables, their quality is assessed based on general and specific indicators in accordance with current instructions. General indicators include appearance and size. Deviations in size are allowed only within normal limits.

Specific indicators include:

• The degree of maturity, which is divided into consumer, volumetric and physiological. Cucumbers are sold only at consumer ripeness; physiological ripeness is not allowed. For some fruits (apples late varieties) the volumetric physiological degree of maturity is the same;
• Taste and smell;
• The density of the bunch, the presence of broken clusters, the number of crumbled berries;
• Humidity (determined only for nuts);
• Consistency (for bananas and oranges).

During the acceptance of fruits and vegetables, sorting is carried out, and the following quality categories are distinguished:

• Standard fruits and vegetables - meet the requirements of current standards; this also includes defective fruits and vegetables within acceptable deviations;
• Non-standard fruits and vegetables with defects, limited by permissible standards, but in excess of established standards;
• Waste with defects not allowed by standards.

1. Processes suitable for storing fresh fruits and vegetables

During storage, various physical and biological processes occur in fruits and vegetables, such as moisture evaporation, respiration, ripening, healing and thickening of the skin, and hydrolytic decomposition of complex organic substances.

Breathing is the most important biochemical process and serves as a source of energy for metabolic processes. Respiration is accompanied by the loss of mass of fruits and vegetables, the release of energy, heat and moisture. During the process of respiration, a change in the gas composition of the environment surrounding the product occurs, significant losses of both the quantity and quality of fresh fruits and vegetables.

The intensity of the respiration process depends on the type of fruits and vegetables, their physiological state (degree of ripeness, freshness, presence of damage, moisture content) and storage conditions (temperature, light and gas composition of the environment).

Respiration can be oxygenated (aerobic) or oxygen-free (anaerobic).

Hydrolytic processes: hydrolysis occurs under the influence of enzymes, and always in the presence of water.

1. Factors affecting food safety

fruit vegetable nutritional value

Temperature is one of the most important conditions for storing food. Temperature affects the intensity of all processes. As the temperature rises, water evaporation increases, enzyme activity increases, chemical reactions accelerate, and conditions are created for the development of pests.

Optimal temperatures for different products their. Their range ranges from -18 to +25 degrees. For most products, freezing almost completely eliminates the occurrence of harmful chemical processes, although there are some for which the optimal temperature is from 0 to +4 degrees and its fluctuations are extremely undesirable.

Air humidity. This factor is closely related to temperature. The choice of relative humidity depends on the product. Dry foods require low humidity (65-70%) and 85-90% humidity is recommended for high-moisture foods.

Gas environment. The increased oxygen content in the gas environment and its contact with the product lead to the oxidation of fats (staff) and a change in the color of wines. The gas composition of the medium can be changed. Oxygen must be excluded from the gaseous environment. The inclusion of inert gases in the gas composition of the medium, on the contrary, has a positive effect on the storage of many products.

Most often, a controlled gas environment is used when storing fresh fruits and vegetables. The proportion of oxygen in it decreases, and the proportion of carbon dioxide increases. This leads to a delay in the processes of ripening and over-ripening, a decrease in the activity of microbiological diseases, and the consistency of the products is better preserved.

In addition to the controlled gas environment, a modified gas environment is used. It involves the use of polymer films with a selective environment.

Light. Almost all food products require the absence of light. For example, when storing potatoes in the light, a toxic green substance - corned beef - is formed on the surface of the tubers. Light destroys vitamins and negatively affects the properties of colored products, especially when natural dyes are used.

Ventilation is most important when storing plant products. There are natural, artificial and forced ventilation. The latter is used in modern vegetable stores and provides best preservation products.

Sanitary regime. It includes measures for disinfection and pest and rodent control.

Quality of packaging materials.

6. Nutritional value of fruits and vegetables

The nutritional value and organoleptic (taste and aroma) properties of vegetable fruits are determined by those chemicals, of which they are composed.

Products of plant origin include proteins, fats, carbohydrates, vitamins, organic acids, minerals and trace elements.

The predominant component of all raw materials is water. Its fruits contain 75-90%, and vegetables - 65-96%.

Squirrels. Protein substances play a large role in human nutrition. The main sources of proteins are meat and fish. Vegetables and fruits have relatively low protein content. However, due to the special significance protein nutrition plant products should be used as an important additional source of proteins.

Fats are important in nutrition. The fat content in the tissues of fruits and vegetables is very low; they are contained in significant quantities in seeds. Vegetable oils contain essential linoleic and linolenic acids, which have greater biological value and are better absorbed by the body than animal fats.

Carbohydrates are energy sources and serve as reserve nutrients for the human body. Among plant materials, fruits are especially rich in carbohydrates. They contain carbohydrates mainly in the form various sugars(sucrose, glucose, fructose) and starch. During a normal diet, the bulk of carbohydrates enters the body in the form of starch, and only a small part - in the form of sugar. Starch in the body turns into glucose, which is absorbed into the blood and nourishes the body's tissues.

Vitamins are substances necessary for the normal functioning of the human body. They increase the body's performance and resistance to infectious diseases, and have a positive effect on its growth and development.

Vitamin C is an anti-scorbutic agent and is necessary for proper growth and development of the body.

The main source of vitamin C is vegetables, fruits, berries, rose hips, black currants, lemon, orange, etc.

Vitamin A is one of the most important and abundant vitamins that ensures normal growth of the body. The lack of this vitamin in the human body reduces its immunity to various infections.

Vitamin A is found in free form only in liver fat. sea ​​fish and whales. Plant raw materials do not contain vitamin A, but contain provitamin A - carotene, from which vitamin A is formed when decomposed in the human body. Apricots, black currants, red sweet peppers, plums, carrots, spinach, red tomatoes and green peas are rich in carotene.

Vitamin B1 is found in almost all fresh fruits and vegetables, baker's and brewer's yeast. The absence or deficiency of this vitamin in the body causes a disorder of the nervous system.

Vitamin B2 is contained in carrots - 0.005 - 0.01 mg per 100g, in cabbage, onions, spinach, tomatoes up to 0.05 mg per 100g.

Vitamin D is extremely important for children, since insufficient levels of it in food lead to rickets. This vitamin is found only in animal products.

The richest sources of vitamin D are fish oil, animal and bird liver. Vitamin D is found in milk, butter and egg yolks.

Vitamin E is widely distributed in nature; it is found not only in animal products, but also in many plant foods. The germs of cereals and green leaves of plants are richest in vitamin E.

Organic acids. All fruits and vegetables contain some kind of organic acid.

Organic acids play an important role in metabolism. In the human body, they dissolve some unwanted deposits.

Meat and fish contain lactic acid. The most common acids in fruits and vegetables are malic, citric, tartaric and other acids.

Malic acid predominates in pome fruits, as well as in dogwoods, apricots, peaches, tomatoes and berries. Citrus fruits and cranberries contain a lot of citric acid. Tartaric acid is found in grapes. Sorrel and rhubarb are rich in oxalic acid.

Minerals. The main minerals are salts of calcium, sodium, potassium, iron, as well as sulfur, phosphorus and chlorine. Mineral salts are contained in every cell of a living organism. Without them, just like without water, life is impossible.

Mainly lettuce, cabbage, strawberries, apples, potatoes, peas, fish, meat, eggs are rich in iron salts; potassium salts - radishes, spinach, carrots, cabbage, oranges, lemons, tangerines. Correct and rational use of products, as well as the implementation of recommended processing regimes during canning, make it possible to almost completely preserve the nutrients and vitamins contained in them.

Conclusion

Having carefully studied the above material, I can draw the following conclusions.

Some fruits and vegetables have a large amount of moisture, therefore, they cannot be stored for a long time, because... moisture is a good breeding ground for putrefactive bacteria and microbes.

There are two main features of fruit classification:

• By structure
• By origin.

During storage, various physiological and biological processes occur in fruits and vegetables, such as moisture evaporation, respiration, ripening, healing and skin thickening.

The safety of fruits and vegetables is influenced by factors such as: temperature, air humidity, gas environment, light, ventilation, sanitary conditions, and the quality of packaging materials.

Bibliography

1. Commodity research of food products Marina Burova - M.: PRIOR Publishing House, 2000. - 144 p.
2. Home canning G.G. Tokarev. - D66 St. Petersburg: Polygon Publishing House LLC, 2004. - 220 p.: ill.

Fruits, berries and vegetables play a big role in human nutrition. Due to the content of carbohydrates, mainly sugars, organic acids, vitamins, tannins, etc., they are valuable products nutrition. All fruits and vegetables, depending on their structure, are divided into several groups, which differ significantly in nutritional properties and shelf life.

Vegetables are divided into fruit (pome-bearing) and vegetative, fruits - into pome-bearing, stone fruit and berries. Fruits and fruit vegetables are the succulent fruits of plants. The main part of them is fruit pulp, containing, to a greater or lesser extent, cell sap. Therefore, fruits, especially ripe ones, quickly lose their stability and are subject to spoilage under the influence of a wide variety of microorganisms.

Another group - vegetative vegetables: leafy, bulbous, cabbage - are shoots of a plant or its leaves developed to varying degrees (spinach, sorrel, onions, garlic, cabbage). Root and tuber crops - modified, overgrown and filled with reserves nutrients roots and underground stems of vegetable plants (carrots, beets, potatoes).

Vegetables related to tubers and root crops are plant organs whose development cycle is not completed, since in the future they must produce fruit-bearing plants (form seeds), therefore their natural resistance (natural immunity) to the effects of microorganisms is much higher than that of fruits.

The chemical composition of fruits and vegetables is quite complex. Thus, vegetables and fruits contain a lot of water - from 65 to 95%, depending on the degree of ripeness and variety. Water makes up the bulk of cell sap; dry substances - organic and mineral compounds - are dissolved in it.

The dry matter content in fruits and vegetables ranges from 10-20%. The exception is some grape varieties that can accumulate a lot of sugar and develop raisins. The dry matter content in the juice of such grape varieties can reach 30% or higher. Vegetables contain relatively high amounts of dry matter: carrots (on average 14%), green peas (up to 20%), corn (25% and above).

The most important component of cell sap is sugar (mono- and disaccharides - glucose, fructose, sucrose). Fruits accumulate from 8 to 12% sugar, only grapes, as indicated, can accumulate much more: on average 16-18%, and some varieties (for example, Muscat) up to 25-30%. Vegetables contain much less sugar - an average of 4%. Root vegetables (carrots, beets) have higher sugar content.

A significant portion of the dry matter in fruits and vegetables comes from starch. By the time of full ripeness, starch disappears in berries and fruits, and in many vegetables, on the contrary, it accumulates. Thus, potatoes (12-15%), green peas and other legumes, as well as sweet corn are rich in starch. Both sugar and starch are energy sources of food, consumed during respiration, and play an extremely important role in human life. Other carbohydrates found in fruits and vegetables include cellulose, pentoses, pentosans, and pectin substances that are part of cell walls.

A very important component of fruit juice are organic acids, the content of which varies greatly depending on the variety and degree of ripeness of the fruit. In wild apples, the content of malic acid reaches 2%, while in some sweet (cultivated) varieties its content does not exceed 0.05%. The most common are apple and citric acid. Tartaric acid is found in large quantities only in grapes, and is usually absent or contained in small quantities in other fruits and berries.

Many fruits and vegetables accumulate aromatic substances (essential oils), which determine their aroma and, apparently, affect the taste. Spicy vegetables are very rich in aromatic substances - parsley, celery, dill, as well as onion vegetables - onions, garlic and, finally, citrus fruits - lemons, oranges, etc. The content of aromatic substances in vegetables ranges from 0.05 to 0.5%: So, for example, they contain 0.05% in onions, about 0.01% in garlic, and in the peel of tangerines essential oil contains from 1.8 to 2.5%.

Considering that fruits and vegetables contain various enzymes and vitamins that contribute to the normal course of life and digestive processes, then their nutritional value will increase even more. If animal products are suppliers of proteins, then fruits and vegetables are suppliers of vitamins - extremely important substances vital for humans. A lack of vitamins in animal and human food causes metabolic disorders in the body, and their complete absence leads to various serious diseases (vitaminosis). Many vitamins combine with proteins to form enzymes that promote digestion. Onions, for example, contain a proteolytic enzyme that can break down proteins into peptones. Cabbage and some root vegetables contain an enzyme similar to trypsin. Almost all vegetables contain amylase, which saccharifies starch, and are rich in oxidase and catalase. Sufficient amounts of oxidase and catalase are also found in fruits.

Dying substances that give fruits and vegetables a particular color are also of great importance. There is evidence that brightly colored fruits are more resistant to microorganisms.

The juices of various higher plants also contain some volatile fractions - phytoncides, which have a bactericidal effect. In some plants, the presence of phytoncides is associated with the presence of a strong smell and taste (onions, garlic), while in other plants this is not observed (tomatoes, carrots).

In addition to organic compounds, plant tissues also contain minerals. Fruits contain mineral, or ash, elements from 0.2 to 1.8%. Minerals are of great physiological importance and are necessary components of food. Thus, iron is part of blood hemoglobin, calcium is part of bones, phosphorus is necessary for the normal functioning of nerve tissues, etc. Due to their chemical composition, fruits and vegetables are an excellent nutrient substrate for many microorganisms.