It is a hormone of aging and fruit ripening. Ripening of fruits and vegetables

Plant hormones are called phytohormones. Phytohormones are chemical compounds with the help of which the interaction of cells, tissues and organs is carried out and which in small quantities are necessary for the regulation of all life processes of plants. Plant hormones are low molecular weight compounds that are active in very low concentrations (10 -13 -10 -5 mol/l). They, as a rule, are formed in one part of the plant and transported to another, where they have a strong impact on the processes of growth and development of the plant organism.

Despite the variety of functions of certain hormones, they can be combined into two groups: stimulating hormones And hormone inhibitors. The most important stimulants include auxins, gibberellins and cytokinins, and inhibitors include abscisic acid and ethylene.

Auxins substances of indole nature are called: indolylacetic acid and its derivatives. The precursor to auxins in plants is one of the essential amino acids, tryptophan. The synthesis of auxin from tryptophan is under the control of other plant hormones - gibberellins (they activate synthesis) and ethylene (suppresses synthesis). Auxins are synthesized mainly in the apical systems (growth points) of the stem and root. They accumulate most of all in growing buds and leaves, pollen and developing seeds. Auxin has a strong influence on flowering, growth and ripening of plant fruits. Auxin contained in pollen is essential for the growth of the pollen tube and therefore for plant pollination. Transport of auxins in a plant occurs strictly polarly: down the stem from the tip of the shoot to the tip of the root - to the zone of its elongation. Auxin flows from the leaves also flow here. Auxin is one of the most ancient phytohormones. It is known that even primitive flagellated organisms have a regulatory chemical compound - serotonin, very similar in structure to auxin, which plays the role of an intracellular hormone. In highly organized animals, serotonin is one of the neurotransmitters. Auxins are used in plant growing to stimulate root formation in cuttings of trees, shrubs and herbaceous plants (currants, gooseberries, cherries, grapes, jasmine, roses, etc.), as well as to improve the fusion of scion and rootstock during grafting.

Gibberellins. The name of these phytohormones comes from the Latin name of the gibberella fungus from the class Marsupials (Gibberella fujikuroi). This mushroom produces hyberellic acid, which was discovered (in 1926) in Japan. Gibberellins are synthesized especially intensively in growing (apical 9-apical) stem buds of plants, in leaf chloroplasts, in developing seeds, and in the embryo of germinating seeds. The physiological functions of gibberellins are varied. They have a strong influence on the intensity of mitosis and cell elongation. Under the influence of gibberellins, the stem and leaves lengthen, and the flowers and inflorescences become larger. The grapes produce larger clusters.

Gibberellin has a powerful effect on plant flowering. It turned out that for plants to flower, a certain concentration of gibberellin in tissues is necessary. This concentration occurs either during long daylight hours or at low temperatures (during vernalization). Therefore, treatment with gibberellin accelerates the flowering of long-day plants: they can be “forced” to bloom even with short daylight hours.

Gibberellin has the strongest effect on the emergence of plants from a state of physiological dormancy. The seeds and tubers of many plants are dormant after harvesting and do not germinate even under favorable conditions of moisture, oxygen and heat. However, treatment with gibberellin causes their germination.

Gibberellin also awakens dormant buds of overwintering herbaceous and tree-shrub plants. Treatment with gibberellin allows, for example, to obtain flowering shoots of jasmine, lilac or lily of the valley in the middle of winter. This method in plant growing is called plant forcing.

High physiological activity of gibberellins manifests itself during the formation of juicy fruits. As it turned out, seeds developing after fertilization produce gibberellins necessary for growth and fruit formation. The lack of active gibberellins at this critical moment causes a delay in fruit growth. Additional treatment with gibberellin, on the contrary, promotes the formation of large seedless (parthenocarpic) fruits in tomato, grapes, peppers, citrus fruits, pome and stone fruit crops.

Cytokinins. Cytokinins are phytohormones, purine derivatives, which have a strong stimulating effect on plant growth and development. The main site of cytokinin synthesis is the apical meristem of roots. They are also formed in young leaves and buds, in developing fruits and seeds.

It is noteworthy that cytokinins are synthesized not only by plants, but also by some microorganisms associated with plants. Thus, nodule bacteria settle on the roots of leguminous plants. Their tissues are enriched with cytokinins and auxins, which leads to an influx of nutrients and the formation of nodules.

Cytokinins in plants stimulate cell division, accelerate the growth of cells in dicotyledonous (but not monocotyledonous) plants in length, and promote their differentiation. The physiological activity of cytokinins is based on enhancing the synthesis of DNA, protein, growth and development of chloroplasts and other cell organelles. Cytokinins stimulate the growth and development of shoots, but inhibit root growth. This is their difference from the action of auxins.

Like gibberellins, cytokinins have a high “awakening” ability: they bring seeds and tubers, dormant buds of trees and shrubs out of a state of deep dormancy, and increase the germination of seeds of peas, corn, barley and many other plants.

Cytokinins delay the aging of leaves, increase the supply of nutrients to tissues, due to which the structure of chloroplasts is restored, and the synthesis of chlorophyll, RNA and protein in them is enhanced. The intensity of photosynthesis increases.

Abscisic acid. If auxins, gibberellins and cytokinins are stimulators of plant growth and development, then abscisic acid is the most important plant inhibitor with a wide spectrum of action. Abscisic acid (ABA) is synthesized in almost all plant organs, especially in aging ones. ABA is an antagonist of stimulating hormones. Thus, the transition into dormancy of seeds, tubers, bulbs and buds is associated with an increase in the ABA content in them.

As it turns out, the plant responds to shortening daylight hours and the approach of winter by accelerating ABA synthesis. During this period, the content of this hormone increases in the wintering organs of perennial legumes and cereal grasses, and winter grains. At the same time, the activity of auxins, gibberellins and cytokinins is suppressed. This prevents excessive physiological activity of plants preparing for winter.

The aging of plants and the ripening of tomato, strawberry, pear, grape and other crops is associated with a significant concentration of ABA: the phytohormone accelerates the breakdown of proteins, nucleic acids, and photopigments.

As it turned out, abscisic acid is involved in such an important process as the regulation of stomata. When leaves are dehydrated, their ABA content rapidly increases. This causes the stomata to close, resulting in decreased transpiration.

The dynamic balance in plant cells between the inhibitory effect of ABA, on the one hand, and the stimulating effect of auxins, cytokinins and gibberellins, on the other hand, serves as a necessary condition for normal plant growth and development. A unique system of mutual inhibition of antagonist hormones is created, as a result of which the metabolism of the plant organism acquires the necessary stability.

Ethylene. The well-known ethylene gas is a hormonal factor in the plant organism. It is formed from the amino acid methionine in almost any plant organ, but the rate of its biosynthesis is still highest in aging leaves and ripening fruits. The physiological functions of ethylene in plants are diverse. Ethylene promotes tissue aging and thereby accelerates the fall of leaves and fruits. In case of local damage, the plant synthesizes the so-called “stress ethylene”, which promotes the rejection of damaged tissue. Ethylene increases the dormancy of seeds, tubers and bulbs, and also accelerates the ripening of fruits. Therefore, ethylene is used to accelerate the ripening of fruits, for which they are placed in specially hermetically sealed chambers filled with this gas.

Ethylene affects the generative organs of plants, in particular, it promotes a shift in the sex of dioecious plants towards the female side. This leads, for example, to a change in the ratio of female and male cucumber flowers and helps to increase its yield. Ethylene, as a gaseous compound, has high mobility in plant tissues. Therefore, quickly spreading throughout the plant, it has a regulatory effect on the work of other phytohormones, enhancing or, conversely, suppressing their physiological activity.

Thus, the hormonal system of plants is multicomponent. The ratio of activator hormones and inhibitor hormones naturally changes during the individual development of plants, as well as in response to changes in environmental factors. In this regard, phytohormones are extremely important for increasing plant resistance to unfavorable factors. The general pattern is as follows: in the case of stress, the role of inhibitor hormones (abscisic acid and ethylene) predominates, and when the plant exits the stressful state and transitions to normal life activity, the role of activator hormones (auxins, gibberellins and cytokinins) predominates.

The vast majority of plants are not capable of movement of the entire organism as a whole. However, under the influence of external stimuli, some plant organs can move or grow.

The growth of plants under the influence of external stimuli is called tropism. Tropisms can be positive or negative, depending on whether the response is directed towards or away from the stimulating factor. There are several types of tropisms:

Phototropism (light);

Geotropism (gravity);

Hydrotropism (water);

Chemotropism (chemicals);

Haptotropism (solid surface).

Nasties are various types of non-directional movement of a plant part in response to an external stimulus. Movement occurs as a result of an increase or change in turgor pressure. Among these types, one can distinguish nyctinasty (“sleepy movement”) - the opening and closing of leaves when the light or temperature changes, and haptonasty - a response to touch. Haptonasty is also distinguished by the fact that the transmission of the response to irritation occurs very quickly (sometimes it takes only a few seconds). Haptonastic movements also include some movements performed by insectivorous plants.

Taxis is the movement of the entire organism under the influence of an external stimulus (light, some chemical, gravity, magnetic field, oxygen, etc.). Characteristic only for bacteria, unicellular plants and plant germ cells.

Chemical coordination in plants is carried out by so-called growth substances, which can be considered an analogue of animal hormones. Currently, five main classes of growth substances are known.

Cytokinins stimulate cell division in growing shoots, promote fruit growth, slow down the aging process of leaves, and bring seeds and buds out of dormancy. The mechanism of action of these substances has not yet been studied. Cytokinins are used to increase the shelf life of green vegetables (cabbage, lettuce) and cut flowers.

Auxins (for example, indolylacetic acid) are formed at the growing point of the stem and in young leaves. Under the influence of diffusion, they move down the stem along the shady side, causing a decrease in extracellular pH in this area. The cell membrane stretches and water penetrates inside. The cell stretches and additional cell wall material is deposited. Thus, auxins cause phototropism. Geotropism causes a similar mechanism; The role of receptors that perceive gravity is apparently played by starch grains, deposited on the underside of the cell and influencing the distribution of growth substances. Different directions of geotropism depend on the concentration of auxin. Artificial auxins cause the death of broad-leaved plants (selective herbicides; this is used, for example, when treating crops of grain or lawns), promote fruit set (naphthylacetic acid), cause other effects. Gibberellins (for example, gibberrelinic acid) also cause plant growth by cell elongation ( especially in the presence of auxin). In addition, in germinating seeds they contribute to the breakdown of starch, the products of which are used for growth. The mechanism of action of gibberellins is still not clear. Artificial gibberellins are obtained from fungi and are used for growing seedless grapes and used in brewing. Abscisic acid is formed in leaves, stems, fruits and seeds and is transported through the phloem. It inhibits plant growth, stimulates stomatal closure and leaf fall. A high concentration of abscisic acid completely stops growth. The mechanism of its action is unknown. Abscisic acid is sometimes sprayed on trees to cause simultaneous fruit drop. Ethylene C2H4 is formed in various plant organs. It stimulates fruit ripening and inhibits growth processes. In agriculture, it is used to control the ripening of harvested vegetables and fruits.

ALL-RUSSIAN OLYMPIAD FOR SCHOOLCHILDREN

I(SCHOOL) STAGE

Biology 7th grade

Task No. 1. The task contains questions, each of which has several answer options; among them only one is faithful. Mark the correct answer.

1. In plants, metamerism (repetition of areas with the same structure) is characteristic:

a-only for escape; b- only for the root;

c - only for root and shoot; d- for algae thalli.

2. Living cells are often absent from plant tissues:

a - cover; b - main; c - mechanical; g - storage.

3. The seeds contain a small amount of fat.

a - hemp; b – flax; c - peas; g - sunflower.

4. The root performs the function:

a – mechanical; b – suction; c – conductive; g - all these functions.

5. Carrots have:

a – root tuber; b – rhizome; c – tuber; d – root vegetable.

6. Accessory buds can be located on:

a – internodes; b – roots; c – leaves; d - all these parts of the plant.

7. Fruit ripening in plants is stimulated by:

a) ethylene; b) gibberellins; c) cytokinins; d) auxins

8. Guard cells form:

a – stomata; b - columnar fabric; c - spongy tissue; d. conductive bundles.

9 .The formation of organic substances from inorganic ones using solar energy occurs in plants in the process

a) photosynthesis; b) breathing;

c) evaporation; d) transport of substances.

10. In insect-pollinated plants, pollen:

a – dry; b – sticky; c – small; g – light.

11. Double fertilization is typical for:

12. The taxonomic category of plants, which unites similar classes, is called:

a) view; b) family; c) birth; d) department.

13. Has juicy fruits:

a – peas; b – radish; c – rowan; g – sunflower.

14. Algae do not have:

a – stem; b – leaves; c – roots; d - all these organs.

15. Rhizoids serve for:

a - absorption of nutrients; b - vegetative propagation;

c - attachment to the substrate; d – photosynthesis.

16. Bryophyte plants include:

a – kelp; b - reindeer moss; c – sphagnum; g - all these plants.

17. Horsetail spores:

a – absent; b - ripen on shoots; c - ripen in spikelets at the tops of shoots; d - ripen on the surface of the leaves.

18. A bacterial cell lacks:

a – core; b – mitochondria; c - plastids; d - all these organelles.

19. Bacterial spores are most vulnerable to:

a - boiling; b – freezing; c – dehydration; g - ultraviolet radiation.

20. Mycelium cells supply the lichen body with:

a - water and organic substances; b - water and minerals;

c - exclusively with water; d - oxygen and carbon dioxide.

Task No. 2. The task contains questions, each of which has several answer options. Mark the correct answers.

1. Which of the following plants has an inflorescence that is a simple umbrella:

a – cherry; b – corn; c – dill; g – pear; d – rowan; e – celandine; g – dandelion; h – carrots; and – onion.

Answers: 1-a, f, h; 2-a,b,d,f; 3-b,d,e,f,g; 4-a, f, i, g.

2. The main characteristics of the dicotyledonous class:

a – the embryo usually has 2 cotyledons; b – leaves are always simple, veining is parallel and arcuate; c – fibrous root system; d – the root system is usually taprooted; e – flowers are usually three-membered, the perianth is simple; e – leaves are simple and compound, the veins are pinnate; g - flowers are usually five-membered, the calyx and corolla are well defined.

Answers: 1-a, d, f, g; 2-a, b, d, f; 3-a, d, f, g; 4-b,c,f,d,g

a – these are higher plants; b – stems and leaves have roots; c – there are flowers; d – form seeds; d – form fruits; e – closed position of the ovule; g – there is tissue differentiation.

1-a, b, d, f; 2-b,d,e,g; 3-a, b, d, g; 4-a, d, f, g

4. Which of the following characteristics do not correspond to bacteria:

a – presence of ribosomes; b – reproduce by indirect division; c – no membrane organelles; d – have one circular DNA molecule; e – there is a cell membrane; e – have several pairs of chromosomes.

Answers: 1-a,b,c; 2-b,f; 3-b,c,d; 4-a,d,e,f

a – chaga; b – russula; c – smut; d – late blight; d - candida fungus; e - penicillium; g – saffron milk cap; h – aspergillus.

Answers: 1-a,b,d; 2-d,e,f; 3-d,h; 4-d, d, f, g, h

Task 3.

You are offered a task that requires establishing compliance.

Match the plants listed below (1-10) with the classes of angiosperms.

Rye 6. Lupine

Pineapple 7. Bamboo

Cuff 8. Datura

Tradescantia 9. Lily of the Valley

Henbane 10. Horseradish

Answer. Monocots:

Dicotyledons:

2. For each plant shown on the left, identify its family.

A – wild radish

B – dill

B – potatoes

G – peas

Task 4. You are offered an open-type task that requires a detailed answer.

Give examples of aquatic angiosperms (2-3 examples). What are the structural features of the root, stem, leaves in connection with the aquatic lifestyle of these plants?

ANSWERS TO BIOLOGY TASKS 7TH GRADE.

Exercise 1

Maximum points 20 points, 1 point for each test task.

Correct answers: 1 – a; 2 – in; 3 – in; 4 – g; 5 – g; 6 – g; 7 – a; 8 – a; 9 – a;

10 – b; 11 – g; 12 – g; 13 – in; 14 – g; 15 – in; 16 – in; 17 – in; 18 – g; 19 – g; 20 – b.

Task 2 Maximum points 10 points, 2 points for each test task.

Correct answers: 1) 1- a, e, and; 2) 1 – a, g, f, g; 3) 3– a, b, d, g; 4) 2– b, f; 5) 3 – d, h.

Task 3

1. Maximum points 10 points, (For each correct distribution 5 points).

Dicotyledons 3,5,6,8,10.

Monocots1,2,4,7,9.

2. For the correct definition of the family 8 points, 2 points for each correct definition.

Task 4.

Answer. Hornwort, water lily, yellow egg capsule, common water lily, Canadian elodea (1 point). The root system of aquatic plants is poorly developed, there are no root hairs: water with minerals dissolved in it can penetrate directly into the leaves (1 point). A significant increase in the surface of the body, which facilitates the absorption of the necessary quantities of oxygen and other gases, which are contained less in water than in air. An increase in the surface of the plant is achieved by the development of large thin leaves, the division of the leaf blade into thin thread-like sections, the strong development of air cavities and large intercellular spaces. The high density of the aquatic environment causes poor development of mechanical elements in the leaves and stems of aquatic plants; In aquatic plants, vessels in vascular bundles are poorly developed or even absent. (2 points). Submerged leaves do not have stomata; in leaves floating on the surface of the water, stomata are located only on the upper side, in above-water (aerial) leaves, stomata are on both sides. Since the light intensity in water decreases sharply, many aquatic plants have chlorophyll grains in their epidermal cells (1 point). (5 points)

The maximum amount of points for 4 tasks for grade 7 is – 53 points.

e, as a result of which the seeds become full-fledged rudiments of new plants, and the pericarp acquires the ability to perform the functions of protecting and spreading seeds. After pollination of flowers, fruit plants form an ovary, which begins intensive growth. Inside the ovary, the formation and maturation of seeds occurs, which also contributes to the growth and maturation of the pericarp, which occurs differently in dry and juicy fruits. In dry fruits, this process comes down mainly to tissue dehydration. Thus, in legumes, the pericarp shrinks and decreases in size; in cereals, the drying pericarp fuses with the seed coat. In juicy fruits, the pericarp grows due to the tissues of the ovary or receptacle. In this case, there is an increase in the number of cells, their size, as well as the formation of intercellular spaces. There are two main periods of fetal development: the first - from fertilization of the egg to the maturation of the seeds and the end of the growth of the pericarp, the second - until the complete maturation of the pericarp. In the first period, there is increased growth and formation of seeds and pericarp, accompanied by an intense influx of nutrients and water from the leaves. In seeds and fruits, the processes of synthesis of high-molecular substances predominate: proteins, fats, carbohydrates (starch, cellulose, pectin substances). In the second period, the morphological and biochemical characteristics of the fruit change: it softens, acquires its characteristic color, taste and aroma. The breathing process, which supplies energy to the fetal tissues, plays a major role in these changes. A characteristic feature of many types of fruits is the so-called. climacteric rise in breathing. In some fruits it is observed before they are removed from the tree, in others (ripening in storage) - after it. The rise in respiration is promoted by the formation of ethylene in fruits. During the ripening period, the content of starch, organic acids and phenols (tannins) decreases and nitrogenous compounds and soluble sugars accumulate; as a result, the taste of the fruit is formed. The softening of fruits depends on changes in the ratio and state of polysaccharides, especially pectin substances (See Pectin substances), in the cell walls. During ripening, the composition of pigments included in the skin, pulp and cell sap of the fruit changes: Chlorophyll is usually destroyed and Carotenoids are synthesized. Anthocyanins and other pigments. Thanks to the synthesis of alcohols, aldehydes, esters, and terpenes, the fruit acquires its characteristic aroma. Regulation of S. processes is carried out by phytohormones produced by plants (See Phytohormones). After the climacteric rise in respiration, aging and overripening of the fruit occurs.

In stone fruits, berries, bananas, and figs, the S. period is short, in citrus fruits it is long. For apples and pears, this period varies widely depending on the variety (summer, autumn, winter). For transported and stored fruits, two degrees of maturity are distinguished: removable and consumer. S. p. is influenced by environmental factors - temperature, light, and the gas composition of the environment, which is especially evident during post-harvest S. p. (see Fruit ripening).

Lit.: Tserevitinov F.V., Chemistry and merchandising of fresh fruits and vegetables, 3rd ed., vol. 1, M., 1949; Biochemistry of plants, trans. from English, M., 1968, ch. thirty; Leopold A., Growth and development of plants, trans. from English, M., 1968, ch. 17; Metlitsky L.V., Biochemistry of fruits and vegetables, M., 1970; Sapozhnikova E.V., Pectic substances and pectolytic enzymes, M., 1971.

E. V. Sapozhnikova.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .

See what “Ripening of fruits” is in other dictionaries:

Set of morphol., biochemical. and physiol. changes in plant fruits, as a result of which the seeds become full-fledged rudiments of new plants. S. p. begins after flowering and sometimes ends after the fruits are picked (for example, in a tomato). IN… … Biological encyclopedic dictionary

MATURATION, maturation, plural. no, cf. Action under Ch. ripen. Fast ripening of fruits. Idea maturation. Ushakov's explanatory dictionary. D.N. Ushakov. 1935 1940 ... Ushakov's Explanatory Dictionary

Maturation is a natural process of transformation of the anatomical structures and physiological processes of the body as it grows. In everyday life, ripening most often refers to the ripening of fruits. Contents 1 Fruit ripening 2 Sexual ... Wikipedia

MATURATION- in plants, concludes. stage of development of seeds and fruits. At the beginning of the S. period, increased growth and formation of seeds and pericarp occurs, there is an intense influx of assimilates and water from vegetative organs to generative organs, and the synthesis of high-molecular... ... Agricultural Encyclopedic Dictionary

maturation- in plants, the final stage of development of seeds and fruits. At the beginning of the S. period, increased growth and formation of seeds and pericarp occurs, there is an intense influx of assimilates and water from vegetative organs to generative organs, synthesis... ... Agriculture. Large encyclopedic dictionary

maturation- see mature; I; Wed Ripening of fruits. Spiritual maturation… Dictionary of many expressions

You can keep the fruit on the tree until natural ripeness, that is, to a state in which the fruit itself is ready to separate from the tree; on the contrary, you can pick the fruits unripe and let them ripen in storage. Natural ripening... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

CROWN- see Early ripening. Recommended for fresh use. Fruit ripening occurs on days 105-113 after full germination. The plant is non-standard, determinate, erect, weakly branched, weakly leafy, 15-20 cm high, medium... ...

Ethene, H2C=CH2, unsaturated hydrocarbon (See Unsaturated hydrocarbons), the first member of the homologous series of olefins (See Olefins), colorless gas with a faint ethereal odor; tnl 169.5°С, tkip 103.8°С, density 0.570 g/cm3 (at tkip);… … Great Soviet Encyclopedia

ARAN-735- see Early ripening. Recommended for fresh use. Fruit ripening occurs on days 102-115 after full germination. The plant is non-standard, determinate, medium-branched, medium-leaved, 46-74 cm high, medium size,... ... Encyclopedia of seeds. Vegetables

The quality of fruits and vegetables used for canning is largely determined by their ripeness.

During the ripening process, organic substances accumulate in the raw materials, which undergo biochemical transformations under the action of enzymes. Due to this, continuous changes occur in the structure of plant tissue and its chemical composition.

As organic matter enters, fruits form and their size and weight gradually increase. This is the result of growth both in the total number of cells and in each of them individually. At the same time, seeds appear and develop in the fruits.

The dynamics, and to a certain extent the nature of the changes that occur in fruits and vegetables during ripening, depend on the type of raw material. During the maturation process, the following main changes in the chemical composition of the raw material occur.

The total amount of pectin substances increases. At the same time, the amount of protopectin in pome fruits decreases and the content of soluble pectin increases. In stone fruits and some berries (currants), with an absolute increase in the amount of pectin substances, their percentage content decreases, which is explained by the rapid accumulation of sugars and other soluble substances. In cherries, cherries, and currants, the amount of protopectin increases as they ripen, which is also observed in some varieties of apricots and plums, while in other varieties of the same fruits the amount of soluble pectin increases.

Sugars transferred from leaves to fruits form starch and other polysaccharides, which are then converted back into sugars. So, when apples, apricots, peaches, grapes, gooseberries, and tomatoes ripen, the amount of sugar in them increases. In green peas, green beans, and corn grains, sugars turn into starch during the ripening process. Unripe cucumbers contain the maximum amount of sugar.

In some types of stone fruits (apricots, peaches, plums), sucrose is synthesized from monosaccharides during ripening. In melons and melons, glucose first appears, then it turns into fructose, and by the end of ripening, sucrose accumulates.

In tomatoes, the opposite phenomenon is observed: the sucrose contained in unripe fruits is hydrolyzed as they ripen, turning into invert sugar. The amount of acids in raw materials usually gradually decreases. At the same time, in some fruits (peaches, cherries), the acidity increases as they ripen. Unripe grapes contain a lot of free tartaric acid, which, when the raw materials ripen, reacts with potassium to form salts (potassium tartrate). When fruits become overripe, the amount of acids may increase due to the breakdown of carbohydrates.

During the ripening process, aromatic coloring substances and vitamins accumulate in the fruits.

The accumulation of carotene in carrots and tomatoes ends by the time they are fully ripe.

When fruits become overripe, irreversible changes occur in the cells. The turgor phenomenon is disrupted. The tissue softens, becomes flabby, and easily susceptible to the action of microorganisms. Complex organic substances are transformed into simpler ones, and the amount of sugars decreases. Overripe fruits have reduced taste, are easily boiled during technical processing and are unsuitable for canning.

Since the taste, nutritional value and appearance of raw materials depend on the stage of fruit development, it is important to determine their optimal maturity in each individual case.

The physiological maturity of fruits is characterized by the presence of mature seeds in the raw material. To establish the time of raw material removal, this indicator is usually not used, but rather resort to the concepts of consumer and technical stage of maturity. At the consumer stage of maturity, raw materials are most suitable for direct use as food. Technical maturity ensures the best quality of canned products obtained from fruits and vegetables.

The concept of technical maturity is very relative. This indicator depends not only on the type of raw material, but also on its purpose. For example, green tomatoes can be used for pickling, red or brown (slightly unripe) tomatoes can be used for stuffing, but only red (ripe) fruits are suitable for producing juice and paste. The stage of technical maturity sometimes coincides with consumer maturity.

The most characteristic signs by which the maturity of raw materials is determined are the size of the fruit, density, color, taste and aroma, consistency, and seed development. Most of these indicators are determined organoleptically.