Cottage cheese is the most valuable and delicious fermented milk product, its benefits for the body are invaluable. It occupies a worthy place among the many products that are necessary to maintain a normal state. human body.

This fermented milk product is obtained by fermenting whole milk, followed by the removal of whey. Cottage cheese is nutritious, absorbed by the body almost completely.

Due to its excellent taste, cottage cheese is added to various dishes, and is also eaten in pure form. Cottage cheese is rightfully considered one of the most popular fermented milk products. It is an indispensable component of a complete diet for people of all ages.

Cottage cheese is distinguished by the% fat content in it:

• Fat cottage cheese (fat content index 1, 180) - 226 kcal
  
• Bold cottage cheese(fat index 0.090) - 160 kcal
  
• Low-fat cottage cheese (fat content 0.006) - 86 kcal
  
• Skim cheese(fat index 0.0011) - 70 kcal
  
• For an adult, the consumption rate per day is 200 - 250 grams per day.

Useful properties of cottage cheese:

The amount of protein found in other fermented milk products is less than in whole cottage cheese. Cottage cheese saturates the blood with useful substances, helps to normalize metabolic processes inside tissues and organs, improves digestion, and does not irritate the mucous membranes. pain in the stomach.

The special benefit of cottage cheese is that it contains a lot of calcium and phosphorus, these components are very useful for the formation of the skeletal system. Other components that are also contained in cottage cheese have a beneficial effect on the body in diseases of the heart, kidneys, hypertension, atherosclerosis. The composition of the curd protein includes the amino acid "Methionine", which acts prophylactically, protecting the liver from obesity.

Once in the human body, cottage cheese protein is broken down into amino acids, which are so necessary for the proper functioning of organs and tissues. It is valued by athletes as a product that promotes muscle growth. Regular consumption of cottage cheese has a positive effect on vision and increases protective functions immunity. It is used as a component in the diets of many diets.

The composition of cottage cheese contains a complex protein casein, it has a lipotropic effect, contributing to the normalization of fat metabolism and lowering cholesterol levels in the blood.

Cottage cheese is of great benefit for expectant mothers: it saturates the body with vitamins and calcium, which the mother gives to her child. Pregnant women just need to eat cottage cheese, because its use has a positive effect on the development of the fetus.

Vitamins and Minerals:

According to research, 100 grams of homemade cottage cheese contains:

Calories: 160 calories per 100 grams

• Glycemic index (GI) homemade cottage cheese = 30
• Proteins - 18 g
  
• Fats - 9 g
  
• Carbohydrates - 3 g
  
• Water - 67.8 g
  
• Organic acids - 1.2 g
  
• Ash - 1 g
  

Vitamins:

• Vitamin A (Retinol) - 0.05 mg
  
• Vitamin B1 (Thiamin) - 0.04 mg
  
• Vitamin B2 (Riboflavin) - 0.27 mg
  
• Vitamin B4 (Choline) - 46.7 mg
  
• Vitamin B5 (Pantothenic acid) - 0.28 mg
  
• Vitamin B6 (Pyridoxine) - 0.11 mg
  
• Vitamin B9 (Folic Acid) 35 mcg
  
• Vitamin B12 (Cobalamin) - 1 mcg
  
• Vitamin C (Ascorbic acid) - 0.5 mg
  
• Vitamin D (Calciferol) - 0.29 mcg
  
• Vitamin E (Alpha tocopherol, TE) - 0.2 mg
  
• Vitamin H (Biotin) - 5.1 mcg
  
• Vitamin PP - 3.9 mg
  
• Niacin - 0.4 mg
  

Macronutrients:

• Potassium - 112 mg
  
• Calcium - 164 mg
  
• Magnesium - 23 mg
  
• Sodium - 41 mg
  
• Sulfur - 180 mg
  
• Phosphorus - 220 mg
  
• Chlorine - 152 mg
  

Trace elements:

• Iron - 0.4 mg
  
• Cobalt - 1 mcg
  
• Manganese - 0.008 mg
  
• Copper - 74 mcg
  
• Molybdenum - 7.7 mcg
  
• Selenium - 30 mcg
  
• Fluorine - 32 mcg
  
• Zinc - 0.394 mg

Negative properties of cottage cheese:

Cottage cheese has practically no contraindications. Harm can occur with individual intolerance or with the use of a stale product. Individual intolerance may be associated with the inability to digest lactose, which is present in dairy products. in this case, a person expects diarrhea, bloating. A similar reaction when using cottage cheese can occur in an absolutely healthy person, whose body normally metabolizes lactose. This is due to the staleness of the product, since such cottage cheese is a favorable environment for the reproduction of bacteria.

Curd contains saturated fatty acids. Frequent consumption of fatty cottage cheese with a coefficient of 18 - 20% will contribute to the development of early atherosclerosis.

Excessive abuse of cottage cheese can lead to kidney overload, as it contains a large amount of protein. In some cases, it can cause an allergic reaction in the form of skin rashes.

How to choose healthy cottage cheese?

Composition of cottage cheese: fresh milk, sourdough, rennet and calcium chloride, other ingredients are not allowed. Cottage cheese, which contains vegetable fats, various stabilizers, flavors, flavor enhancers, is no longer curd, now it is called "Curd product". Usually such goods are sold in stores, in various packages that promise only benefits and a shelf life of 6-7 days.

Natural cottage cheese is stored in the refrigerator, provided that it is in a closed container, no more than 3 days from the date of its manufacture. Then microorganisms can begin to develop in it. Fresh cottage cheese should have a pleasant, sour-milk smell and taste, even color, without spots.

You can get acquainted with the calorie content of dairy products in the Table of calorie content of dairy products.

Personally, I prefer market cottage cheese. In the market, the chances of buying a natural product increase. As for the dangers that may lie in wait when buying on the market, I personally have not met them, I buy from a seller who has not only been verified by me. Of course, it is up to you to choose which cottage cheese to purchase.

I advise you to add this most useful product to your diet. It is best to consume it at the last meal, before going to bed. Eat more than 150g. no need. While you sleep, the cottage cheese will slowly feed the body with protein, which will keep the muscles from breaking down.

cottage cheese rich in vitamins and minerals such as: vitamin B2 - 14.4%, vitamin PP - 19.5%, calcium - 16.4%, phosphorus - 27.5%

What is useful cottage cheese

• Vitamin B2 participates in redox reactions, increases the susceptibility of color by the visual analyzer and dark adaptation. Inadequate intake of vitamin B2 is accompanied by a violation of the condition of the skin, mucous membranes, impaired light and twilight vision.
• Vitamin PP participates in redox reactions of energy metabolism. Inadequate vitamin intake is accompanied by a violation of the normal state of the skin, gastrointestinal tract and nervous system.
• Calcium is the main component of our bones, acts as a regulator of the nervous system, is involved in muscle contraction. Calcium deficiency leads to demineralization of the spine, pelvic bones and lower extremities, increases the risk of osteoporosis.
• Phosphorus takes part in many physiological processes, including energy metabolism, regulates acid-base balance, is part of phospholipids, nucleotides and nucleic acids, is necessary for the mineralization of bones and teeth. Deficiency leads to anorexia, anemia, rickets.

The complete guide to the most useful products you can see in the app

According to the method of coagulation of milk proteins, cottage cheese is divided into acid and acid-rennet. Sour curd is usually made from skimmed milk. In this case, the protein coagulates under the action of lactic acid, which is formed in the process of lactic acid fermentation, which develops as a result of the introduction of starter cultures into milk.

Acid-rennet curd differs from acid curd in that when it is produced, rennet is used simultaneously to coagulate milk proteins (or) and starter cultures of lactic acid bacteria.

The words "cottage cheese" and "cheese" in Russian are separated. In Old Russian, Ukrainian, Serbian and some other Slavic languages, the word "syr" means both cheese itself and cottage cheese, so for quite a long time everything that was made from cottage cheese was called "cheese" (for example,).

cottage cheese is "complete" and contains all the essential. The degree of digestibility of cottage cheese protein by the human body is slightly higher than protein, which makes cottage cheese popular in bodybuilding, especially among vegan and vegan bodybuilders

Compound

The composition of cottage cheese is truly healing! It, like milk, contains a milk protein called casein. It has nutritional value and perfectly replaces animal proteins. Only 300 g of this product fully satisfies the body's daily protein requirement. Delicious cottage cheese rich in minerals that strengthen bone tissue well. This product also contains amino acids that prevent kidney disease, as well as B vitamins that prevent the development of atherosclerosis. Cottage cheese calories may vary depending on fat content.

Beneficial features

Like milk and sour cream, cottage cheese, thanks to the minerals it contains and a large amount of calcium, helps to strengthen bone tissue, improves the functioning of the nervous system, and has a positive effect on the metabolic process as a whole. Cottage cheese contains large amounts of proteins, calcium salts, milk fats, phosphorus salts (moreover, curd proteins are digested much more gently) and lipotropic substances that promote the dissolution of fat in cells, which, in particular, prevents the development of cellulite.

Unlike other dairy products, natural country cottage cheese contains high-grade proteins and a small amount of fat at the same time, which allows the body to be satiated, and at the same time benefit from this product. After all, cottage cheese is one of the few dairy products that does not have any contraindications. The use of cottage cheese is useful for liver diseases, hypertension, stomach ulcers, atherosclerosis, pathologies of the pancreas and gallbladder, and intestinal diseases.

Cottage cheese indispensable as a permanent component of baby food, largely due to the amino acid it contains - methionine. And together with tryptophan, another amino acid, methionine incottage cheese helps to maintain the functions of the respiratory, hematopoietic, digestive and nervous systems. Also cottage cheeserich in choline and lecithin. It is believed that cottage cheese contains the optimal combination of phosphorus and potassium, sodium and potassium compounds.

And all these useful substances are contained primarily in natural, freshly prepared cottage cheese, obtained in a natural way, because in store-bought cottage cheese, which has gone through more than one stage of special industrial processing, useful substances are destroyed, remaining in a small amount. Country cottage cheese prepared in ecologically favorable conditions from fresh milkand taste, and smell, and even appearance, not to mention the benefits, are completely different.

High-quality cottage cheese is the key to good health!

Production

It is known that people have learned to docottage cheese even in ancient times. One of the versions of the appearance of this environmentally friendly fermented milk product is considered to be chance. It is possible that our ancestors once simply turned sour ordinary cow's milk, and the resulting whey was also accidentally glass. The remaining loose (although it could have been dense) mass turned out to be not just edible, but very tasty and healthy. This was the curd. In ancient times, milk was also curdled with the help of the rennet of animals that were available in the household.

In pre-Petrine Russia, the preparation of cottage cheese was a common element of housekeeping. It was also called cheese, sour cheese. Hence the confusion in the names "syrniki" and "cottage cheese". And only at the end of the 19th century, cottage cheese began to be produced industrially.

Manufacturing

The production process for making cottage cheese looks like this: milk is normalized (the desired fat content is set), pasteurized and poured into baths. The baths maintain a certain temperature, which is necessary for the normal course of processes. Ferment and pepsin are added to warm milk. After some time, a curd grain is formed in the bath, which forms a monolith (milk proteins coagulate and precipitate, forming a sticky mass). At the same time, curd begins to stand out. - transparent yellowish liquid - a by-product of production. At the final stage, the curd monolith is cut with strings into small pieces in order to increase the surface area and facilitate the outflow of whey. Next, the curd grain is squeezed and cooled. At the end of the technological process, the curd is packaged.

T. F. Efremova New dictionary of the Russian language. Explanatory derivational -M.: Russian language, 2000. - T. II. (P-Z). - 1088 p. - 5000 copies - .

CHEMICAL COMPOSITION OF COTTAGE CHEESE

First of all, cottage cheese contains, as already reported, protein. It also contains minerals, lactose (milk sugar), fat, enzymes, hormones, vitamins, carbon dioxide.

In total, cottage cheese contains 12 vitamins. These are vitamins of groups A, D, B, C. Also, cottage cheese contains a large amount of calcium, iron, and phosphorus. The most remarkable thing is that all these substances are in the curd in a perfectly balanced state and in a more concentrated form than, for example, in milk. From 500 g of milk, about 200 g of cottage cheese is obtained, respectively, the value of cottage cheese is much higher than that of milk.

PROTEINS

What is, for example, that protein, the value of which we have repeatedly mentioned in cottage cheese? Proteins are macromolecular substances twisted into chains consisting of hundreds of amino acid residues. Enzymes, which are also found in cottage cheese, also belong to proteins. They accelerate biochemical reactions in the body, and each of them performs a strictly defined function.

Proteins are very important substances. They must be in the human body in the correct proportions. Protein deficiency leads to anemia, anemia, diseases of internal organs, in particular, the liver, pancreas, various skin inflammations, diarrhea, weight loss, fatigue, and reduced resistance to infections.

But it is also important not to oversaturate the body with excessive consumption of protein foods. This gives a very large load on the liver, kidneys - those organs that are responsible for removing toxins from the body. After all, excess proteins do not accumulate in the body, as happens, for example, with fats. Therefore, the supply of proteins must be constantly replenished.

Curd contains amino acids. It should be noted that some types of amino acids are not produced independently by the human body, they should only be supplied with food.

These amino acids are: tryptophan, lysine, methionine. These amino acids, which are indispensable, are responsible for limiting the absorption of food, their deficiency leads to a limitation in the absorption of other amino acids by the human body. Valine: This amino acid is involved in the synthesis of hemoglobin. Lycine, isolicin, threonine, which are also essential amino acids; phenylalanine - its lack and improper metabolism can lead to dementia; and finally, histidine, which is responsible for the growth and development of the child.

FATS

The content of easily digestible milk fat in cottage cheese is also very important in human nutrition, since the possibilities for the accumulation and synthesis of fat by the human body are very limited. Fats are divided into protoplasmic and reserve. Those that are part of the cells are called protoplasmic, those that accumulate as a result of food consumption are called reserve.

Fats are processed in the small intestine with the help of a special enzyme: lipase. This enzyme is activated only in combination with bile produced by the pancreas. So when you, dear reader, eat fatty pork, beef, lamb, and even more fat, you put a very big load on your liver and pancreas.

Of course, if these organs are in a satisfactory condition, then you can sometimes make them work. However, if there are certain functional disorders in their work, the fat contained in these meat products can cause irreparable harm to your health.

What to do in this case? After all, it is impossible to completely abandon animal fats, their lack is also detrimental to human health? This is where it will look natural to turn to animal fats found in dairy products. The highest concentration of milk fat in cheeses, sour cream and, of course, cottage cheese. The transition to milk fats is especially important for people with liver diseases: cirrhosis, hepatitis.

In dairy products, in particular cottage cheese, as already mentioned, there is methionine - an essential acid with a lipotropic effect, that is, it helps to reduce the accumulation of fat in the liver. This amino acid is part of the phosphatides - substances involved in the metabolism of fats in the body. It should be noted here that fatty liver can lead to cirrhosis, so it is very important to prevent this by eating dairy fats whenever possible.

CARBOHYDRATES

Many products can serve as a source of carbohydrates: flour and all products from it, such as bread, muffins, buns, pies, cakes; rice and rice flour; buckwheat; semolina and many others.

The group of carbohydrates includes: polysaccharides glycogen and starch, disaccharides sucrose and milk sugar, monosaccharides fructose, glucose, galactose. What benefits do carbohydrates bring to our body, why are they so important? First and foremost, carbohydrates serve as a source of energy. With all that, they are quickly consumed by the body, so their constant replenishment is required. But an excess of carbohydrates is not very good for human health.

As a result of this, diseases such as hyperglycemia, obesity, diabetes mellitus can occur.

Cottage cheese as a source of carbohydrates may not seem like a very valuable product, but this is only at first glance. It contains only a small amount of galactose and milk sugar, but this is its advantage, not a disadvantage, since in therapeutic diet for patients with diabetes, for example, it will be the number one product.

Carbohydrates are processed in our body with the help of the pancreas, which produces a special hormone called insulin. In diabetes, the work of the pancreas is disrupted, as a result of which glucose begins to flow directly into the blood. For people suffering from this disease, it is very important to follow a diet that contains a large amount of consumed easily digestible proteins and fats, and at the same time a very small amount of carbohydrates. Cottage cheese completely fits these parameters, since proteins, as we have already said, are completely digestible in it, and are contained in a half-split state (pepsinization), fats are absorbed by 98%, and carbohydrates of exactly the type that will not harm the diseased organ - pancreas.

Some mild forms of diabetes (such as gestational diabetes) can be treated almost entirely with a diet that leading role given to lactic acid products. Due to their composition, they give rest to the secretory apparatus of the pancreas.

MINERALS

Minerals that a person receives with food are very important for his life. As for cottage cheese, it contains, of course, first of all calcium, iron, then magnesium, phosphorus and some others, but their amount is not so great.

Calcium is the most important building material of the human skeleton. Suffice it to say that in combination with phosphates and fluorides, calcium makes up 98% of bone tissue and teeth. Lack of calcium can cause diseases such as rickets, osteoporosis, osteomalacia. As can be seen from the names, these diseases are associated with disorders of the musculoskeletal system. Calcium is also involved in the excitability of the nervous system and muscle contraction, in enzyme metabolism.

Do you see how important calcium is for the growth and health of your body? But the most important source of calcium is cottage cheese. A healthy adult is recommended to consume only 200 g of cottage cheese per day, and the daily need for calcium will be satisfied. This is very little, if we consider that, for example, more than half a liter of milk would have to be drunk for this purpose. Cottage cheese, as it were, concentrates all the amount of calcium that is present in the first source product - milk.

However, as we have already said, for the production of bone tissue, calcium combines with another mineral, which is also found in excess in cottage cheese - phosphorus. Phosphorus is very important for the created bone system to be at the proper level, it is actively involved in the structure of bone tissue and the prevention of its destruction.

There is a lot of iron in cottage cheese compared to milk. Is it worth saying that such a microelement as iron is extremely important for the human body? The amount of iron determines the level of hemoglobin in the blood, or rather, the amount of red blood cells in the blood. A person who does not receive a certain amount of iron from food can get sick with various forms of anemia, and this disease is very dangerous, especially for a growing organism. Thus, the presence of these substances in cottage cheese allows us to strongly recommend it in baby food, as well as in the nutrition of pregnant and lactating mothers.

VITAMINS

Vitamins belong to the category of substances that scientists had no idea about for a long time. It was believed that for normal life, a person needs only fats, proteins and carbohydrates. However, light on the existence of some other substances necessary for the human body was shed by one experiment carried out in 1881 by the Russian scientist N. N. Lunin.

In an effort to find out what underlies rational nutrition, he began to feed several experimental animals only sterilized food - completely pure proteins, fats and carbohydrates obtained from milk. In addition to this artificial food, he gave the animals water and mineral supplements. It would seem that the animals received everything that was only considered necessary for nutrition at that time, but they fell ill, gradually weakened, and eventually died. However, it is interesting that if the animals, along with such artificial food, were given natural milk, they remained completely healthy, moreover, they gave the impression of well-groomed and full of vitality.

The results of this study shed some light on such a terrible disease as scurvy, but it was not until 1910 that vitamins were discovered.

Sources of vitamins are both vegetable and animal foods. However, we are now talking about one of the dairy products - cottage cheese, and as you just learned, natural milk alone helped replace the entire complex of vitamins in the diet of animals receiving artificial food. This means that the composition and ratio of vitamins in cottage cheese - a concentrated dairy product - is ideal.

Vitamins are organic substances that regulate the metabolism in the human body. They come mainly with food and are not produced by the internal organs and glands themselves. With a lack of any group of vitamins, beriberi occurs - a serious disease that lowers a person's immunity, makes him susceptible to disease, and is expressed by general fatigue and weakness. With this disease, all body systems are loosened, including the circulatory, gastrointestinal, and nervous systems. Therefore, it is so important that a person receives all the necessary vitamins with food. There are as many as 12 of them in cottage cheese, and these are vitamins of groups A, B, C, D and many others.

Vitamin A affects the development of growth, vision, the condition of the skin and mucous membranes. Lack of it in nutrition can lead to the so-called "night blindness" - weakening of vision at dusk. Vitamin A is also very important for a growing body. Therefore, cottage cheese must be included in the diet of the child. In fact, in our country high level the supply of children with dairy products has been supplied - from the age of three months the baby begins to receive cottage cheese and milk from the children's kitchen. Thus, cottage cheese is the first complementary food for a child - an acquaintance with food other than mother's milk.

Vitamin C, found in cottage cheese, is also very important for human life. Recall that a lack of this vitamin alone can lead to scurvy, which we have already mentioned - a disease when the mucous membranes become inflamed, teeth loosen and fall out, joints swell, general weakness and weight loss are observed, and if this vitamin is not supplied to the body in time, death is possible.

B vitamins are also found in cottage cheese. Vitamin B1 is involved in the metabolism of carbohydrates, its content in cottage cheese is not very high. Vitamin B1 helps in the oxidation of glucose. Since the content of milk sugar in cottage cheese is small, this helps to limit it to such a small amount. In general, the lack of this vitamin leads to multiple inflammation of the nerve trunks (food polyneuritis), tissue metabolism disorders, and muscle weakness.

Vitamin B2 is needed for the normal metabolism of proteins and carbohydrates, it is very important for the proper growth of the body, wound healing. It is responsible for tissue respiration and energy production. Needless to say, a growing child's body needs cottage cheese, in which it is found in large quantities. The lack of this vitamin is expressed in peeling of the skin, irritation of the mucous membranes of the eyes, affects visual acuity.

Vitamin B12 plays a very important role in the process of hematopoiesis. With its deficiency, anemia can develop.

Nicotinic acid (vitamin PP) is involved in the composition of enzymes that produce oxidative processes in the body. The amino acid tryptophan, found in cottage cheese, is synthesized by our body into this acid. Its deficiency leads to weakness, insomnia, fatigue, and inflammation of the skin (pellagra).

We should especially talk about vitamin D, which, although not found in cottage cheese, can be produced by the human body under the influence of sunlight from provitamins, which cottage cheese is rich in. Vitamin D is essential for the growth of the human body, and especially the body of a child. It participates in the exchange of calcium and phosphorus, which is present in sufficient quantities in cottage cheese, and is responsible for the growth of the child, as well as for the condition of bones and teeth. If the child's body is deprived of this vitamin, then this leads to a general weakening of the bone apparatus, its deformation. This disease is called rickets. Also, without this vitamin, immunity to many diseases decreases.

Having considered the composition of such a useful product in all respects as cottage cheese, we can recommend its use to both healthy and sick people. Now there are practically no diseases in which cottage cheese would be contraindicated. One can only make a definite choice in favor of fatty or fat-free cottage cheese, fresh or sour. It is very useful for healthy people to use cottage cheese as a prophylaxis against various diseases, and simply as a tasty and nutritious food product.

Determination of impurities

Foreign impurities added to adulterate milk can be detected by special methods. So, soda in milk is determined using an alcoholic solution of rosolic acid. Milk containing soda, when added to this acid, turns pink-red. An admixture of starch can be detected by the reaction of milk with an iodine solution (Lugol's solution). Adding this solution to a small amount of test milk in a test tube produces a blue color.

The following reactions are put on the presence of preservatives added to milk to prevent souring. Hydrogen peroxide is determined by reaction with a 1% sulfuric acid solution of vanadic acid. Milk turns red in the presence of hydrogen peroxide. In the presence of formaldehyde, the layering of milk on a special reagent (concentrated sulfuric acid with a few drops of nitric acid added to it) leads to the formation of a purple or faint yellow-brown ring at the fusion boundary.

The falsification of milk and other products is an extremely rare occurrence in our reality, but in some cases it can still take place. The falsification of milk reduces not only its nutritional value, but also its biological value (reduces the content of protein and fat) and is extremely dangerous in epidemiological terms. So, for example, the addition of soda, reducing the acidity of milk, contributes to the destruction of vitamin C and the growth of putrefactive microflora, including pathogenic ones. Under normal conditions, an increase in acidity is due to the growth of lactic acid bacteria, which inhibit the growth of extraneous, mainly putrefactive, microflora. When falsifying milk with contaminated water or with foreign impurities, in addition, microorganisms - causative agents of intestinal infections. Getting into milk, they find favorable conditions for their development and, multiplying, cause an outbreak of an infectious disease.

Due to the fact that cases of milk falsification are most often possible in the markets, veterinary and sanitary examination laboratories are now working there. In them, milk that goes on sale from individuals, collective farms, etc., is subjected to the simplest laboratory studies: organoleptic properties, relative density, acidity, fat content, and dry residue are determined according to the formula. Individuals, collective farms and state farms must also submit certificates from the veterinary supervision authorities on the state of animal health to milk control stations. After that, a permit for the sale of milk is issued.

Poor quality or adulterated milk is rejected. In this case, the milk is denatured by adding bright dyes (beetroot juice, etc.) so that it is not sold.

reaction to starch

Dishes and reagents: 1) test tube; 2) 10 ml cylindrical pipette; 3) Lugol's reagent.

Definition progress. Pour 5 ml of milk into a test tube, add 2-3 drops of Lugol's reagent and mix. In the presence of starch, blue coloration of milk occurs.

A source: Okorokova Yu.I., Eremin Yu.N. Food hygiene - 3rd ed. - M. Medicine, 1981

Starch - and , which is alpha . Starch formula:(C 6 H 10 O 5 )n. Starch, synthesized by various plants in chloroplasts, under the action of at , differs somewhat in the structure of grains, the degree of polymerization of molecules, the structure of polymer chains, and physicochemical properties.

Physical and chemical properties

Tasteless, amorphous powder , insoluble in cold water. Under the microscope, you can see that it is a granular powder; when compressing the starch powder in the hand, it emits a characteristic "squeak" caused by the friction of the particles.

V hot water swells (dissolves) solution - ; with solution forms a blue inclusion compound. In water, with the addition of acids (diluted H 2 SO 4 etc.) how , gradually with a decrease in molecular weight, with the formation of the so-called. "soluble starch", dextrins, up to .

Starch molecules are heterogeneous in size. Starch is a mixture of linear and branched macromolecules.

Under action or heated with acids undergoes hydrolysis. Equation:(C 6 H 10 O 5 )n + nH 2 O-H 2 SO 4 → nC 6 H 12 O 6 .

Qualitative reactions:

Starch, unlike glucose, does not ;

Like sucrose, it does not reduce copper (II) hydroxide;

Interacts with iodine (staining blue).

Being a polyhydric alcohol, starch forms ethers and esters. A characteristic qualitative reaction to starch is its reaction with iodine ( starch iodine reaction ):

When iodine reacts with starch, enable connection (clathrate) channel type. Clathrate is a complex compound in which particles of one substance (“guest molecules”) are introduced into the crystal structure of “host molecules”. Amylose molecules act as "host molecules", and iodine molecules act as "guests". Iodine molecules are located in the channel of a spiral with a diameter of  1 nm, created by an amylose molecule, in the form of chains Getting into the helix, iodine molecules are strongly influenced by their environment (OH groups), as a result of which the I–I bond length increases to 0.306 nm (in the iodine molecule, the bond length is 0.267 nm). Moreover, this length is the same for all iodine atoms in the chain. This process is accompanied by a change in the brown color of iodine to blue-violet ( max 620–680 nm). Amylopectin, unlike amylose, gives a red-violet color with iodine ( max 520–555 nm).

Dextrins formed during the heat treatment of starch, acid or enzymatic hydrolysis, also react with iodine. However, the color of the complex is highly dependent on the molar mass of the polymer (see Fig. table).

Low molecular weight dextrins begin to show external signs of reactions of the aldehyde form of glucose, because as the polymer chain decreases, the proportion of reducing terminal glucose residues increases.

Table - Color reactions of dextrins with iodine

Dextrin (C 6 H 10 O 5) k

Degree of polymerization k

Staining of the complex with iodine

Amylodextrins

Blue or purple

Erythrodextrins

25–29

Red

Ochrodextrins

21–24

tan

Maltodextrins

Lack of response

1 2 3

Figure - Starch grains from various natural sources under a microscope ( 1 - from potatoes,

2 - from corn, 3 - from wheat)

Starch is widely distributed in plants and is a reserve source of energy for them. It is mainly found in tubers, seeds and roots in the form of grains. Depending on the plant, grain (see. drawing) differ in shape and size (average 0.002–0.15 mm). The largest grains are potato starch. In cereals, the starch content reaches  70% (in rice grains up to 80%), in potatoes  20%. The main raw materials for starch are potatoes and corn.

Starch is used as a food product, a component of medicines and for starching linen. It is used to obtain molasses, glucose and ethyl alcohol, as well as in analytical chemistry to detect iodine.

L.A. Yakovishin

Questions

1) Proteins are ...

2) For the qualitative detection of a protein in a natural object, the following reaction can be used:

- “silver mirror”

- "Wagner"

biuret

Any of the above

3) A qualitative reaction to a protein is its interaction with

1) freshly precipitated copper (II) hydroxide
2) copper (II) sulfate
3) sodium hydroxide
4) nitric acid

3)XANTHOPROTEIN , color qualities. district on add conc. HNO 3 3 .

4) Why does the interaction of starch and iodine produce a blue color: when they are heated, the solution becomes colorless, when cooled, it reappears?

5) What compounds are the structural units of protein molecules? Give them a description and give their examples in the form of structural formulas.

6) Describe the chemical composition, structure and properties of proteins.

7) What biological functions do proteins perform in the body?

8) What chemical bond is called a peptide? Write the reaction for the formation of a dipeptide.

9). Fill in the table "Classification of proteins"

Type of squirrel

Protein composition

1. proteins -

……………. -

………….

have a non-protein part (complex protein)

2. …………. -

defective -

The whole range of amino acids

…………….

10) Complete the sentence, insert the missing words:

………… the Fischer-Danilevsky theory represents a protein molecule as a long chain of ……… ……… connected ………. connections.

alanine

serine

….

polypeptide

11) Fill in the tables:

1) "Types of protein structure"

Structure name

What is

What connections are supported

1. primary

linear circuit

peptide

2. ……………

……………….

……………….

3. ……………

……………….

……………….

4. ……………

……………….

……………….

2) " Chemical properties proteins"

Property

Process essence

Causes

1. Hydrolysis

Breakdown of protein into individual amino acids

The action of enzymes

2. ………….

Oxidation on heating

Heat

3. …………

…………………

1) ………….

2) ………….

3) ………….

4) ………….

12) Carry out "color reactions" on proteins ( laboratory work).

Experience 1. Take a clean test tube, pour 1 ml of chicken protein solution into it, add 0.5 ml of concentrated nitric acid (carefully!). What are you watching?

Experience 2. Pour 1 ml of copper sulfate solution into a clean test tube, add sodium hydroxide solution until a blue precipitate forms. Then add 1 ml of protein solution. What are you watching?

Enter the results of observations in the table

Name of the reaction

Reagents used

Observations

1.xantoprotein

……………….

……………….

2. biuret

……………….

……………….

Answers:

1) Proteins (polypeptides) - biopolymers built from residues
-amino acids connected peptide(amide) bonds.

2) 2) Biuret reaction, color reaction to , which is carried out by adding a dilute aqueous solution to the alkaline solution of the latter Cu 2+ (usually CuSO 4). In this case, the solution turns into an intense purple color due to the formation of a complex Comm. (formula I, M + - alkali metal cation). In a reaction similar to biuret, many substances enter, containing at least two amide groups, aminohydroxyethylene group -CH(NH 2)CH(OH)-, amides and imides and some other connections. The reaction products in this case are purple or blue in color. In conditions biuret reaction give a violet color, which was used for their qualitative and quantitative analysis.

Lit.: Carrer P., Course . For its implementation to the solution add conc. HNO 3 until the formation of sediment stops, to-ry when heated. dyed yellow. The coloration results from 3 due to xantoprotein .

5-8)

Formally, the formation of a protein macromolecule can be represented as a polycondensation reaction of -amino acids:

When two molecules interact -amino acids, a reaction occurs between the amino group of one molecule and the carboxyl group of another. This leads to the formationdipeptide ( ).

From three molecules of -amino acids (glycine + alanine + glycine) a tripeptide is formed:

H 2 N-CH 2 CO-NH-CH (CH 3) -CO-NH-CH 2 COOH

Similarly, the formation of tetra-, penta- and polypeptides occurs.

The molecular weights of various proteins (polypeptides) range from 10,000 to several million. Protein macromolecules have a stereoregular structure, which is extremely important for their manifestation of certain biological properties.
Despite the abundance of proteins, they contain residues of only 22 -amino acids.

The functions of proteins in nature are universal:

catalytic (enzymes);

regulatory (hormones);

structural (wool keratin, silk fibroin, collagen);

motor (actin, myosin);

transport (hemoglobin);

spare (casein, egg albumin);

protective (immunoglobulins), etc.

The various functions of proteins are determined -amino acid composition and structure of their highly organized macromolecules.

Allocate 4 levels structural organization proteins.

Primary Structure- certain sequence  -amino acid residues in the polypeptide chain.

secondary structure- the conformation of the polypeptide chain, fixed by many hydrogen bonds between N-H groups and C=O. One of the secondary structure models is  -spiral.

Tertiary structure- the form of a twisted spiral in space, formed mainly due to disulfide bridges -S-S-, hydrogen bonds, hydrophobic and ionic interactions.

Quaternary structure- aggregates of several protein macromolecules (protein complexes) formed due to the interaction of different polypeptide chains.

Which natural polymers have a branched structure of macromolecules:

a) amylose;

d) nucleic acids;

b) amylopectin;

e) natural rubber;

c) proteins;

g) cellulose?

Cottage cheese is a fermented milk product that is extremely beneficial for the human body. It contains in its composition all the essential amino acids and is able to be absorbed much better than meat. It can be consumed salty, mixed with sour cream, milk, berries, cream, honey, condensed milk and even wine. Cottage cheese is well suited for baking and stuffing for pies. Curd mass made from cottage cheese with chocolate, candied fruit, fruits or various nuts is a tasty and nutritious dessert, and low-fat cottage cheese with greens, yogurt or vegetables is a dietary breakfast. However, most people who eat this valuable product only partially know the chemical composition of cottage cheese, and meanwhile it is very rich in various vitamins and microelements.

The chemical composition of cottage cheese

100 grams of cottage cheese contains:

• Fat - 9 gr,
• Proteins - 16.7 gr,
• Carbohydrates - 2 gr,
• Vitamin A - 80 mcg,
• Vitamin PP - 3.1722 mg,
• Vitamin C - 0.5 mg,
• Vitamin B1 - 0.04 mg,
• Vitamin B2 - 0.3 mg,
• Phosphorus - 220 mg,
• Sodium - 41 mg,
• Potassium 112 -mg,
• Calcium - 164 mg,
• Magnesium - 23 mg
• Iron - 0.4 mg
• Calorie content of the product - 155.3 kcal.

The benefits of cottage cheese

Cottage cheese is necessary for the restoration and growth of all tissues of the human body, especially bone. It strengthens nails, hair, teeth, heart muscle, and is useful for the optimal functioning of the nervous system. Also, cottage cheese contains tryptophan and the amino acids methionine, which are involved in the process of blood formation, and this product is included in dietary nutrition for diseases of the heart, liver, gastrointestinal tract, gallbladder, and more.

Digestibility of cottage cheese

The main advantage of cottage cheese is its ability to be easily and quickly digested. Scientists have proven that the proteins obtained from it enter the tissues faster than the proteins from meat, milk and fish. Moreover, fatty cottage cheese, the composition of which contains more protein and is absorbed faster than dietary. However, it has more fat, and for those who are overweight, it is better to eat fat-free cottage cheese. If you use it even at night, it does not add extra pounds. It is worth noting that it is better to prefer home-made cottage cheese, which can be made at home, as it is much healthier.

It is used in many diets, used in cosmetology for the purpose of rejuvenation, contains a storehouse of useful vitamins and minerals that affect the internal functions of the body.

What is cottage cheese made of?

Most of all in cottage cheese protein and calcium. Protein is the basis of life, calcium is the basis of bone tissue.

The composition of the product varies depending on the type of raw material used in production and the fat content.

In 100 gr. cottage cheese contains:

• 15 gr. squirrel;
• 18 gr. fats;
• 2.9 gr. carbohydrates;
• more than 50 gr. water.

In bold cottage cheese there is more protein (18 grams), but less fat, and in fat-free cottage cheese there is a lot of water and practically no fat, but there is more than 20 grams of protein.

Cottage cheese contains vitamins B, H, C, E, and PP, as well as vitamin A. Among the minerals are: iron, phosphorus, choline, zinc, sodium, chlorine, calcium, potassium, magnesium, fluorine, selenium, copper, cobalt and manganese. Almost all of them are well absorbed by the body.

Useful properties of cottage cheese

The protein contained in the product can replace the vegetable, so it is suitable for full growth muscle mass. Those who constantly eat cottage cheese reduce the risk of atherosclerosis by several times, it contributes to the overall strengthening of the nervous system, and supplies calcium to the bones. The product is very popular with bodybuilders - they eat it every day.

Nutritionists urge to "include" cottage cheese in the diet for diseases of the liver and gallbladder, pancreatitis, gastritis, hypertension, duodenal ulcer and stomach.

Many doctors advise parents to "include" cottage cheese in the diet of children. Calcium and phosphate salts, which are in the composition, have a positive effect on the body, help strengthen tooth enamel, the proper development of bone tissue and enhance the body's immune forces.

The milk protein present in cottage cheese promotes the formation of new cells in the child's body, so children should eat this product regularly.

Daily consumption of cottage cheese improves metabolism in the body. It is well known that this product is indispensable for pregnant and lactating mothers. Elderly people also need it. In addition, everyone who has problems with the gastrointestinal tract, central nervous system and metabolic disorders: indigestion, constipation, and so on.

Curd contains antibacterial substances. They normalize the microflora, and lactic acid bacteria promote the absorption of calcium and phosphorus, the production of vitamin B.

Application in cosmetology

Cottage cheese can be used not only for food, it is effectively used in cosmetology. There it is used as anti-aging and nourishing masks for the whole body, face and neck. Beauty recipes based on cottage cheese have been known since ancient times, from where they came to the modern world.

Any woman can use cottage cheese, no matter what type of skin she has. It slows down the aging process and allows you to stay beautiful a little longer. Many people know about this and at home they prepare softening and regenerating masks that really give results.

How to prepare a mask?

If you have dry or normal skin, you can use a cottage cheese and sour cream mask every day. It is superimposed for twenty minutes. The mask helps to eliminate pigmentation.

For oily skin

Take two spoons of cottage cheese, mix with serum and apply on face. Hold for fifteen minutes, then rinse with green brewed tea.

If the skin lacks vitamins, use this recipe: mix cottage cheese, kiwi, black tea and olive oil. Apply the mask on your face, wait about fifteen minutes, then rinse with warm water.

A mixture of kefir, lemon juice and cottage cheese will help to give the face freshness and a healthy color.

A mixture of sour cream, cottage cheese and sea salt will help rejuvenate your face.

calories

The calorie content of cottage cheese depends on the fat content. In fatty curd 230 kcal per 100 gr. product, in bold 135-160 kcal. Least of all calories in a low-fat product - 90-105 kcal, it is also recommended for those who want to reduce weight.

There is also granular cottage cheese, it is stored a little longer, and in 100 gr. The product contains 150 kcal.

Fat-free cottage cheese is easily digestible with almost any food, and its low content of fats and carbohydrates is a good opportunity to use the product as a diet food. You can “sit” all day on cottage cheese once a week, and such a diet can be alternated with others.

However, with the frequent use of fat-free cottage cheese, health problems can begin. Hair and skin are the first to be affected.

How to choose cottage cheese?

A frequent problem is the purchase of expired or low-quality cottage cheese. Before buying, carefully inspect the packaging. It should be free of worn traces of paint, it should be solid, and the production and expiration dates should be clearly visible.

Cottage cheese should not have a strongly pronounced sour smell.

Compound

The composition of the curd should be as follows:

• cream;
• milk;
• calcium chloride;
• leaven;
• rennet enzymes.

Also give preference to packages that indicate GOST, not TU. In this case, the likelihood of counterfeit goods is less.

What if I buy cottage cheese by weight?

Try to buy cottage cheese in the shop where you bought it before and you liked its taste.

So remember some rules:

• the color of the product is white-cream, without a bluish tint;
• if there is an opportunity to taste the cottage cheese (you were allowed) - do it. It should not be very sour, and the smell should be pleasant;
• consistency - homogeneous;
• a yellow tint indicates that flour or sugar has been added to the curd.

How to store cottage cheese?