How to check natural milk or not. How to distinguish real milk from a fake? Starch and other impurities in milk and dairy products

RESEARCH WORK ON HEALTHY NUTRITION

"Determining the quality of milk at home"


INTRODUCTION

Milk is one of the most important human food products. In its composition, the most necessary substances for human health were found. Fats and carbohydrates are sources of energy. Proteins contain all the necessary amino acids, including those that are not synthesized by the human body.

Minerals contained in milk contribute to the formation and absorption of vitamins, are part of human tissues. Milk contains all known vitamins.

The exclusion of milk from the diet can lead to a decrease in the necessary substances in the body.

Currently, a large number of dairy products have appeared on store shelves.

In Novosibirsk, it is not often possible to find natural fresh milk for sale from private producers or peasant farms. Mostly Novosibirsk people use milk from the store in their diet. This project aims to find out the quality of milk from the store and show how you can investigate the quality of milk

object our research becomesmilk , which our parents, and not rarely, you and I buy at a regular grocery store.

Subject research is the process of determining quality milk.

Objective of the project:

Learn to identify a quality product (milk) at home.

Transfer of acquired knowledge, skills and abilities to the public by filming and showing a video about “experimental testing of milk quality at home”.

Show the advantages and disadvantages of a product of a certain sample, to determine the possibility of its use or unacceptability in nutrition.

Tasks project:

  • Conduct a theoretical analysis of the literature on this issue;
  • Conduct the necessary experiments to determine a quality product;
  • Draw conclusions and rationale for the work;
  • Make a video on the experimental testing of milk at home;
  • Showing a video at the school NPC (scientific and practical conference);
  • Placement of the video on the Internet and social networks.

Methods project:

Studying information on the topic;

Experiment;

Observation;

Comparison of facts;

Analysis of results;

Processing of results;

Formulation of conclusions;

Shooting video;

Processing and editing of video files;

Video broadcast.

Project product: determination of the quality of store-bought milk, a video about the methods of experimental study of the quality of milk.

Practical significance project lies in the fact that I conducted experiments to determine the quality of milk and shot a video for parents and students with recommendations for determining the quality of milk at home to determine the possibility of its use or unacceptability in nutrition.

THEORETICAL JUSTIFICATION OF THE PROJECT

Determining the quality of products by smell, taste and color cannot provide complete and reliable information, and sometimes it can be dangerous to health. You can check the quality of milk at home without resorting to the “testing” method. To do this, you do not need to conduct complex laboratory studies, it is enough that you always have at hand.In addition to diluting milk with water, starch, gypsum, chalk, soap, soda, potash, borax, lime, and even chemical products such as boric and salicylic acids are often mixed with it. Some of these substances are mixed in to make the skimmed milk look whole, not skimmed; others - to protect against rapid sourness, in general spoilage, to which milk is subjected to the sooner, the more foreign organic impurities it contains.
In fact, the admixture of these impurities is not able to protect milk from sourness. Moreover, even the most "innocent" of these impurities, for example, bicarbonate of soda, is in fact very harmful, and precisely because, as revealed by direct experiments, the admixture of, by the way, bicarbonate of soda serves as the best condition for the increased reproduction of various pathogenic microbes in milk. - cholera bacilli, tuberculosis and others. ("Encyclopedia of Technologies and Methods" Patlakh V. V. 1993-2007)

There are several methods for determining the quality of milk. Some of them require special laboratory conditions with the necessary equipment and reagents. But some can be done at home. Milk should be checked immediately after opening the package.

Compound

The first thing to check when buying milk is the composition of the product. Currently, in Russia there is a law according to which if powdered milk is added to milk, then the label must say that this is a milk drink and, accordingly, this must also be noted in the composition.

When buying a bag labeled "milk", we expect that we are paying for milk, and not for a milk drink that is made from dry mixes. However, sometimes we are deceived with impunity.

The situation with milk in our country, to put it mildly, is confusing. Despite the existence of GOST, technical regulations and other documents, a method has not yet been developed that would allow determining whether there is powdered milk in drinking milk.

Abroad, if the milk is reconstituted from dry, they write so on the packaging - “reconstituted milk,” explainsLarisa Abdullaeva, executive secretary of the Dairy Union of Russia.- We have come up with the term "milk drink", but no one indicates it on the packaging

(http://www.aif.ru/gazeta/number/379)

If on the milk you bought in the COMPOSITION section it is written that it is:whole milk means good quality milk.

If it is written: reconstituted or normalized, therefore, the milk is made from milk powder, or with its addition.

The amount of protein in milk decreases in winter and cannot exceed 3%. And the packages often indicate much larger numbers. There is no live milk with such indicators in Russia: animal selection has not been carried out for a long time, there are complaints about the quality of feed. If natural milk really contains high protein, the manufacturer will direct such valuable raw materials to cheese or cottage cheese, and will not make ultra-pasteurized milk from it. (from an interviewElena Petrova, OZPP expert).

If the packaging indicates a high protein content, then the milk has most likely been reconstituted.

Determination of impurities

It is quite easy to determine the "purity" of the product, for this you need to strain a certain amount of milk through a dense white cloth, or a cotton pad.

If you notice villi, any grains of a substance, it means that sanitary standards were not observed in the production of milk, and such milk can be dangerous.

"Dirty Glass"

During this check, we check the density of milk (fat content), therefore, after stirring the milk in a glass, carefully look at its walls, the “dirtier” your glass is, the better the quality of the milk. It should be noted that the layer of milk on the walls must be uniform.

Litmus.

Sometimes manufacturers, whose product stays on store shelves for a long time, add soda to milk, which slows down the souring process. You can determine the content of soda in milk using litmus papers.

Most likely, not every home has a paper acid-base indicator, but if you set out to check food at home before eating, it is not difficult to get one at a pharmacy.

With the help of litmus papers, you can check the acidic environment of products, in our case, milk.

Pour milk samples into different containers;

It is necessary to moisten one strip of indicator paper in the milk sample;

We wait 1-2 minutes and carefully examine the strip;

We draw conclusions on the color of litmus paper:

With complex adulteration of milk, one should be most careful about chemical impurities, for the detection of which this test can be of no small benefit. Unskimmed, whole milk has a very characteristic double reaction, which is that it is at the same time somewhat alkaline and slightly sour; as a result, a blue litmus paper soaked in whole milk turns slightly red, and a red one turns slightly blue.
On the contrary, if there is an excess of alkali in milk, for example, from the admixture of soda to it, then the red litmus paper turns very blue, while the blue one completely retains its color.
Similarly, if an acid, such as boric or salicylic acid, is mixed into milk, then blue litmus paper, moistened with such milk, turns bright red; red does not change its color at all.

IODINE

The presence of starch, which is added to milk to make it thicker, can be easily and quickly determined using ordinary iodine from a home medicine cabinet.

A few drops of an alcoholic solution of iodine should be dropped into a small amount of milk.

Staining in blue, will show the presence of starch in the product;

A yellow-orange color indicates the absence of starch in the milk.

Alcohol

With the help of alcohol, you can accurately determine whether milk is diluted with water. For this you need:

- to one part of milk, add two parts of alcohol;

- the resulting mixture is actively shaken for 1 minute;

- after shaking, it is necessary to pour the mixture of milk and alcohol into a plate or saucer, carefully observing the state of the mixture and fixing the time after which white flakes appear in it;

- rapid, within 5-6 seconds, the formation of casein flakes released from whey will indicate the high quality of milk;

- if the flakes appear late, then the milk is diluted with water.

By the time of formation of casein flakes, one can judge the degree of dilution of milk with water. If it took about a minute for the formation of flakes, then 20% of the volume was replaced by water, an interval of 25-30 minutes will indicate the content of 40% water in milk, and if casein flakes began to appear onlyafter 40 minutes, such milk is diluted with water by half.

7. Warm water.

By pouring a small amount of milk into a glass of warm water in a thin stream, it is possible to determine with a high degree of probability whether it has been diluted with water.

High-quality milk in the form of a white clot will gather in the upper part of the glass, glass, diluted milk will behave differently - it will almost completely dissolve in water, coloring it in an off-white color.

If milk is poured in quickly, good quality milk will first sink to the bottom of the glass, and then slowly dissolve when diluted with water immediately turns the water off-white.

8. Filter paper

Another way to determine the degree of dilution of milk with water . If you do not have filter paper at home, then you can use a paper napkin or toilet paper. The main requirement is that they must be of a sufficiently high quality.

Having dipped a thin stick, a toothpick or a match into the milk, you need to put a small drop of milk on the surface of the filter paper. It is very important that it be as small as possible and at the same time be as convex as possible, resembling a hemisphere. For the reliability of the result of such drops, it is better to put a few.

Since the filter paper has a finely porous surface structure, it will begin to absorb the water contained in the milk. Therefore, on the surface of the paper, a wet ring will appear around the drop, the width of the ring will be the greater, the greater the amount of water in the milk.

A drop of undiluted milk will create around itself a wet ring no more than 1 mm thick, which will dry at room temperature in about 2 hours.

The water spot around a drop of milk diluted with water by 10% will be noticeably wider and will dry faster - in about an hour. In half an hour, the ring around a drop of milk diluted by 30% will dry, and it will take only 10-15 minutes to dry the ring left by a drop of milk diluted in half.

Checking for antibiotics

The milk that we buy in the store undergoes a special treatment. It is purified from various impurities. In order to destroy microorganisms, pasteurization of milk, ultra-pasteurization and sterilization are carried out.

Pasteurization - heating milk from 63 degrees to a temperature close to the boiling point. Pasteurization destroys vegetative forms of microbes, and sterilization destroys spores at the same time. When boiling, the entire microflora of milk is destroyed, with the exception of spores that are resistant to the boiling temperature.

Sterilization milk aims to destroy all microorganisms. In this case, milk is first heated to 75 degrees, then heated under high pressure in a fraction of a second. In another method, the milk is sprayed and, at the time of spraying, heated to the temperature of superheated steam. Bacteria are instantly killed. The milk is then cooled and packaged.

Sterilized milk obtained in one way or another does not change its taste. In hermetically sealed containers, sterilized milk can be stored for a long time at room temperature.

UHT It is used to destroy microflora and at the same time preserve the natural properties of milk. Ultra-pasteurization is carried out at a temperature of 105 to 150 degrees with exposure from a few seconds to fractions of a second. Then the milk is quickly cooled in 4-6 seconds.

Unfortunately, at home it is impossible to check whether the purchased product is natural or made from milk powder. But checking milk for the presence of antibiotics and various substances that slow down the growth of bacteria is very simple. Natural and without additives, milk left at room temperature should turn sour in a day.Pasteurized milk turns sour for 2-3 days, ultra-pasteurized and sterilized milk may not turn sour for quite a long time.

PRACTICAL PART

The practical part includes a description of the work on the study of milk quality, in the framework of the above studies.

Milk test - we check the quality of milk at home

1. When buying, pay attention to the expiration date of milk and storage conditions. Buy only dairy products where there is refrigeration equipment. At the expense of the market - decide for yourself whether it is worth the risk. And pay attention, two hours is the maximum period for transporting fresh milk without using a refrigerator.

2. To test milk at home, purchase litmus paper. It will show the presence of chemical impurities in the milk. If the milk is not diluted, then the litmus test will remain unchanged. Litmus paper will determine if there is soda in milk (in an alkaline environment, litmus paper will turn blue). Baking soda is added to make milk last longer.

3. Also, in order for the product not to turn sour for as long as possible, salicylic acid can be dissolved in milk. If it is present in milk, then the litmus paper will turn bright red.

4. To increase the density of milk, dishonest producers can add starch. To check, you can drop iodine into milk. If the milk turned blue, then it could not have done without "innovations"!

5. To increase the volume, milk is diluted with water. Checking with alcohol (vodka). Pour a little milk into a glass, add alcohol (vodka) to the glass twice as much milk by volume. We mix everything. If the milk is of high quality, then flakes will appear, it is casein protein that has curtailed from alcohol. To better see the flakes, you can pour the mixture into a saucer of a plain dark color. In diluted milk, flakes do not form immediately, but after some time. The more water in the milk, the later the flakes will appear.

6. How can you detect chalk in milk. To do this, you can pour vinegar. If there is abundant foam, then there is chalk in the milk.

7. Long-term milk quality check. Defective milk will not pass this test!

Take a dry clean glass and pour milk into it. Cover it with a napkin and leave it on the table. Do not stir while observing.

Normal milk should taste sour in a day (maybe earlier, it all depends on the temperature in the room).
The next stage in the transformation of milk is curdled milk, the sour taste should be greatly weakened. Curdled milk should be a homogeneous mass, like jelly, which is easily mixed.

What can be seen during the observation and what conclusions can be drawn about the quality of milk:
- Milk turned sour in more than a day. This means that there are preservatives in milk.
- Initially, milk has a boiled flavor. This suggests that the milk was boiled, or there is a concentrate in its composition.
- It does not sour at all and after a while an extraneous smell appears in the milk. It indicates that this is not natural milk, it is a surrogate (maybe powdered).
- It turns sour in time, but yogurt is not formed in the form of a single jelly-like mass. So the milk was diluted with water.
- It turns sour in time and forms curdled milk of the desired consistency, but a thin sour cream film has not formed on the surface of curdled milk. This means that the milk is skimmed, i.e. partially driven through the separator, or diluted with reverse (not water), or the milk is simply not fat. This is not bad milk, some people just love it. The benefits of milk, especially those who follow their figure.

You can check the quality of milk at home. To do this, you do not need to conduct complex laboratory studies, it is enough that you always have at hand.

Litmus

It is likely that not every home has a paper indicator, but if you set out to check the quality of food, it is not difficult to purchase it at a pharmacy.

So, there are strips of litmus paper. What's next? And then moisten one strip of indicator paper in milk brought from a store or market, wait 1-2 minutes and carefully examine a strip of litmus.

Coloring litmus paper blue will indicate the presence of soda or other alkalis in milk, red litmus will react to an acidic environment resulting from the addition of acid-based bleaches to milk.

If the color of the litmus strip of paper has not changed, you can quietly rejoice - no one added soda, boric and salicylic acids to the milk you bought.

Iodine

The presence of starch, which is added to milk to give it thickness, can be easily and quickly determined using ordinary from.

In a small amount of milk, drop a few drops of an alcoholic solution of iodine. If the milk turns blue, then starch is mixed into it, and a yellowish-orange color indicates its absence in milk.

Alcohol

Using it, you can accurately determine whether milk is diluted with water, if 2 parts of alcohol are added to 1 part of milk, and then the resulting mixture is actively shaken for 1 minute.

After shaking, immediately pour the mixture of milk and alcohol into a plate or saucer, carefully observing the state of the mixture, fixing the time after which white flakes appear in it.

The rapid (within 5-6 seconds) formation of casein flakes released from the alcohol whey will indicate the high quality of milk, but if the flakes appear with a significant delay, you should know that the milk is diluted with water.

By the time of formation of casein flakes, one can judge the degree of dilution of milk with water. If it took about a minute to form flakes, 20% of the volume of milk was replaced by water, a time interval of 25-30 minutes would indicate a milk content of 40% water, and if casein flakes began to appear only after 40 minutes, such milk is diluted with water by half.

warm water

By pouring a small amount of milk into a glass with a warm thin stream, it is possible to determine with a high degree of probability whether it was previously diluted with water.

High-quality milk in the form of a white clot will gather at the top of the glass, diluted milk will behave differently - it will almost completely dissolve in water, coloring it in an off-white color.

Filter paper

Another way to determine the degree of dilution of milk with water. In the absence of filter paper, you can use a paper napkin or toilet paper, the main requirement is that they must be of a sufficiently high quality.

After dipping a thin stick, toothpick or match into the milk, place a small drop of milk on the surface of the filter paper. It is very important that it be as small as possible and at the same time be as convex as possible, resembling a hemisphere. For the reliability of the result of such drops, it is better to put a few.

Since the filter paper has a finely porous surface structure, it will begin to absorb the water contained in the milk. In this case, a wet ring will appear on the surface of the paper around the drop, the width of the ring will be the greater, the greater the water content in milk.

A drop of undiluted milk will create around itself a wet ring no more than 1 mm thick, which will dry at room temperature in about 2 hours. The water ring around a drop of milk diluted with water by 10% will be noticeably wider and will dry faster - in about an hour.

In half an hour, the ring around a drop of milk diluted by 30% will dry, and it will take only 10-15 minutes to dry the ring left by a drop of milk diluted in half with water.

Unfortunately, at home it is impossible to check whether the purchased product is natural or made from milk powder. But checking milk for the presence of antibiotics and various substances that slow down the growth of bacteria is very simple.

Natural and without additives, milk left at room temperature should be a day. If this did not happen, then the chemistry in it is unmeasured.

Let the milk you bought be always of high quality, whole and natural!


Milk is a product that we get used to from early childhood; neither children nor adults can do without it. Even if we do not drink milk, we use it as one of the components of ready-made meals, and also eat products made from it. It contains calcium, vitamins and other useful macro and microelements.

The dairy industry is one of the largest and developing areas of modern industry. Meanwhile, the quality of manufactured products is far from perfect. That is why the question: how to choose milk is very relevant. Another important question is how much milk adults can drink. According to the recommendation of the Ministry of Health, the consumption rate of dairy products for an adult is 325 grams per day. In case a person suffers from intolerance or partial lactose intolerance, which develops in some people in adulthood, even high-quality milk is not recommended.

On the shelves of shops you can find pasteurized and sterilized milk. Pasteurized is stored for 5-7 days. It can be considered more natural. The advantage of a sterilized product is a long shelf life, up to 6 months. However, it should be borne in mind that there are fewer useful substances in it.

Which milk is the best, and which disorders are most often found, you can find out by reading the results.

Are we always confident in the quality of the products we buy? In particular, when it comes to such a drink as milk. At present, the opinion about the benefits of milk for the human body is no longer so unambiguous, because the purchased version may contain a huge amount of impurities and additives harmful to the body, which simply level all those valuable qualities of a natural product for which we love it so much. But there are several proven ways to determine the freshness and quality of a dairy product that are available to us at home.

How to check the freshness of milk at home

Milk is a product unique in its composition, which is useful for a person at any age.

The freshness of cow's and goat's milk is checked in the same way, despite the fact that the composition of these products is slightly different. In goat, unlike cow, there are no caseins that cause allergic reactions. However, it is important for testing that both of these species contain proteins.

It is possible to determine the exact quantitative composition of proteins in milk only in laboratory conditions.

The soda method

  1. Pour half a glass of milk.
  2. Pour ½ tsp. soda.
  3. Let's look at the reaction. If foam appears, the milk is not fresh.

Boil method

  1. Pour some milk into a saucepan.
  2. We put it on the fire and wait for it to boil.
  3. If the liquid has curdled, the milk is spoiled.

Determining freshness by drop

Homemade milk has a high percentage of fat content, and thanks to this, you can check its freshness in the following way:

  1. We put a toothpick into a container with milk.
  2. We drip liquid on the nail.
  3. If the drop has not spread, the product is fresh. And if it spreads, then there is water in such milk, and it is not fresh.

The surest tool for determining if milk is sour is the nose. A sharp sourish smell is a clear sign of a product that is not fresh. You also need to look at the consistency and uniformity of the liquid. Uneven thickening or the appearance of white flake-like inclusions indicates that the milk has deteriorated.

Effective ways to check the naturalness and quality

To determine the quality and naturalness of milk, you need only one glass of drink

It is interesting. A very unreliable but fun way to test if milk is natural is to give it to a cat. The animal will turn away from the drink with additives. True, there is a great chance of error: firstly, a cat can be unpretentious, and secondly, manufacturers can be very resourceful in additives.

Antagonists of store-bought dairy products unanimously shout that all kefirs, curds and, of course, milk on the shelves are made from powder, that is, from milk powder. Perhaps the situation is not so clear, but if you decide to buy products in a supermarket or are just choosing a supplier of fresh milk, it would be useful to know about some ways to check the quality of a natural product. . The very first way to determine the naturalness of milk is to evaluate its color. If the product is yellowish, then this is the result of the work of the mammary glands of a cow or goat. But white or white with blue color indicates the presence of impurities. Resourceful manufacturers add lime, chalk, flour, starch to milk to improve the external performance of the product.

Detecting the presence of starch

The surest way to determine if there is starch in milk is to drop iodine into a healthy product.

In the manufacture of products, it is not uncommon to add starch to skimmed milk in order to give thickness in this way. Iodine is required to determine this additive in a drink.

Instruction:

  1. Pour some milk into a glass.
  2. We drip iodine.
  3. Let's look at the reaction. If the liquid has acquired a bluish tint, then there is starch in the milk. If yellowish circles have gone, then you are lucky - there are no additives in such milk.

Determine if there is water in milk

In addition to the method described above for determining the freshness and presence of water in a natural drink, there is another proven option - using alcohol. But this method is suitable only for cow's milk, since the casein contained in it is necessary for the reaction.

Instruction:


You can also check if there is any foreign liquid in the milk using warm water. This technique can be used for both cow and goat milk.

Instruction:

  1. Pour warm water into a glass.
  2. We begin to slowly pour in the milk.
  3. If the stream immediately mixes with water, then the product is diluted, and if it gathers in a clot at the top of the glass, then it is natural.

Antibiotics and other impurities

In order for milk to be stored longer, antibiotics are added to it. It is very easy to check their presence in the purchased product.

Instruction:

  1. We leave the drink in a container with a loosely closed lid for a day in a warm place.
  2. High-quality milk will begin to ferment and begin to resemble jelly. But the drink with additives will remain unchanged. This is because antibiotics slow down the growth of lactic acid bacteria contained in the natural product.

Manufacturers of dairy products are trying in every way to extend the shelf life of goat's and cow's milk. To do this, most often soda or salicylic acid is added to it. You can determine the presence of these impurities using litmus paper:


In principle, it is possible to detect the presence of any impurities using acetic acid:


Unscrupulous milk suppliers sometimes hide from consumers the fact that it is made from skimmed milk powder. In this case, you can test the drink for naturalness with nitric acid (it is sold in specialized chemical reagent stores).

Instruction:

  1. Pour milk into a glass.
  2. Add the acid drop by drop from the test tube.
  3. If the product starts to turn yellow and then turns orange, then it is not natural.

But sometimes there is no need to purchase a reagent; it is possible to determine the fact of milk recovery from powder by eye. When shaking in glassware, opaque particles remain on the walls.

How to check the fat content of a product

To check the fat content, any of the tests for the presence of water is suitable. After all, if the product is diluted, then its fat content is significantly reduced. But there is another test:

  1. We take two glasses, pour milk into one.
  2. We pour liquid from one to another.
  3. We evaluate the result - fatty milk will not leave streaks and marks on the walls of dishes, but diluted milk will be smeared in a glass. The same reaction will be with milk, to which palm oil has been added.

Excessive consumption of palm oil can cause problems with blood vessels. It is difficult to excrete by the body and contains almost no linoleic acid, which is valued in other oils.

Three criteria for assessing the quality of milk powder

We all know that milk can be natural and reconstituted, that is, obtained by diluting dry milk in water. We have dealt with the definition of the quality of the first type, now it's time to talk about how to assess the dry condition. To do this, you need to evaluate the powder according to 3 criteria.

Video: how to determine the naturalness of milk - "Home Laboratory"

The emergence of more and more new ways to make milk look like a natural product leads to the fact that consumers have to try different tricks to test a healthy drink. So, if you managed to find a supplier whose products passed all the tests with honor, then you are very lucky. Be vigilant and healthy!

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