Almost all parents give their children cow's milk, since, as is known, this product contains a huge amount of nutrients and vitamins necessary for the proper development of the baby's health. Store-bought dairy products are sterilized, so during processing most of the beneficial qualities are destroyed. For good functioning of the kidneys, heart and liver, you need to drink half a liter of milk every day. Where do human muscles get strength and energy? Nutrition comes through protein, which is part of the valuable liquid. It produces immunoglobulins that fight various viruses.
You should not exclude milk from your diet also because it reduces the acidity of gastric juice, this improves the functioning of the digestive system during gastritis, ulcers and other inflammatory processes. For breakfast, milk porridge is indispensable for the body. If you monitor the conditions of detention, a cow can produce about 20 liters of milk per day.
Cow's milk
Why does milk smell like cow?
In short, most often the problem lies in non-compliance with simple rules of milking technology, sometimes in the health of the animal itself. This fact requires serious consideration, since sellers of homemade milk assure buyers that they are accustomed to city life, to packaged containers containing a liquid product, and natural milk should have “echoes” of a cow in taste and smell. But that's not true!
Milk smells like cow
Everyone knows from school how a cow gives milk. But there are some nuances here too. Before each milking, the cow's udder must be washed with warm water, and the cow must be cleaned regularly. Otherwise, bacteria will get into the valuable product and it will not be stored for long. There are usually no problems when eating fresh food. Silage and haylage have a specific aroma, so it cannot be eliminated. A dry and warm barn will not only provide cattle with comfort, but will also contribute to the quality of the taste. Dirt and waste in the room should be removed.
The benefits and harms of fresh milk
The temperature of fresh cow's milk reaches 30°C, and the calorie content is 70 kcal. The main value is in the uncooled milk, from which steam emanates; if it stands uncovered for some time, its usefulness is sharply reduced (several hours may be enough). It contains saturated and unsaturated fats in sufficient quantities, their amount in the product is 4 g. Since milk is a low-calorie product, overweight people can easily include it in their diet. In addition, it improves vision and reduces the likelihood of developing rickets and osteoporosis. Beneficial properties include strengthening the immune system, as well as regulating the functioning of the nervous system.
Important! Veterinarians say that the product contains up to 96% of various bacteria. Milk may contain tuberculosis, intestinal and pseudomonas bacilli, helminths, and salmonella.
Individual intolerance to this product can provoke attacks. To reduce the risks of unwanted health effects, livestock farmers recommend boiling fresh milk before drinking and waiting until it cools.
What is whole cow's milk?
The product can be subjected to various treatments, which essentially change its composition. Whole cow's milk does not undergo any processing, which is why it is called raw. The only thing to clean it is to filter it, since during milking small debris can get into the liquid: straws, hairs from the skin of a cow. Then it can be diluted and passed through a separator to separate the cream.
Note! It is better not to give whole milk to children, as it can cause stomach upset due to the large amount of fat in it (more than 2.5%).
The beneficial qualities of this milk include the fact that it helps normalize sleep. To “prepare” the body for rest, experts recommend drinking 1 glass of warm milk with 1 teaspoon of honey 1 hour before bedtime.
This product is also a diuretic, so it removes harmful substances from the body. With regular consumption of whole cow's milk, metabolism is restored. Beneficial properties have also been noted in cosmetology, since milk with natural ingredients in its composition helps to moisturize and reduce inflammatory processes on human skin.
Whole cow's milk
People with lactose intolerance should be wary of this type of product. According to statistics, about 15% of the world's population suffers from this problem. Due to the fact that milk is considered a strong allergen, you need to monitor the body's reaction to its consumption. And if there is one, then you need to remove it from the diet. However, people with allergies not only can, but should also include in their food fermented milk products obtained during the processing of whole milk, but within reasonable limits.
Important! The consumption of unprocessed milk should be normalized for women during pregnancy. Half a liter a day is the maximum.
How much cholesterol is in cow's milk
When answering this question, the level of cholesterol in milk is determined in relation to the proportion of fat content. So, for example, a less fatty product (1%) contains 3.2 mg of this substance, a 2% product contains 10 mg, 3% fat equals 15 mg, and 6% contains 23 mg of cholesterol. If a person has a high level of lipids in the blood, then milk from the cow should be consumed in small doses or completely excluded from the diet. If there is no liquid product with a lower fat content, then you can simply dilute it with water.
Important! For the sake of health, doctors advise older people to take 1.5 glasses of milk a day, and it is advisable to do this with morning and evening meals.
Why does a cow's milk turn sour quickly?
The most common explanation lies in the storage temperature of cow's milk. The optimal conditions for the growth of bacteria in a fermented milk environment is a temperature of 25-30°C. However, even under normal conditions when the product is present, milk sometimes begins to sour and acquires an unpleasant color and odor. There are several explanations for this. If a product placed in the refrigerator produces sediment, this may indicate the presence of pathogens that release toxic substances. This can happen due to inflammatory processes in the udder. During milking, bacteria enter the milk, which leads to early fermentation of the product. In such a situation, you need to resort to treating the cow using antibiotics. And during this period, it is better to refuse to accept milk from this animal.
A disease of the cow, such as a follicular cyst, contributes to the rapid curdling of milk, which becomes significantly less. If this is observed, you need to immediately begin treating the cow.
Milk turns sour quickly
In the first months of milking, a cow may be diagnosed with ketosis. This also explains why a cow’s milk quickly turns sour. The disease appears as a result of poor-quality feeding, due to which acetic acid and acetone accumulate in large quantities in the body, which leads to improper metabolism. As a result, the product spoils quickly, although it is fresh.
To determine the true essence of the problem, it is worth paying attention to how correctly the milking took place (if milk remains in the udder, this negatively affects the health of the animal), the age of the cow, her diet, the weather in the pasture, hygiene in the barn and sanitary standards during milking time.
Why doesn't milk from a domestic cow turn sour?
The main point is the correct feeding of cattle, or rather, overfeeding them with protein foods. If you do not maintain the correct proportions of sugar and protein in food, then the cow's milk will turn sour for a very long time. This problem can also occur when feeding an animal cabbage, pulp, or plants that taste sour. As a result of improper nutrition, metabolism is disrupted, which makes it difficult for milk to sour. There is an accumulation of ketone cells, and this is dangerous because it can cause poisoning due to the rotting of proteins and the destruction of fats, processes that occur before the souring stage. The taste becomes rancid. To solve the problem, you can resort to reducing cake in the diet, and instead of alfalfa hay, it is better to use meadow hay. You can also add a little baking soda to the food, as this substance helps to ferment the milk.
Milk from a domestic cow does not turn sour
The container that contains the milk is also important. For this purpose, it is best to use glass or ceramic containers. Galvanized and copper containers are strictly prohibited. It is better to use a tightly closed lid to prevent air from getting inside. Proper washing of the jar can also eliminate the problem. For example, it is better to rinse immediately with warm water. If it is cold at first and then warm, the milk will take longer to sour.
Why drink homemade cow's milk every day? It is considered an indispensable food product not only for small children, but also for adults, since it has a full range of nutritional micro- and macroelements. Vitamins in cow's milk help strengthen the immune system, improve the functioning of the gastrointestinal tract, and calm the nervous system. To choose the best product, livestock breeders recommend paying attention to the health of the cattle, as well as how clean, warm and dry the premises are, and whether sanitary standards are observed during milking. If all this is provided for the cow, she will give the most delicious milk!
Igor Nikolaev
Reading time: 3 minutes
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People may be allergic to regular milk. And in sour milk, protein and lactose are modified. The digestive system is more prepared for such a product. Many people prefer lactic acid drinks because of their taste and beneficial qualities. But sometimes the nutrient liquid turns sour at the wrong time and becomes unusable. Why does a cow's milk sometimes turn sour too quickly?
Milk from a cow can stay fresh at room temperature for less than a day. When placed in the refrigerator, it can last for three days, sometimes up to a week. Leukocytes, immunoglobulins and other substances prevent milk from turning sour. They have bactericidal qualities that prevent harmful bacteria from growing.
After this period, the milk begins to sour. The fact is that it contains lactic acid bacteria.
There are not very many of them in the milk itself, but they enter the can from the udder, from the environment, and begin to act. The product creates a wonderful environment for them. The higher the temperature, the more actively they reproduce with the help of protein, fats and lactose.
List of reasons for sour milk
Once the milk is boiled, it curdles and separates into lumps and whey in the pan. But if the process occurs before the required shelf life, the product acquires a sour taste and smell, there are explanations for this.
Diseases
Changes in the composition, consistency or reactions of milk often occur due to inflammation or infection. Some of them occur in an acute form, some more covertly:
- mastitis affects the souring process of the product. Inflammation of the udder causes an increase in the number of harmful bacteria. They get into the milk and cause fermentation. It has to be treated with antibiotics. You should not drink milk at this time;
- a follicular ovarian cyst causes the product to quickly curdle when heated and sour, acquiring a bitter taste. When a cow is sick, milk is given in smaller volumes. The cyst must be treated with the help of a specialist;
- Among the causes are ketosis. This is a metabolic pathology due to improper feeding. During this period, excess acetone and acetic acid are found in milk. To help the animal recover, the diet is changed and vitamins are introduced.
Storage and milking methods
One of the simple factors influencing the rapid souring of milk is the storage temperature.
Lactic acid bacteria enjoy life in warmth - from 25 to 30 degrees. Once the temperature drops to plus fifteen degrees, fermentation will slow down.
Thus, in the refrigerator this process and oxidation of the product proceeds more slowly than at room temperature.
Another reason why a cow’s milk quickly turns sour is basic unsanitary conditions:
- washing hands and clean clothes should be the first rules when milking;
- The milk container is provided not only clean, but also dry;
- the udder is cleaned with warm water and wiped dry with soft tissues;
- The paddock must be cleaned of dirt and manure and bedding regularly changed.
If these rules are not followed, then foreign objects and dust may get into the milk, along with a huge amount of bacteria. They cause it to sour quickly. After completing the process, the liquid must be poured into clean containers, filtered through cheesecloth. It is recommended to boil the latter or simply change it every three days.
Cow diet
The cow's food affects the quality of milk. The healthier, fresher and more complete the diet, the richer and richer the composition of the product will be.
For example, in the second half of summer some herbs begin to bloom. Why does a cow have a lot of milk in this season, but sometimes it quickly disappears? Many of the plants affect the taste of milk and help reduce its shelf life. These include fresh beet tops. Before giving it to the cow, the tops are dried for several days. Then the oxalic acid evaporates.
It is advisable to monitor what the cow eats in the pasture. In addition to the fact that heavy foods, pieces of vegetables and other food cause digestive problems, some contribute to the souring of milk.
Prevent souring
The only sure way to protect milk from rapid souring is boiling. Sterilization of the product allows it to be stored for seven days.
People have long noticed that milk becomes sour during a thunderstorm, but scientists do not yet know why milk sours faster in bad weather. It is believed that electromagnetic waves influence the fermentation process, but this has not been proven.
The process of fermentation or curdling of milk is familiar to everyone since childhood. But many people mistakenly believe that milk turns sour due to high temperature. This is not true, or rather not entirely true. The fermentation process is accelerated by high temperatures, but even in the refrigerator, milk will sooner or later turn sour.
Causes of sour milk
It's all about streptococci, of which there are a lot in milk. They react with milk sugar, which provokes the release of lactic acid. Since the shape of such bacteria resembles a rod, they are called “milk” or “Bulgarian” rod. Bulgarian - because they were first studied by Ivan Mechnikov, who studied Bulgarian fermented milk products and their effect on the body.
He wasn't the only one who wondered why the milk turned sour. French chemist Louis Pasteur proved in his research back in 1857 that fermentation is caused by bacteria that are present in the product. His early research was related to wine (this is not surprising, since France is a world wine producer). Pasteur proved that the main reason why wine turns into vinegar is yeast microorganisms. A good way to prolong the freshness of food is to heat it to a temperature of 50-60 degrees and hold it for some time. Today this method is used mainly for juices, milk and beer, and we call it "pasteurization".
In the refrigerator it remains fresh for up to 2-3 days, at room temperature it spoils much faster. Unprocessed cow's milk, which is kept at temperatures up to 20 degrees Celsius, becomes sour in about 10-20 hours.
But why does milk sour? How does this process happen? And can you drink it stale? Let's answer these and other questions.
How and why does the process of souring occur?
Milk contains a special milk sugar called lactose. There is not much of it, only 4.7%. Lactose is an excellent nutrient medium for bacteria and various microorganisms.
This drink also contains proteins:
- albumen,
- casein,
- globulin.
In addition to lactose and proteins, milk also contains lactic acid bacteria, which enter it from the cow's udder, from her milk ducts and the environment. There are very few of them in a fresh product, then they begin to multiply and their number increases.
During their life, these bacteria feed on lactose and produce acid, that is, they convert milk sugar into lactic acid. As a result, the acidity of the drink increases, and proteins, in particular casein, coagulate.
It is with the help of lactic acid bacteria that many fermented milk products are made:
- cottage cheese,
- curdled milk,
- sour cream,
- Ryazhenka and others.
During production, they are specially added to fresh milk to create the desired product.
There are different types of lactic acid bacteria: they belong to the family Lactobacillaceae, which in turn is divided into Lactobacilleae and Streptococceae. Most often, the first type of bacteria is used to ferment milk - lactobacilli, since they act much faster.
Why does milk sour more slowly in the refrigerator, but faster in the room?
Why does milk that was stored at room temperature sour faster, but when storing a drink in the refrigerator, it may not spoil for up to several days?
Low temperature slows down fermentation
The explanation is simple: the optimal temperature for the life of lactic acid bacteria is from +25 to 30 °C. If it drops to +15, then fermentation slows down. Therefore, when storing milk in the refrigerator, the process of bacterial growth, and hence the souring process, is suspended.
Excess bacteria due to unsanitary conditions
Why else might the process of milk souring accelerate? If the milkmaid did not maintain cleanliness or worked in unsanitary conditions, then a large number of bacteria could get into it. Sometimes the dirty container in which the drink was stored is to blame.
If there are a lot of bacteria, the milk sours much faster than usual, even when stored in the refrigerator.
Why does a store-bought drink last so much longer than a natural one?
Because store-bought milk is pasteurized before sale. It is heated to a temperature of 60 to 80 °C, which kills the bacteria. Therefore, such a product is stored much longer.
It turns out that such milk should not sour at all. But this does not happen, since when heated, spores of microorganisms survive, which begin to develop as soon as conditions become favorable. This processing of dairy products extends their shelf life, but does not destroy beneficial substances.
Why does milk sour in a thunderstorm? And is this true?
There is a belief that milk turns sour during a thunderstorm much faster than usual, and it doesn’t matter whether it was in the refrigerator or just standing in the kitchen. I would like to say that this is a myth, another superstition that it’s time to forget about. But the facts say otherwise.
Indeed, milk sours much faster during a thunderstorm than on other days. It has not yet been possible to reliably identify the reason for the acceleration of the activity of lactic acid bacteria, but there are several hypotheses that explain this phenomenon.
Special electromagnetic pulses
Scientists believe that long-wave electromagnetic pulses, which were called spherixes, are to blame for accelerating the process of milk ripening. They can be detected even at a distance of several hundred kilometers from lightning discharges. However, it is not yet entirely clear how exactly these impulses affect the drink.
It is interesting that during the days when spherixes are active, not only milk curdles, but other compounds also undergo changes: for example, people’s blood thickens, and in printing plants the permeability of gelatin changes.
Favorable conditions for bacterial growth
There is another explanation for this phenomenon. Scientists believe that lactobacilli begin to process milk sugar into acid faster during a thunderstorm due to more favorable conditions. Everyone knows that when it rains, the humidity and temperature of the environment increases.
Is it possible to drink a sour drink?
We figured out why and how milk sours. But is it worth drinking it, and is it harmful? You should not refuse a sour product, since it is no less useful than fresh, but it is absorbed many times better (sour milk - 90%, fresh - 32%).
Sour milk is very healthy (no less than fermented milk products): thanks to its regular intake, the immune system is strengthened, the intestinal microflora and the functioning of the digestive tract are improved. Therefore, it is recommended to drink it for those who suffer from constipation. In addition, it contains vitamins B, E, A, D and a lot of calcium.
And even if you don’t like sour milk, you shouldn’t throw it away - you can make excellent dough from it, for example, for pancakes, donuts or pancakes.
Video: what can you quickly and deliciously cook from sour milk?
Milk is a very valuable food product. It’s not for nothing that our ancestors called the domestic cow “nurse.” Thanks to its unique properties, it is a source of many useful substances and the basis for the production of a large group of dairy and fermented milk products. Such production is possible due to the drink’s tendency to ripen. To understand why milk sours, let's figure out what it consists of.
What substances are contained in milk
Milk is intended to feed young mammals. It contains the full range of nutrients necessary for the growth and development of newborns. The digestibility of nutrients is very high and approaches 95%.
Moreover, the milk of animals of different species differs significantly in calorie content and quantitative content of biological substances. Let's take a closer look at the composition of cow's milk. It contains the following substances:
- Water – 87.5%.
- Fats – 3.5%.
- Proteins – casein, albumin, globulin – 3.3%.
- Milk sugar – lactose – 4.7%.
- Macro- and microelements (mineral part) – 1%.
- Vitamins.
- Enzymes.
- Antibodies that protect newborns from infectious diseases.
Milk also contains a certain amount of bacteria, which are classified as normal microflora. They are the answer to the question “why does milk sour?” The biology of microbes and, as a result, the type of fermentation they cause varies.
Bacteria causing desired fermentation
Lactic acid and propionic acid bacteria, kefir grains and milk yeast participate in the “useful” fermentation of milk.
Lactic acid microbes are naturally found in milk and are the main “culprits” why milk turns sour. The biology of bacteria is based on their processing of lactose into lactic acid. As a result, the acidity of the drink increases, and the casein protein coagulates. Some types of lactic acid bacteria are added to milk specifically to produce yogurt, cottage cheese, fermented milk cheeses, sour cream and acidophilus. This group includes: acidophilus, Bulgarian and cheese lactic acid sticks; lactic acid streptococci.
Propionic acid bacteria are introduced into milk during cheese production. As a result of the processing of milk sugar, propionic and acetic acids are formed and carbon dioxide is released. Along with lactic acid fermentation, alcoholic fermentation can also occur in milk. It is caused by specific yeasts and is used in the production of kefir.
To obtain curdled milk, it is enough to leave whole milk in a warm place for 1-2 days. But for the manufacture of other products, the necessary microorganisms are added to the prepared substrate. This explains why milk sours with one or another result.
Tasteless curdled milk
In addition to the desired fermentation, some microorganisms cause butyric acid fermentation. That's why sour milk is bitter. Spore-forming butyric acid bacteria convert milk sugar into carbon dioxide, butyric acid and hydrogen. As a result, milk acquires a bitter taste and unpleasant odor. This fermentation occurs mainly in sterilized and pasteurized milk, as well as in cheeses. The fact is that butyric acid microbes tolerate boiling temperatures for a long time (up to 30 minutes) and remain the only inhabitants capable of fermenting the product.
Another reason why milk turns sour and acquires an unpleasant taste may be putrefactive bacteria that develop in fresh milk if it is contaminated or if storage conditions are violated. Putrefactive bacteria exert their effect on the product at temperatures below +10°C, lactic acid bacteria are viable at + 10°C - +20°C. Unlike lactic acid microbes, putrefactive microbes are not killed during pasteurization, so milk from a package often “goes rotten” rather than fermented. In this case, microorganisms break down the proteins and fats of the milk, which leads to the appearance of decay products with a characteristic rancid or rotten odor.
Why does milk turn sour quickly?
The speed of milk fermentation depends on several factors.
- The optimal temperature for the development of lactic acid bacteria is from +30°C to +40°C. At this temperature, milk sours very quickly. So store the product in the refrigerator at +4°C.
- Milk bought in a store quickly sours even when stored in the refrigerator due to violations of production technology. This could be: non-compliance with the sanitary regime on the farm during milking and transportation, failure in the process of sterilization of the product, violation of the integrity of the packaging, poor-quality packaging, and so on.
It should be noted that for fresh milk, ripening is a natural process; at room temperature, it begins approximately 12-24 hours after milking from one cow. Mixed milk sours faster. To extend the shelf life, technological methods such as pasteurization and sterilization are used. They are based on temperature treatment of the product, but differ in the mode of exposure.
Pasteurization
Pasteurization of milk is carried out in several ways:
- Maintain for 30 minutes at +65°C.
- At a temperature of +75°C for 15 to 40 seconds.
- Temperature +85°C, processing time 8-10 seconds.
Such milk retains a significant part of the vitamins and enzymes, and most bacteria die. Only heat-resistant microbes remain “in service.” This explains why milk does not sour for a long time. Pasteurized milk can be stored in the refrigerator for 2 weeks. This product is also used to introduce various microorganisms and create targeted fermentation.
The most optimal way to preserve maximum nutrients is ultra-pasteurization. With this technology, milk is exposed to high temperature (+135°C) for 3-4 seconds. Then the product is cooled to +4°C and packaged in sterile packaging. Unlike conventional pasteurization, persistent spore forms (including putrefactive bacteria) die. UHT milk can be stored in the refrigerator for up to two months.
Sterilization
Sterilization kills all microorganisms. This milk is sterile, packaged in aseptic containers, and has a shelf life of up to 12 months. Everyone knows why homemade milk does not sour after boiling - because the bacteria die. But at home it is not possible to carry out high-temperature treatment and provide a bacteria-free work area and aseptic packaging.
But in industrial conditions, milk is sterilized at a temperature of +120 - +150°C for 20-30 minutes. Such a product is of less value because most of the vitamins and enzymes are destroyed. Also, lactic acid derivatives cannot be prepared from it.
Doesn't milk from a domestic cow turn sour?
Another reason why cow's milk does not sour may be metabolic disorders in the cow's body. If the ratio of sugar and protein in food is incorrect, protein overfeeding causes a disease called “ketosis.” Ketone milk is very harmful to the human body; it is practically not fermented, and the separated cream produces sour cream with a bitter aftertaste.
Milk fermentation products
- Fermented milk products have been known since ancient times. Each culture has its own ways of preparing this wonderful and healthy food. They differ mainly in the initial composition of the milk and the starter added.
- Curdled milk is easy to prepare at home. To do this, add starter to warm boiled milk - a spoonful of yogurt or sour cream. Keep in a warm place for about a day. Ryazhenka is Ukrainian curdled milk made from baked milk.
- Acidophilus is recommended for people with intestinal diseases. The product perfectly restores the microflora of the gastrointestinal tract.
- Fruit and berry fillings are often added to yogurt.
- Kefir comes in different varieties. Kefir grains added to the original product cause lactic acid and alcohol fermentation. The alcohol content in the drink ranges from 0.2% to 0.6%, depending on the duration of maturation. You can make kefir at home, but to do this you will need to get a culture of the fungus. In ancient times, kefir was so valued that the leaven was vigilantly guarded from prying eyes and passed from mother to daughter as a dowry.
- Kumis is prepared by the peoples of Central Asia from mare or camel milk. It has healing properties for diseases of the stomach and intestines, tuberculosis.
- Cheeses, cottage cheese, and cultured butter are also produced using a variety of starter cultures.
Store milk and lactic acid products in clean, sealed containers, observing the temperature conditions and terms specified on the packaging by the manufacturer. Follow the recommendations and the question “why does milk sour quickly?” will not arise. If there are no clear instructions on the storage mode, focus on a temperature of +4°C - it is suitable for almost all dairy products. Remember that dairy foods require careful handling, and spoiled products can cause serious poisoning.
