Cow's milk is one of the most healthy foods for both adults and children. It contains a huge amount of components that our body needs. And such components as protein, sugar and fat are best absorbed in the human body. The higher the protein level in milk, the more it is valued. Therefore, increasing protein levels is a very important and time-consuming job. In developed countries, half the cost of this product depends directly on its protein content. To this end, producers of milk and dairy products ensure that cows are kept in good conditions and receive food rich in vitamins.
Acidity control is also very important, since in case of souring the product, it already becomes unsuitable for sale to consumers.
What determines the acidity of milk?
The chemical composition of milk depends on many factors. It is influenced by the conditions of the animal, its physiological state and more. The process of milk formation is quite complicated, in which the state of the animal’s external environment matters. On its formation and secretion on average 10% of all nutrients that enter the mammary gland with blood are spent. So, to get one liter of cow's milk, it is necessary that about five hundred liters of blood pass through the mammary gland. Its properties are constantly changing, from the moment of milking until it reaches the final consumer. Milk is significantly different in composition. Thus, colostrum contains twenty percent more protein than ordinary protein, which makes it much more useful. Such milk in its composition contains a large number of nutrients and minerals. Colostrum also contains a minimal amount of sour-milk microorganisms, which allows it to stay fresh as long as possible.
Degree of acidity
During storage of milk under the influence of sour-milk microorganisms that develop in it, lactose decomposes, as a result of which lactic acid is formed and acidity increases. Its level is expressed in degrees Turner (T).
Freshly milked milk has a degree of acidity of 16-18 T. But in addition to these indicators, buffering is an important characteristic. In milk, there are components due to which the pH does not change when acids and alkalis are added. The higher the buffer properties, the more reagents will be required to change the pH. Also, the increased acidity of milk is observed in those cows that graze in the summer in meadows or fields where cereals grow. This is due to the fact that in the composition of meadow grasses and cereals a reduced level of calcium. Scientists have long established a connection between the content of calcium in milk and sour-milk microorganisms. It was revealed that the less calcium in milk, the higher its acidity. Accordingly, with an increase in the calcium content in food, the acidity index decreases.
Acidity Meter
To determine the acidity of milk, farmers and other manufacturers use a specially designed device called a pH meter. This device initially measures the EMF (electromotive force) of the electronic system. After that, the temperature of the dairy product is additionally measured. In this case, the pH value, which is reduced to 20 degrees, is determined by a specially derived formula.
The pH meter for measuring acidity refers to the dairy and food industries. It can be used to measure the active acidity of milk and dairy products.
This method of determining the acidity of milk is today considered the most accurate.
PH meter action
In order to determine the level of acid microorganisms in milk, the sensors of the device, which contains a temperature measuring electrode and a silver-silver comparison electrode, are immersed in it or any other dairy product. Now, using the pH conversion, the EMF that develops in the product and its temperature are determined.
Further calculations are made according to the formulas.
What is titratable acidity?
The acidity of the product is classified as active and titratable.
To determine the second, it is necessary to use the alkali titration mechanism. In general, this is a complex chemical process, as a result of which titratable acidity in milk will be determined. Its degree is above 16-18 T. The titratable acidity of colostrum is 5-6 T higher than that of ordinary milk. This is due to the fact that the level of whey proteins is significantly increased in it. And if we consider milk from sick animals or old milk, then their acidity, on the contrary, will be 5-8 T lower than in milk from a healthy animal. Such indicators are associated with the presence of salts - chlorides. The titratable acidity, as well as the active one, is greatly influenced by the conditions in which the animal is kept, its genetics, nutrition, breed and state of health. For example, if there is a lack of salts in the feed, the titratable acidity of the milk will be 23-24 T. With these indicators, the product is subject to rapid souring.
In terms of titratable acidity, technological processes are controlled not only for milk, but also for all dairy products that pass through lactic acid fermentation.
Quality standard
Russia has established the requirements that milk must meet. GOST 31450-2013 is a quality standard that applies to drinking milk packaged in consumer packaging after heat treatment. In accordance with the requirements, the product should not contain flakes, stray lumps of fat. According to GOST, milk should have a uniform white color with a bluish color for a low-fat product, with a light cream color for pasteurized and a creamy shade for melted one. An important indicator of quality is the absence of extraneous odors and taste.
Due to its useful qualities, milk can replace a large number of products, but not one other product can not replace milk. In addition to fats, proteins and carbohydrates, which are in it in a balanced ratio, calcium is present in milk, which is easily absorbed by the body.