Milk, as you know, is a perishable product. It must be stored and transported correctly. Otherwise, the consumer will not get too tasty, and perhaps even a product unsafe for health.
Preprocessing steps
Milk spoils primarily due to the fact that it is an ideal environment for the development of microorganisms. Therefore, immediately after milking, it should be exposed to:
At milk processing enterprises, the following are also carried out:
In some cases, the primary processing of milk on farms or factories may include procedures such as pasteurization and sterilization. This product is transported from farms to processing sites in tanks or jars, which, of course, must be kept clean.
With technological acceptance, the primary processing of milk can be quite complicated. In its implementation, farms use a variety of different, often expensive, equipment. In any case, on each farm for the primary processing of the manufactured product, special premises are mandatory.
In large farms, such a procedure can even be performed in separately built buildings specially built for this purpose. In such buildings, among other things, even whole lines for the primary processing of milk are often installed.
Cleaning methods
In milk, even with the most careful observance of sanitary and hygienic norms of milking, there are always, among other things, various kinds of mechanical impurities and suspensions. On farms, depending on the type of equipment used, two methods of milk purification can be used. Both of them allow you to remove mechanical impurities quite effectively.
If a hand-held portable apparatus is used for milking in the household, cleaning is usually done by pouring milk into jars. A mesh metal grill is pre-installed on the neck of such containers. Further, gauze folded several times is laid on it. Then the actual pouring of milk into the flask is made.
Sometimes, instead of gauze, special factory filters can be used to clean a milking product on farms. Such devices are also simply stacked on the neck of containers before pouring milk into them. One such filter is usually designed to fill 2-3 jars. Further, such devices are thoroughly washed in a warm solution of detergent. Depending on the type of material used for the manufacture, after 10-180 days the filter must be disposed of.
When using automated milking lines, product cleaning on farms is usually done using a different technology. In this case, a filter cloth cover is simply put on the expanded end of the milk line.
The most effective cleaning method
On large farms, milk can also be passed through a special centrifugal separator to remove solids. The product itself is first poured into such an apparatus. Next, the separator is included in the network. Thanks to the rotation of the drum of this device, even the smallest particles, as well as bacteria in the processed product, are nailed to the walls. It is believed that the mechanization of the primary processing of milk at this stage and the use of such a technique allows removing up to 99.9% of microorganisms from milk.
Sanitary requirements
It is believed that impurities are best removed from milk when processed almost immediately after milking. That is, when the temperature of this product during filtration or centrifugal cleaning is 30-35 degrees. But in any case, according to sanitary rules, milk should be processed in order to remove mechanical impurities no later than 2 hours after milking at a temperature of at least 25 ° C.
What is cooling for?
The acidity of milk under normal conditions can increase very quickly. And in order for this product to retain its properties until it is sold or processed, cooling is necessary. For example, at a temperature of 12 ° C, milk does not begin to sour for 10 hours. That is, the total number of microorganisms in this period does not increase in it. At a temperature of 2-4 ° C, the development of lactic acid bacteria stops altogether.
Cooling Standards
This procedure, which is the most important stage of the primary processing of milk, is considered one of the most energy-intensive on farms. For cooling 1 ton of milk, the cost of electricity can reach 40-50 kW / h. After cleaning, according to the regulations, such a product should be cooled in the summer to +2 ... + 4 ° C, in winter - to +6 ° C. This avoids spoilage for a long time. In any case, the milk on the farm should be cooled to +4 ... + 7 ° C a maximum of 4 hours after milking.
Primary Milk Processing Technology: Cooling
This procedure can be performed on farms using several methods:
In running or ice water in jars.
In cooler tanks.
In special plate or irrigation installations.
It is believed that the most rational cooling technology in the primary processing of milk on farms is a two-stage. This technique can significantly reduce energy costs on farms. Using this technology, milk is cooled:
Sometimes, direct cooling tanks are also used in farms in the premises for primary processing, into which you can collect the product from several milking parlors and send it for sale within 2 days. In addition, such equipment is used to heat water through heat exchange. That is, the mechanization of the primary processing of milk at this stage allows you to save both on electricity and transportation.
What sanitary rules must be observed during transportation
Purified and chilled milk from farms can be transported in tanks or jars. At the same time, when transporting this perishable product, of course, certain requirements should be observed:
The machine used to transport milk must have a passport issued by the territorial body of the Sanitary Inspection. It is supposed to confirm such a document every 6 months. Passing transport without a passport to the territory of the dairy is prohibited.
It is also impossible to transport milk along with meat, fish, poultry, eggs and some other products. In addition, it is forbidden to transport this product in those vehicles that previously transported pesticides, gasoline, kerosene and any strongly smelling substances.
The forwarding driver must have a personal medical book with notes on passing examinations. Carrying milk is allowed only in protective clothing.
Milk from cows with mastitis, leukemia, brucellosis, etc., should be transported in a separate container.
In summer, the temperature of milk should increase during transportation no more than 1-2 g per 100 km.
According to the regulations, in summer, the total term of loading / unloading and transportation of milk that has undergone the primary processing of milk in jars in special refrigerated refrigerators should not exceed 6 hours, and in conventional on-board machines - 2 hours.
Tank carriage
This method of transporting milk to enterprises is very often used by large farms. Tanks are filled in households under a vacuum created by a pump or a car engine. Each section of such a container must be hermetically sealed. The product is delivered to the tanks via milk pipelines to the tank from below. This avoids the appearance of foam.
Milk is drained at the factory by gravity or under the influence of a special pump. Inspection of tanks and their washing are carried out through special hatches.
Enterprise Acceptance
Milk from the farm is delivered to the factory to the reception workshop, in which such equipment must be provided:
A preliminary check of milk brought from the farm must be carried out by a receiver with the appropriate qualifications or a foreman with the obligatory participation of a laboratory assistant. Upon arrival of the tanks, these specialists first of all examine the container for its cleanliness. Contaminated jars must be well rinsed before draining milk.
After opening the containers, the persons responsible for acceptance perform, among other things, the following procedures:
In the future, milk is subjected to the most thorough laboratory tests for the presence of pathogenic bacteria, various kinds of harmful impurities, etc. For sale, this product, of course, must be supplied with nothing infected and absolutely pure. Unfortunately, very serious, dangerous diseases can be transmitted through milk to humans.
Sterilization
This procedure is used on farms, and sometimes in processing plants, to kill both spore and vegetative bacteria. For sterilization, the milk during initial processing at the farm or plant warms above boiling point. Several methods can be used for such processing:
at a temperature of +103 ... + 108 ° C in autoclaves and bottles for 14-18 minutes;
at a temperature of +117 ... + 120 ° C in continuous sterilizing bottles for 15-20 minutes;
at a temperature of +140 ... + 142 ° instantly, followed by pouring into sealed paper bags.
The milk sterilization procedure allows you to store it in a sealed container even at room temperature for a very long time. But at the same time, the quality of the product after performing this operation, unfortunately, is deteriorating. So, for example, during sterilization in milk, up to 50% of vitamins C and B 12 are destroyed. In addition, rennet coagulability of this product worsens.
Pasteurization
This procedure often also becomes one of the stages of primary processing of milk on farms. During its implementation, the product can be heated to a temperature of +63 ... + 90 ° C. The main goal of pasteurization, as well as sterilization, is the destruction of pathogenic microflora. The milk subjected to this procedure is stored in the subsequent much longer. It is believed that by pasteurization it is possible to destroy up to 99.9% of pathogenic bacteria. That is, the product eventually becomes almost sterile.
Like sterilization, this procedure can be performed directly on farms and factories. It is pasteurization that is the main way to neutralize the pathogenic microflora in milk that goes to shops, canteens, etc.
The main modes of such processing in farms and factories can be applied in three:
at a temperature of 63-65 ° C for 30 minutes;
at a temperature of 72-76 ° C for 15-20 minutes;
instantly at a temperature of 85-87 ° C.
Equipment for the primary processing of milk at this stage can be used, for example, this:
When using all three modes, the properties of milk can vary slightly. So, after the most “gentle” pasteurization in the product, albumin begins to denature. At temperatures above 85 ° C, calcium is cleaved from casein in the product. Under the same conditions, milk, among other things, acquires a specific aroma and taste that are familiar to many consumers.
As with sterilization, during pasteurization, vitamins C and B are destroyed in the product. Also, after heating, less different enzymes remain in milk. Soluble phosphate salts are converted into insoluble salts in it.
Storage: Sanitary Standards
After the initial processing, milk on the farm may remain for some time before being sent to the enterprises. To store this product on the farm so that its properties do not change, you need, of course, correctly. Otherwise, this product may simply not be accepted at the processing plant. For storage of milk on farms can be used:
tanks
tanks;
bathtubs;
jars.
Cooling is an important step in such a procedure as primary milk processing. And the storage of this product should be carried out subsequently, of course, at low temperatures.
Of course, on farms, among other things, they also comply with the exposure times of this product before being sent to the enterprise. According to the regulations, at a temperature of +8 ° the maximum shelf life of milk should not exceed 12 hours; 6-8 ° C - 12-18 hours; 4-6 ° C - 18-24 hours
What sanitary requirements must be observed on the farm
The product shipped from the farms must therefore be fresh and clean. Milking and primary processing of milk must be carried out in accordance with all sanitary standards. Also, milk intended for sale must be whole and obtained from healthy cows. In order for this product not to be infected by any microorganisms or to absorb foreign odors, the following requirements must be observed during milking, primary processing and storage on the farm:
Also, the most strict veterinary control should be carried out on the farm. Diseases of cows on the farm should be identified on time.
In addition, under no circumstances should milking machines fall and the manure and litter be sucked into them. Of course, all machines for the primary processing of milk should be kept clean.