What about the fresh milk pretreatment process
People have higher and higher requirements for the quality of fresh milk. In order to ensure the quality of fresh milk, fresh milk should go through the following pretreatment processes.
1. Fresh milk purification and filtration experience fresh milk must be filtered immediately after collection, its purpose is to remove impurities in the milk and reduce microorganisms. In the general dairy, four layers of sterile gauze filtration, or two layers of gauze stretched at the mouth of the milking drum, to prevent sundries from falling into the drum. In dairy, double bucket filter or double filter, or plate frame filter is used. After continuous filtration of 50000-100000 liters, it should be replaced, cleaned and sterilized. Therefore, it is advisable to use two filters alternately. Filtered milk still contains small sundries, cells, bacteria, etc. For further purification. The use of centrifugal milk purification machine, its principle is the use of high speed and powerful centrifugal force, the milk will be thrown out, the impurities in the separation of the body, this purification method in 32℃ temperature is appropriate. Raw milk means fresh milk.
2.The acceptance standards shall be formulated according to the physical, chemical and biochemical characteristics of raw milk and shall be accepted according to the standards. General acceptance of milk collecting station according to its physical and chemical characteristics of visual and simple instrument measurement, namely in addition to sensory inspection, alcohol test and relative density test. Other tests such as milk fat percentage, dry matter and acidity were carried out at the dairy. The acceptance of raw milk should pay attention to the following items: fresh milk from healthy cows; Colostrum, dried milk and the first 2-3 milk shall not be received; No visible impurities; It has the taste and smell of pure fresh milk, without peculiar smell such as feed taste, bitter taste, bad smell, mildew taste and astringency taste. Milk should be a uniform, precipitation-free fluid; The color of milk shall be white or milky yellow, and shall not be any other color; Acidity does not exceed 20. T; Milk fat ratio not less than 3. 2%, non-fat dry matter not less than 8. 5%; No preservatives or additives shall be used, and no water or adulteration shall be allowed. The number of bacteria should not exceed 300,000 per milliliter. Alcohol test alcohol test is a very important and necessary test for milk acceptance. It can detect not only milk with acidity exceeding a certain standard, but also many abnormal milk (mastitis milk, salt imbalance milk and milk immersed in calcium chloride solution, etc.). The purpose of alcohol test is to test the protein stability of raw milk. The higher the stability of protein to alcohol, the better the thermal stability of milk protein, indicating that milk quality is fresh, can withstand heat treatment, so as to obtain higher quality dairy products, on the contrary, it is poor. ‘3. 1 Principle of alcohol test alcohol test is the use of alcohol on protein dehydration. A certain amount of milk showed dehydration stability to a certain concentration and amount of neutral alcohol, and the protein of Milk ⅱ was agglutinated and agglomerated due to alcohol dehydration. In the dairy industry, alcohol with a concentration of 68%-72% is often mixed with the same amount of milk. If it is stable, the thermal stability of milk protein is acceptable, and the acidity of the milk meets the quality requirements of raw milk, otherwise it is positive milk. There are several reasons for alcohol positive milk: First, the p H value of normal milk is 6. 4-6. 8, the average is 6. Around 6.