Fresh milk complete set of equipment:
Storage tank - beverage pump - milk tank - hot and cold tank - cream separator - degasser - blending tank - homogenizer - ultra-high-temperature sterilization machine - plate heat exchanger - seed tanks - fermentation tanks - sterilization machine - automatic filling machine.
Cow - Grazing - Physiological factors - Milking - Milk production - Filtration - Instantaneous sterilization - Adding additives -Filling -Outer box -Advertising -Marketing.
Milk is a haven for microbial activity. According to the test at room temperature to the freshly milked milk without any treatment, after 12 hours, the microbial content of each milliliter of milk up to 114,000, to 24 hours per milliliter jumped to 1.3 million. This is why milk is prone to spoilage. Therefore, the milk sterilization and preservation technology is very important.
I, the sterilization of milk
In the production process, generally the freshly milked milk is first put into the milk tank, quickly cooled to inhibit the reproduction of microorganisms, prolonging the antimicrobial properties of milk for a longer period of time. The cooled milk needs to be sent to the factory in time for processing. That is, after filtration, purification, cooling, homogenization, sterilization and packaging and other processes, it will become the daily consumption of sterilized milk. Sterilization is an important process in the production of sterilized milk. Generally, it adopts pasteurization method (invented by German microbiologist Louis Pasteur in the 1850s, so it is named as such). There are two types of sterilization methods: low-temperature and high-temperature. Low-temperature sterilization method is to put the milk into a special pasteurizer, heating the milk to 62 ℃ ~ 65 ℃, maintained for 30 minutes; high-temperature sterilization method is to be heated to 73.8 ℃ ~ 76.6 ℃, the duration of 1 to 10 minutes, or 82.2 ℃, the time does not exceed 5 minutes. It is then rapidly cooled to 10°C. The purpose of cooling is to prevent the reproduction of residual sprouts and to maintain the quality of the milk. Alternatively, sterilizing can be achieved by using the earthen method. That is, after cooking over a high fire, a film of milk fat is quickly formed on the surface of the milk (subject to the milk not overflowing), as if a piece of cloth were covering the waves. Calculated from the formation of fat film, cook for another 15 minutes, you can achieve the effect of pasteurization method.
The sterilization of milk must be strictly controlled temperature and time. Otherwise, not only can not achieve the purpose of sterilization, but also destroy the nutrients of milk. This is because: First, a long period of high-temperature boiling will make the milk protein from the sol state into a gel state, resulting in a large number of proteins coagulation and precipitation; Second, the calcium in fresh milk is electrostatically combined with casein, the formation of the human body can be digested and absorbed casein calcium, and a long period of boiling milk and sterilization of milk compared to the casein is about 20% less calcium into more difficult to be absorbed by the human body digestive Calcium salts; three is a long time boiling will also make the lactose caramelization decomposition, low nutritional value; four is the destruction of a variety of vitamins, including vitamin A and other vitamins. Therefore, in principle, sterilized milk should be consumed directly without further boiling. If you need to add heat, just put the bag of cows in 50 ℃ ~ 60 ℃ of hot water for a few moments, it can be.
Two, sterilized milk preservation
Sterilized milk is not easy to keep at room temperature. Milk is most afraid of sunlight. In the sunlight, milk containing vitamin A, carotene, vitamin B1, vitamin B12 will be destroyed, so it is best to avoid light refrigeration. According to tests, milk cooled to 13 ℃, can be saved for 12 hours, therefore, the temporary non-drinking bags of sterilized milk, can be put into the refrigerator freezer, but do not put into the freezer. Because the milk once frozen, and then heated to dissolve, it will occur fat and protein separation, coagulation, precipitation, when the oil floating, milk flavor talk, nutritional value has been reduced. If you buy back the milk of individual households, after boiling and sterilizing, it is best to drink it all at once, and should not be kept. If you want to save, you can use a small mouth container, sealed storage, but should not be too long.
Now, the bags and bottles of milk sold in the market are made by dairy processing enterprises from dairy farms and cattle professional households to purchase fresh milk, after the sterilization process. Manufacturers use two methods to sterilize milk, one is the high-temperature instant heating method, the temperature of 135 ℃; two is
Pasteurization method. Pasteurization is the process of processing milk at 62-63 ° C for 30 minutes, or heating to 72-73 ° C for 20 seconds. If the packaging is well sealed, bottled milk can be stored at room temperature for several months to a year after leaving the factory, while bagged milk has a shelf life of 2-3 days in summer and 5-7 days in winter.
A dairy manufacturer surnamed Zhang, a senior engineer said, liquid milk according to the production process can be divided into sterilized milk, sour milk, pasteurized milk three. In terms of sterilization methods alone, there are "pasteurized milk" and "ultra-high temperature sterilization milk" two. In terms of packaging, can be roughly divided into plastic bags, Tetra Pak, cartons and plastic bottles of four; which Tetra Pak bottle is divided into pillow (bag) and brick (boxed) two kinds, all for the Swedish Tetra Pak company produced by the 5-7 layers of paper and aluminum foil composite composition of the packaging. According to experts, the shelf life of milk, drinking methods and packaging have a great relationship, different packaging and sterilization methods to determine the shelf life of milk.
Pasteurized (bagged/house-shaped) sterilized milk: also called pasteurized milk. Pasteurized for a few seconds at around 80°C, it is a "short-lived milk" that needs to be kept in a low-temperature refrigerator, with a shelf life of 1-7 days; when kept at a temperature of more than 4°C, the bacteria in the milk are still able to reproduce, so it cannot be kept for a long period of time at room temperature. Pasteurized milk includes three kinds of products: full-fat and partially skimmed, which are suitable for families who are quick to sterilize and buy more frequently.
Bagged milk is inexpensive and therefore suitable for delivery to thousands of households, becoming breakfast food for many families. The house-shaped fresh milk, which looks like a house, is packaged in light-proof and environmentally friendly paper materials, and adopts the internationally accepted "cold chain control method", which means that the whole process from milk extrusion to production, storage, transportation and sales is carried out under low-temperature conditions, with a preservation period of up to seven days. One of its characteristics is "fresh": from milk extrusion to product filling completed within 8 hours; the second is the production process is advanced, scientific, nutrient preservation, the nutritional indicators are higher than ordinary bagged milk. Strong flavor, rich taste of the house-shaped milk is fresh milk in the boutique, its price after a substantial adjustment began to approach the ordinary people. However, because of the price disadvantage, the house-shaped milk in a considerable period of time is still not able to replace the inexpensive bags of sterilized milk.
Ultra-high temperature (pillow bag/brick box) sterilized milk: also known as high temperature milk. Using instant ultra-high-temperature sterilization method, in a production line, the sterilization of packaged materials, box molding and packaging is completed at once, that is, from the package forming to the product filling process, are carried out in a sealed aseptic area. Tetra Pak Fresh cartons contain 5-7 layers of protective film to protect the vitamins in the milk from sunlight. Tetra Pak Fresh packaged UHT-sterilized fresh milk is "long-life" and has a long shelf-life, allowing consumers to buy it less frequently. The product itself does not require refrigeration and has a shelf life of 8 months at room temperature, but only if it is unopened. Once the package is opened, it should be refrigerated and consumed within 3-4 days. Tetra Pak Pillow Pack is economical and more suitable for carrying on the go.