The principle of sterilization is within a certain temperature range, the lower the temperature, the more slowly the bacteria reproduce, the higher the temperature, the faster the propagation. But when the temperature is too high, the bacteria will die. Different bacteria have different optimum growth temperature and heat and cold tolerance ability. In fact, the use of the pathogen is not very heat resistant characteristics, with appropriate temperature and heat preservation time, it will kill all of them. But after the PAP, still retain a small part of harmless or beneficial, more heat resistant bacteria or bacterial spores.

The production of the process of the method of the sterilization of the beer is from Pasteur's solution to the beer. At that time, the French wine industry is facing a headache problem, that is, the beer will become sour after brewing, can not drink. And the phenomenon of this kind of acid change often occurs. Pasteur was invited to study the problem. After a long period of observation, he found that the culprit is lactic acid bacteria lactic acid bacteria. Beer is a paradise for the growth of lactic acid bacteria. A simple way to boil is to kill the bacteria, but the beer is boiled down. Pasteur try to use different temperatures to kill the lactic acid bacteria, but will not destroy the beer itself. Finally, Pasteur's research results are: the temperature of 50~60 degrees Celsius to heat beer for half an hour, you can kill the lactic acid bacteria and spores, and do not have to boil. This method saved the wine industry in France. This kind of sterilization is also known as "the process of"". The milk should be kept at a temperature of about 4 degrees Celsius, and can only be kept for 3~10 days, up to 16 days.

Sterilization methods: today's use of a wide variety of procedures. "Low temperature long time" (LTLT) treatment is a batch process, and now only a small dairy plant used to produce some cheese products. "High temperature and short time" (HTST) treatment is a "flow" process, usually in the plate heat exchanger, is now widely used in the production of drinking milk. Products obtained by this way are not sterile, that is, there are still micro-organisms, and in the process of storage and processing need to be refrigerated. "Fast sterilization" is mainly used in the production of yogurt dairy products. At present, there are two kinds of international common high temperature sterilization method:

One is to heat the milk to 62~65 degrees Celsius, to maintain 30 minutes. Using this method, can kill milk in a variety of pattern of growth of pathogenic bacteria, sterilization efficiency can reach 97.3%~99.9%, after disinfection residual is only part of the thermophilic bacteria and heat-resistant bacteria and Bacillus etc., but these bacteria most is lactic acid bacteria, lactic acid bacteria not only harmless to people but is good for your health.

Second ways to heat the milk to 75~90 degrees, heat preservation 15~16 seconds, the sterilization time is shorter, the work efficiency is higher. But the basic principle of sterilization is that the pathogen can be killed, the temperature is too high, but there will be more nutritional losses.

The development process: in early 1935, Zandehansen began manufacturing tunnel pasteurization machine. Although has experienced more than half a century of practice, but today's Zandehansen still is a young, powerful, rich innovation company [2].

This is due to Zandehansen in nearly ten years and continue to develop new sterilization results. Both to meet the external market demand, but also pay attention to the development of their own models, thus promoting the development of Zandehansen sterilization machine, today's pasteurization machine like is a leap, though it only a few steps, but it has from the structure of the traditional jumped out. Here are some of the steps in development:

1989: the first through a personal computer to run real-time control of the unit.

1994: centralized heat exchanger supply system -- the concept of a single heat exchanger.

1997: bottom trough pasteurization machine -- tunnel pasteurization machine a new Daizandehansen.

In the second half of 1996, the first slot type sterilization machine was assembled (officially put into operation in June of 1997). It opens up a new structure of the PAP, which reduces the amount of water to the lowest point. The system is equipped with a cushioning system that optimizes the configuration of cold and heat energy, and does not use any of the valves.

The principle of the bottom slot type sterilization machine embodies the concept of a single heat exchanger, and the centralized heat exchanger supply system is fully utilized. This design is based on general modular structure, using standard fabrication methods, you can also adjust to other regional, this both normative and flexible characteristics not only to Zander Hansen, and to the user are is high beneficial, shorten the manufacture, delivery and installation.

Bottom tank pasteurization machine is centralized heat exchange supply system the main models, and can fully show the excellent performance of the pasteurization unit control -- a theoretical index all have reached here. Only when there is no other possibility, use clean water, overflow system in this way, compared with the traditional pasteurization machine, can reduce the water consumption of 40% ~ 35%. Bottom tank pasteurization machine using an automatic filter to replace the traditional manual double screen, this can not only strengthen the strength of machines, and simplify the machine structure.

Application: for a sterilization of milk, can kill pathogenic bacteria harmful to health and can make the milk quality change as little as possible. A method that is based on the high temperature resistance of Mycobacterium tuberculosis heat death curve and milk quality in most susceptible to thermal effect of cream separation thermal destruction of the curve of the difference principle, in the low temperature for a long time or high temperature for a short time under heating treatment is carried out on the. Among them, in 30 minutes at the temperature below 60 DEG C heating mode, as low-temperature sterilization standards, widely used as early as the world. The use of high temperature treatment on milk quality, although somewhat affected, but can enhance the sterilization effect, this method is called high temperature sterilization (sterilization), which is more than 95 DEG C heat for 20 minutes. In addition to milk pasteurization, can also be used in fermentation products.

Usually, bagged milk on the market is the use of pasteurized production. Factory fresh milk, low temperature treatment, and then using the method of sterilization. Packaged milk produced in this way can usually be stored for a long time. Of course, the specific processing process and process to be more complex, but the general principle is that.

It should be noted that it is not safe to drink fresh milk (which is just out of milk), because it may contain harmful bacteria that are harmful to our health. Another point is that the PAP is not a panacea, after the treatment of the milk still need to be stored at a lower temperature (generally <4 degrees Celsius), or there is a possibility of deterioration. So many methods of selling bags of milk on the market are not standardized.

The world consumes most of the varieties of milk is pasteurized milk, Britain, Australia, the United States, Canada and other countries pasteurized milk consumption accounted for more than 80% of liquid milk, varieties have skimmed, semi skimmed or whole. In the U.S. market, the actual almost all of the milk, but also large packaging (1 liters, 2 liters, 1 gallons), the public on the supermarket once bought enough milk to drink a week. There are few market sterilized pure milk sold, some small towns do not buy.

Pasteurized pure milk preserved natural nutrition and flavor of milk, is one of the best in all varieties of milk. In fact, as long as the pasteurized milk at 4 degrees Celsius temperature preservation, the breeding of bacteria is very slow, the nutrition and flavor of milk can be maintained in a few days.

At present in the market pasteurized machine mainly for commercial purposes, and Pap sterilization is the international general standards on sterilization, in many large enterprises are in use, now on the market of pure milk, other flavors of yogurt are after pasteurization. At any time the development of green health food, pasteurization machine now in many small farms are used, small dairy farms use is 100 liters or 200 liter, mainly making pure fresh milk to the market distribution. Now the pasteurization machine is equipped with a cooling water circulation system, usually of refrigeration has two, a is: compressor refrigeration, the refrigeration speed fast, the effect is good, a refrigeration is cold water refrigeration cycle is mainly cooling method of the logistics, to talk about cost is much lower.

Process: pasteurization machine is is temperature control instrument set pu value to the transformation curves of the actual control temperature of each temperature zone sink, through for detecting the temperature of the precise control of the temperature zone temperature changes. The main drive motor drives the upper and lower two layers of the bottle conveying chain network material after heating by preheating three temperature zones A, and the sterilization of the two temperature zones and three temperature zones gradually cooling and cooling process.