A pasteurizer is a sterilization method that heats a liquid to destroy harmful bacteria, and the taste of the liquid itself is not affected. At the end of the 19th century, pasteurization was already widespread. When the milk passes through a heated appliance, harmful microorganisms are eliminated, and thus the storage period of the milk is prolonged. The pasteurizer heats the mixed raw material to 68-70 ° C, and after maintaining this temperature for 30 min, it is rapidly cooled to 4-5 ° C. Because the fatal point of common bacteria is 68 ° C and 30 min or less, the mixed raw materials can kill the pathogenic bacteria and most non-pathogenic bacteria after being treated by this method; Cooling, sharp heat and cold changes can also cause bacterial death. The degree of pasteurization heat treatment is relatively low, and is generally heated at a temperature lower than the boiling point of water, and the heated medium is hot water. Different foods are pasteurized. In addition to liquid foods (juice, milk), acidic foods and canned jams, pasteurization technology also penetrates into other fields. For example, steam treatment will reduce the treatment of shelled oysters. The number of bacteria in oysters. It has the advantage of treating food at a lower temperature and in a shorter period of time, and maximizing the damage of the color, aroma, taste and nutrients of the food from long-term treatment at high temperatures. The following is an analysis of the sterilization methods applied in the pasteurization machine by Zhucheng Jianfeng Machinery Co., Ltd .:
1, sterilization storage technology
In the liquid medium, the biological effect sterilization of pulse discharge is utilized. The sterilization equipment is generally composed of two parts: a pulse discharge power supply for supplying energy and a sterilization chamber for directly sterilizing liquid materials. Working principle: when the pulse discharge is sterilized, the liquid material is placed as a dielectric. In the gap between the two electrodes of the sterilization chamber or continuously flowing through the two electrode gaps of the sterilization chamber, when the two electrodes are applied with a pulse electric field of a certain intensity and frequency, a strong biological effect is generated in the liquid material to kill the bacteria therein.
2, ultra-high temperature sterilization
With the advancement of technology, people also use ultra-high temperature sterilization (UHT ultra-high temperature instant sterilization, higher than 100 ° C, but the heating time is very short, the damage to the nutrients is small) to treat the milk. The shelf life of milk treated in this way will be longer. Most of the milk in carton packs we see is in this way.
3, electrolytic sterilization
In the conductive solution, due to the redox reaction caused by the exchange of electrons at the interface between the electrode and the solution, the reaction of this technology is divided into two types, one is caused by external electric energy, and the other is that there is no external power source. It is inspired by the external light, heat or other forms of energy.
4, AC sterilization
Generally speaking, it refers to a method of killing microbial bacteria through a low-frequency alternating current of several hundred Hz or less in a liquid material of a vegetable juice, and an extended use method thereof utilizes the thermal effect of alternating current, also called resistance heating technology, which utilizes continuous flow. The electrical resistance of the conductive liquid is heated to achieve sterilization.
5, laser sterilization
A laser is an electromagnetic wave, also an energy flow (photon flow), which is sterilized by the working principle of some special biological effects (chemical reaction, thermal effect, electronic effect, pressure effect, bio-stimulating effect) produced by the organism.
6, pulse glare sterilization
Sterilization is carried out using a strong white light flashing technique, which is generally used to treat surface sterilization of food products and to extend the shelf life of prepackaged foods of transparent materials.
7, microwave sterilization
The thermal effect of microwave energy: Under the action of a certain intensity microwave field, the insects and bacteria in the food will be heated by the microwave energy due to the molecular polarization phenomenon, thereby denaturation of the protein and loss of biological activity. The thermal effect of microwave mainly plays a role in rapid temperature sterilization;
The non-thermal effect of microwave energy: the high-frequency electric field also changes the membrane potential and polar molecular structure; the protein and physiologically active substances in the microorganisms are mutated, and the vitality or death is lost. It has played a special role in conventional physical sterilization in sterilization and is one of the causes of bacterial death.