(1) Ultra-high pressure sterilization technology: food ultra-high pressure sterilization (high hydrostatic pressure sterilization) is a food medium that is packaged in a certain way, and then placed in a liquid medium (usually an emulsion of edible oil, glycerin, oil and water), 100~ After a certain period of time under a pressure of 1000 MPa, it is required to achieve the sterilization requirements. The basic principle of sterilization is the lethal effect of pressure on microorganisms, mainly by destroying the activity of cell membrane inhibitory enzymes and affecting the replication of genetic material such as DNA. Under the pressure of 400-600MPa, bacteria, yeasts and molds can be killed, and the bad changes caused by general high-temperature sterilization can be avoided. Therefore, the inherent color, aroma and taste of the food can be better maintained, and the shelf life can be extended. effect.

(2) Low-temperature sterilization: Low-temperature sterilization is a heating method for partially sterilizing microorganisms present in foods. A temperature of 100 ° C or less is usually used. Since the bacteria in the food remain after the low-temperature sterilization, in order to prolong the shelf life of the product, processing techniques such as refrigeration, fermentation, addition of additives, and deoxidation are used. This method is mainly applicable to acidic foods with a pH below 4.5 and foods that are significantly deteriorated by heat treatment. In recent years, this method has also been applied to milk and commodities with a short shelf life.

(3) Pasteurization: Pasteurization refers to a relatively low temperature heat treatment method, generally carried out at temperatures below the boiling point of water. It is an ancient technology, pioneered by the 19th century French doctor Pasteur, and still has a certain application value.

Pasteurization is the earliest method of sterilization, using hot water as a heat transfer medium. The sterilization conditions are 61-63 ° C, 30 min, or 72-75 ° C, 10-15 min. When heating, it should be noted that the surface temperature of the material is 4~5 °C lower than the internal temperature; in addition, when the surface generates bubbles, the foam part is difficult to meet the sterilization requirements. This sterilization method, because of the long time required, the production process is not continuous, and it is easy to change certain heat-sensitive components by heating for a long time, and the sterilization is not ideal. It is rarely used in large and medium-sized food factories.

(4) Ultra-high temperature instant sterilization: Ultra-high temperature sterilization is referred to as UHT sterilization. Generally, the heating temperature is 125-150 ° C, the heating time is 2-8 s, and the sterilization process of the product after the heating reaches the commercial sterility requirement is called UHT sterilization. This sterilization method can achieve the purpose of sterilization in an instant, and the sterilization effect is particularly good, and the sterilization requirement can be almost reached or close to the sterilization, and the chemical change caused is small. It has the advantages of improving processing capacity, saving energy, reducing equipment volume, stabilizing product quality, and implementing equipment in-situ non-disassembly cycle cleaning.

(5) Microwave sterilization: Microwave sterilization is the process of microwave treatment of food, so that the microorganisms in the food lose vitality or death, thereby achieving the purpose of extending the storage period. On the one hand, when the microwave enters the inside of the food, the polar molecules in the food, such as water molecules, constantly change the polarity direction, causing the temperature of the food to rise sharply to achieve the sterilization effect. On the other hand, the non-thermal effect of microwave energy plays a special role in conventional bactericidal sterilization. Bacterial cells change their biological arrangement and movement law under the action of a certain intensity microwave field, while absorbing microwave energy. When the temperature is raised, the protein in the body is simultaneously subjected to both non-polar thermal motion and polar rotation, causing the spatial structure to change or destroy, resulting in protein denaturation and ultimately loss of biological activity. Therefore, microwave sterilization mainly causes the mutation and destruction of proteins and physiologically active substances in microorganisms under the action of microwave thermal effect and non-thermal effect, thereby causing cell death.

(6) Ultraviolet sterilization: The bactericidal action of ultraviolet rays is to promote the degeneration of cytoplasm. When the microbial cells inhale ultraviolet rays, the cytoplasm is denatured due to chemical changes in intracellular components, particularly nucleic acids, protoplasmic proteins, etc. due to photochemical action. In particular, it inhibits DNA replication and cell division, causing microbial cells to be injured or even killed. The ultraviolet ray has the strongest bactericidal effect at a wavelength of 250 to 260 nm.

(7) Ozone sterilization: Ozone is a lavender, special fishy smell gas that exists at room temperature and freezing temperature. It dissolves partially in water and increases solubility with decreasing temperature; at normal temperature Self-degradation produces a large number of free radicals, most notably hydroxyl radicals, and thus has strong oxidizing properties.