The effect of microwave on microorganisms is not only thermodynamic, but also non-thermodynamic. Non-thermodynamic effect refers to the physiological, biochemical and functional changes of cells without obvious changes in temperature. Microwave heating is a process in which alternating electromagnetic fields act on polar molecules such as water, protein and nucleic acid in materials, resulting in high-speed orientated transport of polar molecules. Motion and friction lead to sharp increase of internal temperature, which can modify or inactivate the molecular structure of proteins and nucleic acids in microbial cells and destroy microorganisms. At the same time, microwave can break up cell membranes and change the permeability of liposomes, and influence ion channels on which microbial cells exchange energy and information with the outside world to maintain their normal ecological activities. In addition, microwave has the characteristic of selective heating, and its effect on microorganisms is greater than that on microorganism growth medium. Some people have questioned whether there is non-thermal effect in the process of sterilization, but many experimental results have shown that there is non-thermal effect in microwave sterilization. Non-thermal effects quantify the enhancement of bactericidal efficacy. In order to ensure the microbiological safety of processed foods, only thermal effects are usually considered in the process design.
Principle of microwave sterilization: Microwave sterilization is an extension of microwave heating technology. It shows that the changes and reactions of cell physiological activities of organism after the interaction between microwave and organism and its basic unit-cell. Compared with pasteurization, microwave sterilization has the following remarkable characteristics:
Microwave sterilization is a physical sterilization method. It can kill harmful microorganisms such as bacteria, fungi and eggs, as well as viruses without adding chemical preservatives. In the process of killing harmful microorganisms, microwave sterilization will not pollute food residual toxicity or radioactive substances and is safe and harmless. It will not change the color, aroma and nutrition of food. At the same sterilization temperature, the time required for sterilization is short and no preheating is needed. For example, the killing time of E. coli is about 30S. Under the same sterilization conditions, the temperature of bacterial death is relatively low, and the sterilization effect is very significant.It can also carry out the whole sterilization on the surface of sterilized materials, greatly shorten the sterilization cycle and ensure the consistency of sterilization.Because of the simultaneity of sterilization in different parts of the material and the short sterilization time, it can avoid the influence of long-term heating on food quality, especially for food which is not suitable for sterilization at high temperature or for long heating time. For example: ginger powder with volatile spices, fresh and tender jellyfish with more water content, etc. Microwave sterilization can achieve the best results for materials that need sterilization as well as quality requirements such as color, fragrance and taste unchanged.
Bean & Nuts microwave roast and sterilization is to take food raw materials and processed products as the object, through sterilization and sterilization of microorganisms, which are the main factors causing food deterioration, to stabilize the quality of food, effectively prolong the shelf life of food, and thus reduce the number of harmful bacteria in food, so as to avoid the intake of live bacteria causing human (usually intestinal) infection or pre-produced bacteria in food. Toxins cause human poisoning.See the news list>>