Application of "microwave drying" technology in food industry

The moisture content of food is usually 30% ~ 97% The application of microwave drying or microwave enhanced drying of food has broad prospects (1) microwave quick drying of food, such as drying vegetables into "dry vegetables" with moisture content less than 20% by microwave heating, can be more than ten times more efficient than traditional methods This method is not only suitable for vegetable drying, but also suitable for seaweed drying Under the microscope, it can be found that the tissue of microwave dried vegetables is close to that of fresh vegetables, but the drying time is shorter than that of freeze-dried vegetables Microwave can also be used for Zui final drying of fried products, which can not only save oil, but also get light and delicious food with low oil content It takes 5-8h to dry the dough with hot air to avoid crusting or cracking Microwave drying takes only 1-2h to dry the dough from the initial moisture content to 20%, and hot air is used to remove the moisture content, saving energy by 25% Microwave drying can also reduce the bacterial pollution, such as the combination of hot air and microwave drying garlic, hot air drying moisture from 80% to 10% (wet basis), then microwave drying to 5%, the total number of bacteria decreased by 90%, energy saving by 30% Under vacuum, microwave can deal with materials that will deteriorate or degrade when the temperature is higher than 40 ℃ (sometimes even 15 ℃) The vacuum drying oven can only conduct heat, usually without convection heating, and the drying time is very long The products of microwave vacuum drying include fruit juice, tea powder, enzyme, vegetables (mushrooms, garlic, soybeans, etc.) The cost of operation is between spray and freeze-drying In these systems, the material is usually paste material, which is laid on the conveyor belt and passes through a specially made tunnel (vacuum degree is 133.3-2666pa) to form a bubble Good rehydration performance (2) the combination of microwave and hot air drying can improve the quality of vegetable products, such as tomatoes, grapes, potato chips, carrots, etc the combination of microwave and hot air drying can improve the quality of the products, have good rehydration and low degree of shrinkage (3) microwave puffing drying of food, α - adding water to the powder of beans, cereals and potatoes, adding quantitative food additives to make it into shape, pre drying, and rapid drying of the product by microwave The protein based raw materials are added with starch fortifier, salt, seasoning and expanding agent, which are mixed, stirred, shaped and pre dried, and then heated by microwave The heated food will produce carbon dioxide and water vapor, so as to obtain soft and convenient food (4) both Glanz and LG microwave ovens provide microwave cookbooks for meat According to the cookbooks, meat, seafood and poultry can be processed to make all kinds of delicacies The average energy saving is about 60% The bone can reflect microwave Therefore, the meat is easier to ripen inside, not limited by the size and shape of the meat (5) microwave and infrared wave can be used to bake the food that is tender inside and scorched outside, which can be cooked by microwave first and then baked by infrared ray, such as roasted chicken with mushroom, roasted duck, roasted pig, etc (6) microwave sterilization and preservation of food in the microwave field, the polar groups of various macromolecules of microorganisms produce intense rotation and vibration, which make protein and nucleic acid produce variation, thus killing bacteria Generally, mold, yeast and bacteria can be killed when heated to 70-80 ℃, and sterilization can be achieved if microwave is used for 1 min For the spores of mould, for example, the spores of Penicillium can only be killed by conventional sterilization at 68-71 ℃ for 20 minutes, while the satisfactory results can be obtained by microwave sterilization at 68-71 ℃ for 2 minutes For example, microwave is used to sterilize, mould proof and keep the moon cake fresh, which has achieved good results, and the imported "preservative" is no longer needed Good results have been achieved in the sterilization of soybean powder, chicken essence and red heart sweet potato