Nuts, also known as chestnuts and Chinese nuts, are genus of the genus Chestnut. Fresh nuts are prone to germination, mildew and other phenomena during storage and transportation, and should not be stored for a long time. During the deep processing of nuts, more dehydration is required. Nuts are heat sensitive materials, and dry dehydration has a great influence on their sensory and nutritional quality.
Drying is an important food processing method and an effective method for prolonging the shelf life of fruits and vegetables. It can reduce the weight of vegetables and vegetables, reduce the volume, and facilitate transportation. It does not need to add preservatives, is convenient to eat and easy to preserve for a long time. At present, the methods for dehydration of fruits and vegetables mainly include hot air drying, microwave drying, heat pump drying and vacuum freeze drying. As a traditional dry method, hot air drying has long drying time and high processing intensity, which leads to problems such as browning of dried products and marked deterioration of characteristic flavor. Microwave dryer is a low-heat drying equipment that has developed rapidly in recent years. It is a high-tech joint drying technology that uses microwave energy to dry materials under vacuum conditions. It has the characteristics of high drying efficiency, low temperature, easy control and environmental protection, especially for The materials that are difficult to achieve in the traditional drying process can retain the original color and aroma and heat sensitive and bioactive components, overcome the shortcomings of hot air drying, and the product quality is obviously improved compared with hot air drying, and is close to freeze drying, most likely Part of the food drying replaces freeze-drying and can significantly reduce production costs.
Accelerate the drying phase and slow down the drying phase. Whether it is the accelerated drying stage or the slowing down drying stage, as the microwave power increases, the water loss rate curve of the nut nuts becomes steeper. The greater the microwave power, the shorter the time required to accelerate the drying phase. In the accelerated drying stage, the drying rate reaches the maximum value from the start of drying, the microwave is fully absorbed by the nut, the temperature of the shell and the nut are simultaneously and rapidly increased, and most of the water in the shell vaporizes and evaporates through the pores in the shell. Going out, but the water in the nuts is not able to evaporate in time due to the obstruction of the diaphragm and the shell in the nut, and still stagnates inside the nut, so that the internal pressure of the shell is higher than the external pressure. At this time, the evaporation of water in the shell becomes the main reason for the decrease in the moisture content of the nut. After that, as the water continues to evaporate, the diaphragm and the shell material become loose, the pores become larger, the pressure difference between the inside and outside of the shell increases, the crack appears and gradually increases, and the water in the nut passes through the pores and the fruit in the membrane and the shell. The shell cracks are largely evaporated and the nut nut drying rate continues to increase to a maximum. At this time, the evaporation of water in the nuts is the main reason for the decrease in the moisture content of the nuts. As the drying process continues, a large amount of water in the nuts is evaporated, and the nuts appear to shrink to a certain extent, which increases the difficulty of water migration and evaporation, and gradually reduces the rate of water loss.See the news list>>