The freeze-drying temperature of chicken is about fifteen degrees below zero. The * * * crystal point temperature slice of chicken freeze-dried chicken is about-15 degrees. When slow freezing is used, because of the low concentration of extracellular solution, crystallization occurs outside the cell first, and the water in the cell moves to the ice crystals that have already formed outside the cell, which makes the ice crystals larger in volume, irregular in shape and uneven in distribution. Large ice crystals are easy to cause mechanical damage to cells and tissues, and the quality of finished products becomes worse.

Temperature during quick freezing

When quick freezing is used, the advancing speed of ice layer in material tissue is faster than the moving speed of water, and the distribution of ice crystals is close to that of liquid water in food. The volume of ice crystals is small, which is beneficial to the quality of finished products. Quickly freeze the pre-frozen chicken, put it on the shelf and cool it to-65438 05℃, and continue to cool it for about 65438 0.5 hours.

At this time, the upper temperature is -3 1.5 degrees, the lower temperature is -34.6 degrees, and the feed temperature is -20.7 degrees, which can be considered as lower than the * * * crystal point temperature of chicken. Close the liquid inlet valve of the drying chamber, only refrigerate the water catcher, and at the same time, start emptying the drying chamber, electrify and heat the shelf, and the sublimation process begins.