The Study Of Letinus Edodes Vacuum Freeze-Drying Processing

Letinus edodes are nutritious which have high nutritional value and health effects. Letinus edodes have tender texture, and then their freshness decreased rapidly after harvest, which will lead to parachute, gill browning, fruiting bodies atrophy, affecting taste and commercial value,so it is not easy to keep in storage. Vacuum freeze-drying is a new drying technology,keep their color, aroma, taste and nutritional ingredients to a large extent , and completely dehydrated, rehydrate well.The article determined the eutectic point and eutectic point using fresh Letinus edodes as the material.It research the vacuum freeze-drying process on the base of new freeze dryer.Through analyzing the mechanism of vacuum freeze-drying process and the theory of heat exchange,it it defined the main factors of Letinus edodes vacuum freeze-drying process: material thickness, cooling rate, pressure and heating temperature by analyzing the vacuum freeze-drying process and mechanism. By single factor experiments and the four factors and five levels of the quadratic regression orthogonal experiment, analysing the model and t test analysis of variance, we got each factor antagonism the yield of starch size: cooling rate>drying chamber pressure> material thickness>heating temperature. Using SAS software to analysis the results of second rotation regression test and optimiz process parameters, we got the optimum conditions: drying chamber pressure 61.8Pa, heating temperature 61.7℃, pre-freezing rate of 2.58℃/min, material thickness of 6.78mm . Drying time 7.27h. At the same time, in order to verify the quality of dried Letinus edodes further and design reasonable dried parameters, the paper do the compared experiment of Letinus edodes which produced by different drying methods ,it found: vacuum freeze-drying are better than hot air drying in the aspects of sensory indicators, rehabilitation of water conditions and nutrient content.