Study On The Solar Drying Process And Dynamic Model Of Shiitake Mushrooms

Our country is the largest edible fungus cultivation country and export country,the fresh edible fungus has high water content,it must be dried in time after harvesting,otherwise it is easy to rot and deteriorate,which makes the product quality decline.At present,domestic edible fungus drying mainly uses coal combustion and electric heating to provide heat source,which leads to environmental pollution and energy shortage.In the face of increasingly serious environmental pollution and energy shortages,solar drying can not only solve the problem of environmental pollution and shortage of resources,but also improve the quality of dry products.In this study,fresh shiitake mushrooms were used as raw material for solar drying experiment,the effects of solar drying parameters(drying temperature,drying air velocity,drying capacity)on the drying characteristics,energy consumption and dry product quality of shiitake mushrooms were studied,the solar drying process of shiitake mushrooms was optimized and the dynamic model of solar drying of shiitake mushrooms was established.The drying time,drying energy consumption and dry product quality of three drying methods(solar drying,hot air drying,vacuum freeze-drying)were compared,and the suitable drying method in production practice was selected.In order to provide theoretical support and technical guidance for the industrial production of solar energy drying of shiitake mushrooms.The test results are as follows:1.The solar drying characteristic curve of shiitake mushrooms was obtained.The effect of different drying temperature(50,55,60,65?),drying air velocity(4,6,8,10 m/s)and drying capacity(2,4,6,8 kg)on dehydration characteristics of shiitake mushrooms were studied,the solar drying characteristic curve of shiitake mushrooms was obtained,the results show that:The higher the drying temperature is,the faster the drying rate is,the shorter the drying time is,when the drying temperature increases to a certain extent,the surface of shiitake mushrooms loses water too quickly and forms a hard shell,which makes shiitake mushrooms become a product with hard outside and soft inside,the drying rate slows down and the drying time increases in the later drying period;increasing the drying air velocity can increase the drying rate of shiitake mushrooms,the greater the drying air velocity,the less drying time;reducing the quality of shiitake mushrooms can improve the drying rate,the less the mass of shiitake mushrooms,the less the drying time.2.The suitable parameters of solar drying for shiitake mushrooms were determined.By single factor test and orthogonal test,the solar drying technology of shiitake mushrooms was optimized,the optimum drying process was determined by taking the drying time and energy consumption as the index.The optimum parameters of solar drying for shiitake mushrooms are as follows:drying temperature 55?,drying air velocity8 m/s,drying capacity 6 kg.3.A dynamic model for solar drying of shiitake mushrooms was established.According to the change regulation during solar drying of shiitake mushrooms,six classical mathematical models were fitted,a dynamic model for solar drying of shiitake mushrooms was established,R Square(R~2),Residual Sum of Squares(SSE)and chi-square(?~2)were selected as evaluation indexes of the model.The results show that the Midili Kucuk model is more relevant than other mathematical models in describing shiitake mushrooms change process of water ratio by solar drying.It is proved that the experimental value is basically consistent with the fitting value,under validation conditions,R~2=0.99918,SSE=4.90E-04,?~2=8.17E-05,the model fits well,can accurately reflect the variation of water content during solar drying of shiitake mushrooms.4.The effect of drying temperature,drying air velocity and drying capacity during solar drying on shrinkage,rehydration and hardness of dry products was studied,Which provided theoretical support for the industrialized production of shiitake mushrooms.The results show that:The higher the drying temperature,the greater the drying air velocity,the longer the drying time,the lower the quality of dry products.The concrete manifestation is:The shrinkage rate increases,the rehydration ratio decreases,and the hardness increases after rehydration.With the increase of drying amount,the quality of dried products first rises and then decreases,the smaller the drying amount,the faster the drying speed,the faster the water loss on the surface of shiitake mushrooms,and the easier the hardening occurs,resulting in the decrease of the quality of shiitake mushrooms,the increase of drying amount to a certain extent,the prolongation of drying time of shiitake mushrooms and the decrease of its quality.5.The drying energy consumption and dry product quality of three drying methods were compared,and the suitable drying method for shiitake mushrooms in production practice was selected.The quality of vacuum freeze-dried products is the best,but vacuum freeze-drying requires pre-freezing,long drying time,high energy consumption,refrigeration,heating and vacuum equipment are needed,so vacuum freeze drying is not suitable for large-scale promotion.Hot air drying is not suitable for large-scale promotion because dry products are of poor quality.The energy consumption of solar drying was the least,the quality of dry products is between vacuum freeze drying and hot air drying,the kinds and contents of amino acids are superior to those of vacuum freeze-drying.Considering the energy consumption of drying and the quality of dried products,solar drying is a suitable drying method for shiitake mushrooms in production practice.The results provide theoretical support and technical guidance for solar drying production of shiitake mushrooms,it has high practical value and wide application prospect.