Research On Heat Pump Drying Process And Quality Control Technology Of Lentinus Edodes

Lentinus edodes is a kind of medicinal and food fungus with delicious taste and unique flavor.Fresh Lentinus edodes have high water content and are perishable.After drying,it inhibits the reproduction of microorganisms,is convenient for storage,transportation and sales,can extend the shelf life and increase the added value.This topic applies heat pump drying technology to the drying and processing of Lentinus edodes.The heat pump drying is highly efficient and energy-saving.However,after drying,the content of toxic substances such as formaldehyde in Lentinus edodes increases,resulting in a decline in product quality.Therefore,pretreatment is carried out before the drying of Lentinus edodes to study the formaldehyde of dried Lentinus edodes.Cadmium removal technology,explore the drying characteristics of Lentinus edodes heat pump,and finally determine the optimal process conditions for heat pump drying.It has a certain significance for the production of high-quality dried Lentinus edodes products.In this paper,Lentinus edodes are used as raw materials.First,the detoxification process of formaldehyde and cadmium in Lentinus edodes is explored and optimized,and lactic acid with a high removal rate of formaldehyde and cadmium is selected as the detoxifier.Then drying time,color difference value and rehydration ratio are used as the indicators,through response surface methodology to optimize the drying process of sliced??Lentinus edodes.Finally,qualitative analysis,sensory evaluation and quality evaluation of flavor substances were carried out on the dried Lentinus edodes products without pretreatment and lactic acid detoxification.The main findings are as follows:(1)The effects of different acid pretreatments on the removal of cadmium and formaldehyde were studied,and lactic acid was determined as an inhibitor for further experiment.The effects of p H,solid-liquid ratio,shaking time and shaking temperature on the removal rate of formaldehyde and cadmium were studied,and the optimal removal process was obtained through single factor and orthogonal experiment optimization:p H4.5,solid-liquid ratio 1:4,shaking temperature 35�C.Under these conditions,the removal rate of formaldehyde and cadmium were 88.06%and 79.57%respectively in heat pump drying.(2)Taking drying temperature,loading capacity and slice thickness as single-factor variables,and taking drying time,color difference value and rehydration ratio as indicators,the optimal technological conditions for heat pump drying sliced Lentinus edodes through single factor and response surface experiments were obtained as follows:drying temperature 60?,loading capacity 500 g/m~2,thickness3 mm.Under this condition,the drying time is 60 min,the color difference is 10.48,and the rehydration ratio is 7.15.(3)The effects of non-pretreatment and detoxification pretreatment on the flavor substances,sensory evaluation,nutritional components,shrinkage rate and rehydration rate of heat pump dried Lentinus edodes were compared.The main flavor substances in fresh Lentinus edodes,such as2-butanol,methyl-5-hepten-2-one,1-propanethiol,methyl 2-methylpropanoate,3-octanone and benzene acetaldehyde,were abundant in fresh Lentinus edodes,and their contents decreased greatly after drying.The content of dihydro-2(3h)-furanone,2-methyl-2-propenal,2-pentanone,hexanal,nonanal,cyclohexanone and other substances increased after drying.After detoxification pretreatment,the overall types and content of flavor substances,sensory evaluation scores,nutrient content,shrinkage rate and rehydration rate of dried Lentinus edodes samples were better than those without pretreatment.