Experimental Study On The Dewaxing Agent And Its Drying Improvement Mechanism Of Lycium Barbarum L.

Lycium barbarum L.is a medicinal and edible fruit with rich nutrition and abundant function active material.With the growth in the living standard,health food is widely required and the product quality is improving.The initial moisture content of Fresh Lycium barbarum L.is nearly up to 75%-80%,and fresh Lycium barbarum L.easily decays and breaks,so on the way of dehydration to prolong its shelf life and enrich the market of the fruit.With the expansion of Lycium barbarum L.producing,drying methods have been widely studied,but pretreatment method is less researched,so this paper do some research on physical and chemical pretreatment by the way of hot air drying.Pretreatment can decrease drying time and improve product quality,and then save energy and enhance product value.The main work and findings of the work are as follows:Hot air drying process:air temperature40?(6h)-50?(6h)-60?,relative humidity of 40%,and three layers material thickness.(1)Physical pretreatment methods:cutting along minor axis,cutting along major axis,punching small holes on the surface,cutting a incision.The drying time of physical pretreatment is shorten to 9-15h than water pretreatment 22h,the highest drying rate is up to 2.03kg/(kg-h)of cutting along major axis.Taking into consideration of polysaccharides content,color,rehydration ratio,the way of cutting a incision is better,polysaccharides content is 9.28%,color value of Lab is 29.51?27.62?17.52,rehydration ratio is 61.0%.(2)Chemical pretreatment is soaked by dewaxing agent solution.First,experiments analyze four factors,such as soaking time,solution concentration,solution type,solution PH.There is almost no influence on drying process of soaking time,solution mass concentration between 0.5%to 2%is the best.that drying time is shorten and product quality is better,weak alkaline solution obviously improve drying process,the best is 1%Na2CO3,the second is 1%NaHCO3,PH of treating solution is no certainly connection for drying process.Secondly,doing experiments of mixed solution with 2 kinds of agent gets that 1%Na2CO3 and 0.25%NaHCO3is better than 1%Na2CO3.Thirdly,comparing with drying process of summer fruit and autumn fruit pretreated of dewaxed agent,the result is that dewaxed solution pretreatment can short drying time of 2kinds of Lycium barbarum L.,because of the difference of growth period,drying time of summer fruit 20-22h is longer than autumn fruit 14-16h,and polysaccharides content of summer fruit is higher,color and rehydration is similar.(3)By comparing the SEM results of CHCl3,C6H14 and 1.25%Na2CO3 pretreatment,results show that the removing quantity of wax composition less influences on drying process,the types of pre-treating solution make large difference.Product of 1.25%Na2CO3 pretreatment still retain much wax crystals,then drying improvement do not remove wax,wax composition is stimulated by dewaxed agent becoming accumulative state,or dewaxing solution react with wax composition,leading that wax can't uniformly cover in cuticular and then improves the rate of water evaporation.