Study On Preparation,Separation And Biological Activity Of Lentinus Edodes Stalk Polypeptide

Lentinus edodes is a very important edible mushroom resource in the world.China is the world's largest producer and exporter of lentinus edodes,and it contains protein,amino acid,dietary fiber,vitamins and other nutrients required by the human body,as well as the important health function of lentinus edodes.The stalks of lentinus edodes account for 30% of the weight of lentinus edodes,due to the large amount of dietary fiber contained in the stalks of lentinus edodes,the taste of lentinus edodes is rough and difficult to chew,and it will affect the quality of mushroom products in the process of processing.Every year there are a large number of lentinus edodes stalk are disposed of as waste.Therefore,in order to make full use of lentinus edodes resources,it is of great significance to develop more lentinus edodes products by studying the polypeptides in lentinus edodes stalks.It can not only meet people's demand for healthy food,but also improve the utilization rate and economic benefits of lentinus edodes.In this paper,lentinus edodes stalks was used as the experimental material to extract and enzymatic hydrolyze the protein,to prepare polypeptides,and to isolate and purify polypeptides with different molecular weights,finally,the antioxidant and antibacterial activities of the purified polypeptides were studied.The main conclusions of the study are as follows:1.The selection method of ultrasonic extraction was studied for the proteins in the lentinus edodes stalks.According to the experimental results,the optimum technological conditions can be obtained as: power 100 w,temperature 50?,pH9.0,fuel to water ratio1:25,extraction time 1.5h,extracting 2 times,the final extraction rate of protein was 17.8%.2.Extract the neutral protease from 5 kinds of proteins,as the best enzyme,to enzymatic hydrolyze protein in the lentinus edodes stalks.The results showed the optimum conditions for enzymatic hydrolysis: pH6.0,temperature 55?,enzyme dosage 4000 u/g,time 2 h,measured peptide yield reached 19.98%.3.With ultrafiltration membrane separation with lentinus edodes polypeptide,get four components of lentinus edodes: component ?(> 10 kda),component ?(5-10 kda),component ?(1-5 kda)and component ?(< 1 kda).4.The scavenging and reducing power of ·OH and DPPH radical of 4 different components of lentinus edodes polypeptides were determined.The results showed that the 4 components of lentinus edodes polypeptides had strong scavenging effect,indicating that they were antioxidant active peptides.However,different molecular weight peptides have different antioxidant capacity,and their antioxidant activity is related to molecular weight.Among them,molecular weight <1KDa and 5kda-10 kda have stronger antioxidant activity.5.The antimicrobial activity of four components of lentinus edodes polypeptide was determined,the results showed that the four components of lentinus edodes polypeptide have certain bacteriostatic effects on staphylococcus aureus,escherichia coli,bacillus subtilis and salmonella.The inhibitory effect on salmonella is the strongest,followed by e.coli and staphylococcus aureus,while bacillus subtilis was the weakest,it has no inhibitory effect on penicillium and aspergillus flavus.