Study On The Quality Evaluation Of Crayfish And Its Processing And Storage Characteristics

Crayfish(Procambarus clarkii)is one of the most important economic freshwater shrimp resources in China,which is favored by consumers because of its delicious meat and unique flavor.However,due to the differences in production regions and growing environments,the quality of crayfish cultivated in different production regions and growing environments are also different.With the rapid development of the crayfish industry,it is urgent to study and compare the differences in nutritional quality and flavor quality.In addition,processing and storage are both extremely critical steps in the sales process of crayfish.Therefore,it is necessary to explore the processing and preservation methods of crayfish,which would provide some references for the quality assurance of fresh crayfish storage and processing links.This paper studied and compared the nutrient and flavor components of female and male crayfish muscles in different production areas(Jiangsu,Anhui,Hubei)and growing environments(rice-field,lake,and pond).In addition,this article explored the effects of different processing methods(steaming,boiling,frying,high temperature)on the quality of crayfish,as well as the quality changes of alive and dead crayfish during refrigerated storage(4℃)and ice storage(0℃)storage.The main conclusions were as follows:(1)The nutritional quality of crayfish from different producing areas and growing environments was different to some extent.From production regions,Jiangsu crayfish had the highest essential amino acid index and fatty acid nutritional value,and it was rich in iron and manganese.Anhui crayfish had higher protein content,lower fat content,and higher nutritional value of protein and fatty acid.Hubei crayfish had the highest meat content,but the lowest nutritional value of protein and fatty acid.From the perspective of growing environment,the fatty acid nutritional value of crayfish in rice-field was low.Lake crayfish were high in protein and low in fat,but had the lowest essential amino acid index.Pond crayfish had the highest meat content,nutritional value of protein and fatty acid,and the content of various mineral elements was higher.(2)A total of seven categories of volatile substances were detected in the crayfish muscle of different production regions and growing environments:hydrocarbons,alcohols,aldehydes,ketones,esters,oxygenated compounds and other compounds.Among them,the content of aldehydes was the highest.From producing area,Anhui male crayfish had a unique odor,and the free amino acid data showed that the taste of Jiangsu and Anhui crayfish were richer.In terms of the growing environment,the odor of pond female crayfish was special,and lake crayfish had the least earthy smell,while the crayfish in rice-field had a fresher and sweeter taste.(3)Four processing methods of steaming(100℃),boiling(100℃),frying(160℃) and high temperature(121℃)were used to treat crayfish,and the optimal processing time was determined to be 8 minutes,6 minutes,4 minutes and 3 minutes,respectively.Various physical and chemical indexes showed that the total number of colonies of crayfish muscle in the four groups was in line with national standards.The crayfish treated by steaming and boiling had the best taste and texture,good hardness and chewiness,the lowest cooking loss rate and the degree of fat oxidation.After frying,the cooking loss rate and fat oxidation degree were the highest,and the quality of crayfish muscle was worst treated by high temperature.(4)The quality changes of alive and dead crayfish under refrigerated storage(4℃) and ice storage(0℃)were studied.The results showed that the total number of colonies,TVB-N content,TBA value,b~*value andΔE~*value of alive and dead crayfish under the two storage conditions increased significantly,and the p H value firstly dropped and then rose.Moreover,sensory score,total sulfhydryl content and L~*value were obviously decreased.In Summary,the shelf life of alive and dead crayfish under refrigerated storage had significant differences(8 days and 4 days,respectively),while the shelf life of alive and dead crayfish under ice storage ice storage had a similar shelf life(12 days and 11 days,respectively).