Effect Of Low Salinity Seawater Temporary Cultivation On Quality Changes Of Chinese Mitten Crab

The Chinese mitten crab is an important freshwater cultured crustacean in China.It is popular with consumers for its high nutritional value,pleasant special smell and good taste.It is first output in the world's economic crab after 2005.With the capture of various technological problems in the Chinese mitten crab culture,the crabs in the autumn season have gradually entered the homes of ordinary people.In order to explore the relationship between low salinity seawater keeping and the quality changes of Chinese mitten crabs,this paper systematically studied the detection and analysis of low salinity seawater keeping for various quality indicators of Chinese mitten crabs.The main results are as follows:1.Effects of low salinity seawater keeping on the biological index and basic nutrient composition of Chinese mitten crab.(1)In the freshwater group,the Chinese mitten crabs began to die after two weeks raised.After three weeks,there were deaths in both groups,and the body weight decreased significantly,the meat collection rate decreased,and the holding period could not be continued.(2)The protein content in the muscles of both groups increased,and the body weight and edible parts of the Chinese mitten crabs in the freshwater group gradually decreased after being raised.The low salinity seawater stimulated the female crabs to increase water content and gain weight,after the first week,Weight loss,moisture drops.(3)The two-week holding period of the seawater group increased the edible parts significantly,stimulated the development of the gonads,and increased the yellowing rate.2.Artificial sensory evaluation and the method of intelligent customs clearance evaluation.The effects of low salinity seawater conservation on the evaluation of the taste,smell and color of Chinese mitten crabs were studied.(1)During the holding process,the umami and sweet taste in the muscles of Chinese mitten crabs are the two most significant differences.However,with the increase of the length of holding time,the increase in the aftertaste makes the sense officials reduce their preference.After the raised period,the savory and sweet taste of Crab was increased.Compared with the crabs that had not been raised,the flavor was even more prominent.(2)The soil smell,fish smell,meat aroma,and clear scent in crab muscle are the four most responsive odors.After being raised,the muscles of the river crab after being raised have reduced soil odor and fishy taste and increased their liking.The purpose of removing bad smells is to remove the bad smell,crab smell,jellyfish taste,meat smell,and oily taste.Respond to the larger four odor types.(3)Principal component analysis of electronic tongue of Chinese mitten crab in low-salinity seawater retention process.The figure shows that the female crab seawater group is better differentiated from the non-suspended crab product.Weeks are better separated from the unscheduled and first week odour profiles,suggesting that the muscles of the stored crabs can be distinguished from the unreserved crab muscles.For the principal component analysis of electronic tongue of crab paste,it can be seen that the odor profile of seawater group and freshwater group can be better separated,and the second three weeks of crab yellow can be better separated from the non-holding and first week taste profile.The difference in electronic principal component analysis of the nose is smaller than that of the electronic tongue.(4)The effect of low-salinity seawater conservation on the chromatism of Chinese mitten crab showed that the redness of crab shells of the Chinese mitten crab after raising was increased,the crab redness was increased,and the crab paste brightness was increased.3.Effects of low-salinity seawater conservation on free amino acids,taste nucleotides,and volatile flavor compounds of Chinese mitten crab(Eriocheir sinensis).The results showed that:(1)The results of free amino acids and taste nucleotides showed that seawater in freshwater crabs,four free amino acids,alanine,glycine,arginine,and valine,accounted for more than 50%of sweet amino acids,and the proportion of amino acids for umami taste increased with temporary keeping duration.(2)The results of EUC indicated that the umami taste of the low-salt seawater group gradually increased during the holding process,and that of the freshwater group was higher than that of the low-salt seawater group at the second week;the result of the TAV value showed that the low salt was passed for 1-2 weeks.Degree seawater raises the muscles and sweetness.(3)The results of volatile components show that with the increase of holding time,the total amount and species of volatile components are reduced.In particular,the content of soil odor caused by hexanal,heptanal,octanalis reduced.To achieve the purpose of removing earthy smell.