Research On The Variations And Control Technology Of Fishy Odor For The Steamed Chinese Mitten Crab During Cold Storage (Eriocheir Sinensis)

Chinese mitten crab(Eriocheir sinensis),commonly known as hairy crab and river crab,with important nutritional value and delicious taste,it plays an important role in freshwater crustaceans in china.The market demand for Chinese mitten crabs is huge.According to statistics,the production of crab farming in China reached 759,900 tons in 2017.The delicious taste and rich nutrition of Chinese mitten crab is deeply loved by consumers.As an aquatic animal product,astringency is one of the main factors affecting its quality.The formation of astringency is complex and diverse,and the inherent astringency of aquatic animal products and the astringency of processing during processing,transportation,storage,etc.Aquatic animal products are active in tissues,fatty acids are easily oxidized,algae and microbes in the environment are the main factors that produce astringency.After being steamed,the Chinese mitten crabs will be aggravated after being placed in the refrigerator,which will affect the consumer’s preference.Taking this as a starting point,this study first analyzed the changes in astringency of steamed Chinese mitten crabs after refrigeration.On this basis,explore the relationship between the source of astringent substances and fatty acid.Finally,the method of vacuum packaging is used to control the astringency.The main research findings were as follows:1.Analyze fishy odor variations in edible parts of steamed Chinese mitten crab during cold storage.Fishy odor evaluation and principal component analysis(PCA)of odor profile,the key odor-active compounds were analyzed by HS-SPME-GC-MS,the odor components of steamed Chinese mitten crab abdominal meat,gonads and hepatopancreas were stored at 4 °C for 0,1,3 and 5 d.The results showed that in the fishy odor evaluation,fishy odor of the three edible parts increased significantly after cold storage;the electronic nose analysis showed a clear outline on the 3rd day;it was refrigerated for 0,1,3,and 5 d at 4 °C.44,45,50,and 54 volatile compounds were detected in abdominal meat.37,45,52,and 58 volatile compounds were detected in gonads and 52,61,62,and 57 volatile compounds were detected in hepatopancreas.The total amount of odor compounds in the three edible parts of steamed Chinese mitten crabs increased with increasing refrigerated time;The total amount of hexanal,heptanal,nonanal,(E)-2-octenal,and 1-octen-3-ol contributing to the fishy odor also increased and all of them showed significant differences on the 3rd day,the fishy odor increased significantly on the 3rd day.According to the OAV(odor activity value,OAV)value method,the degree of contribution to the odor of Chinese mitten crab during cold storage as follows hepatopancreas>gonads> abdominal meat.2.To explore the relationship between the change of astringency in the edible parts of steamed Chinese mitten crab and the fatty acid oxidation during cold storage.The thiobarbituric acid(TBARS)of steamed Chinese velvet crab meat,gonads and hepatopancreas were steamed at 0 °C for 1,3 and 5 days.Fatty acid content and fatty acid changes.The results showed that the TBARS values of the gonads and hepatopancreas There was a significant increase,and there was a significant difference on the 3rd day.There was no significant difference in the TBARS value of the flesh.After refrigeration,the fatty acid content of the three edible parts changed,and the total amount of saturated fatty acids and the total amount of polyunsaturated fatty acids showed a significant upward trend,and the total amount of monounsaturated fatty acids showed a downward trend.There is a significant decrease in C18:1n-9c,C20:1n-9,C20:4n-6 in fat,and it is oxidatively degraded during cold storage to form small molecular volatile odor substances,which may be the premise fatty acids for producing astringent substances.3.The steamed Chinese mitten crabs were vacuum-packed and refrigerated to explore the effect on the taste of steamed Chinese mitten crabs.The odor profile,thiobarbituric acid value and(TBARS)changes were analyzed by steaming the Chinese mitten crab,meat,gonad and hepatopancreas in vacuum packed at 4 ± 1 °C for 0,1,3,and 5 d.Headspace-solid phase microextraction-gas chromatography-mass spectrometry(HS-SPME-GC-MS)was used for volatile component analysis.The results showed that in the evaluation of astringency,the astringency of body meat and gonads did not increase significantly in the three edible parts after vacuum packaging,and the hepatopancreas increased the astringency on the 5th day;the electronic nose analysis showed no obvious The contours were differentiated;the TBARS values of body and gonads did not increase significantly after vacuum packaging,and the TBARS value of hepatopancreas increased with the increase of refrigerating time,indicating lipid oxidation in hepatopancreas.The vacuum-packed steamed Chinese mitten crabs showed no significant increase in the total amount of volatile substances in the body and the gonads as the refrigerating time increased.The total amount of volatile substances in the hepatopancreas increased continuously.Volatile substances in the body and gonads contributed to the astringency.There was no significant difference in the total amount of substances,and the total amount of volatile substances contributing to astringency in the hepatopancreas showed significant differences on the 3rd day.In general,vacuum packaging refrigeration can slow down the oxidation of fat and the astringency of astringency.