Origin Traceability Of Chinese Mitten Crab Based On Amino Acids And Fatty Acids

Chinese mitten crab,also known as hairy crab and river crab,is one of the main freshwater economic crabs in China.It is widely distributed in China's coastal rivers and lakes,mainly including Liaohe River,Yellow River and Yangtze River.Chinese mitten crab is a kind of high-quality aquatic product loved by consumers because of its fresh and tender meat,excellent flavor,rich in amino acids,fatty acids and other nutrients.Due to the different nutritional quality of river crabs from different producing areas,there is a phenomenon of shoddy quality in the current market,and the existing technical methods are difficult to distinguish simply and effectively.In this paper,the regional differences of Eriocheir sinensis in Yangcheng Lake,Songjiang kunmao,Songjiang Jinmao,Songjiang Damao and Chongming Chenjiazhen were compared by measuring the content of rich amino acids and fatty acids in Chinese mitten crab.The origin traceability model of systematic cluster analysis,linear discriminant analysis and principal component analysis was established to distinguish the Chinese mitten crab in different regions The results are as follows:(1)A HPLC method was established for simultaneous determination of 17 amino acids in muscle tissue of Chinese mitten crab.In this method,o-phthalaldehyde(OPA)and 9-fluorenylmethylchloroformate(FMOC)were used as pre column derivatization reagents,and 3,3'-2-thio-2-propionic acid(DTDPA)was used to protect cysteine.The amino acids were separated on advancebio AAA column,derivatized on-line by automatic injection program,gradient eluted,detected by UV detector and quantified by external standard method.The results showed that 17 amino acids had a good linear relationship with their peak area in the range of 1?g/ml to 200?g/ml,and the linear correlation coefficient(R~2)was between 0.9973?1.0000.The detection limit was0.12?0.30?g/ml,and the average recovery rate of standard addition was 82.6%?115.2%under the three concentration of 2.30 mg/g,4.60 mg/g and 6.90 mg/g,and the relative standard deviation(RSD)was 0.7%?4.8%(n=5).The method is simple,qualitative,reliable and accurate in quantitative.It can be used to quantify cysteine and other primary and secondary amino acids in Chinese mitten crab.(2)A gas chromatography(GC)method was developed for the determination of fatty acids in muscle tissue of Chinese mitten crab.Chloroform methanol(1:1,v/v)was used as the extraction reagent,2%sulfuric acid methanol solution was used as the methyl esterification reagent,and dm-2560(100 m)was used according to the temperature programmed conditions×0.25 mm×zero point two zero?m)37 kinds of fatty acids were separated by capillary column,detected by FID and quantified by external standard method..The correlation coefficient(R~2)of 37 fatty acids was 0.01 mg/100g?0.02mg/100g and 0.04mg/100g-0.06mg respectively,with the correlation coefficient(R~2)between 0.9981-0.9999/The results showed that the recovery of the standard addition was 76.0%?97.5%at the three levels of 1?2?10 mg/100g,and the relative standard deviation(RSD,n=5)was 3.31%-7.90%.The method was applied to the determination of fatty acids in the muscles of Chinese mitten crab.31 kinds of fatty acids were measured in muscle.The length of carbon chain was between 12 and 24,and the total content of fatty acids reached 281.03 mg/100g,among which oleic acid,DHA,EPA are the main fatty acids in the muscle of Chinese mitten crab.The method is simple to operate,the reagent and sample are less,qualitative,reliable and accurate in quantity.The method is sensitive and high energy to detect more fatty acids.It is suitable for the rapid detection of fatty acid composition and content in the muscles of Chinese mitten crab.(3)The feasibility of tracing the origin of Chinese mitten crab by amino acid content was discussed.The origin traceability models of Chinese mitten crab in Yangcheng Lake,Songjiang Damao,Songjiang kunmao,Songjiang Jinmao and Chongming Chenjiazhen were established.The contents of 17 amino acids in muscle,hepatopancreas and gonad of Chinese mitten crab in five regions were analyzed by one-way Anova and Duncan multiple comparison method The results showed that the contents of 17 kinds of amino acids in the three tissues of Chinese mitten crab were different in five regions;the preliminary cluster analysis of amino acids in the three tissues was carried out by using the method of systematic cluster analysis,and the cluster results showed that the samples from five regions were not well clustered;the muscle samples from five regions were analyzed by linear discriminant analysis 66.7%,66.7%,66.7%,83.3%and 83.3%respectively.The overall initial discrimination accuracy was 73.3%and the cross validation discrimination accuracy was 56.7%.In addition to individual mistakes,hepatopancreas and gonad were classified well except for some mistakes;principal component analysis was used to select four principal components from muscle,with the cumulative variance contribution rate of 84.9%,and three principal components from gonad,with the cumulative variance contribution rate of 87.1%.The results showed that the samples from Chongming and other four areas could be separated,but the samples from Yangcheng Lake,Songjiang kunmao,Songjiang Jinmao and Songjiang Damao could not be separated.The results of principal component analysis of amino acids in tissues of Chinese mitten crab were not ideal.(4)The feasibility of tracing the origin of Chinese mitten crab by fatty acid content was discussed.The results showed that the fatty acid content in the three tissues of Chinese mitten crab was different in different degrees in five regions.The samples from five regions were preliminarily clustered by the method of cluster analysis.The clustering results showed that:except gonadal tissue samples,the clustering effect of the other two tissues was not ideal;through the linear discriminant analysis of fatty acid content,the samples of three tissues in five regions were all correctly classified,and the overall initial discriminant accuracy and cross validation discriminant accuracy were better;Five principal components were selected from three kinds of tissues by principal component analysis,and the cumulative variance contribution rates were 89.1%,90.6%and 84.4%respectively.The samples from five regions could be divided into five different regions by plotting the principal components of three tissues.(5)The effect of the combination of amino acids and fatty acids on the stability of the origin traceability discrimination model of Chinese mitten crab was studied.After combining the amino acids with fatty acids in three tissues,the clustering analysis of five regions was carried out,and the clustering result was the same as that of using fatty acids alone,which could not separate the samples from five regions;linear discriminant analysis has been used to classify the samples from five regions,which was the same as that of using fatty acids alone;principal component analysis Seven principal components were selected from muscle,hepatopancreas and gonad,and the cumulative variance contribution rate was 90.6%and 89.4%respectively.Eight principal components were selected from gonad,and the cumulative variance contribution rate was 88.4%.The principal components of three tissues were plotted as scatter plot,which could be divided into five different regions.