Principal Component Analysis and Cluster Analysis for Evaluating Free Amino Acids in Crayfish (Procambarus clarkii) from Different Co-culture Modes

To investigate the difference in the comprehensive quality of free amino acids (FAA) in crayfish meat from different co-culture modes, the FAA composition of crayfish tail meat from three representative co-culture modes in Xinghua city of Jiangsu province was determined, and the contribution of FAA to the taste of crayfish meat was evaluated by computing the taste active value (TAV). Comprehensive evaluation of FAA in crayfish meat was performed using principal component analysis (PCA) and cluster analysis. The results showed that 17 amino acids were found in crayfish meat from each co-culture mode, and the total amount of FAA was 21.80–27.11 mg/g. Arginine (Arg) was the most abundant FAA in all samples, accounting for 55.64%–67.76% of the total FAA, which was much more abundant than the other amino acids. Moreover, Arg contributed the most to the taste of crayfish meat. The TAV of the sweet amino acid alanine (Ala) and the bitter amino acid histidine (His) in crayfish were greater than 1 for all co-culture modes, indicating that both amino acids contributed to the taste of crayfish meat. The TAV of glutamic acid (Glu) as the amino acid with the strongest umami taste was greater than 1 only in crayfish meat from rice-crayfish mode with one-rice and two-crayfish in a field (RC2). Three principal components were extracted for the 17 amino acids, which cumulatively explained 89.937% of the total variance and could reflect the comprehensive information of amino acids in crayfish meat. The results of PCA showed that RC2 ranked first, and crayfish-crab mode (CC1) ranked last. The hierarchical cluster analysis divided crayfish meat from different co-culture modes into three categories. Similar results were obtained by PCA. This study demonstrated that the comprehensive quality of FAA in crayfish from rice-crayfish co-culture mode was better than that in crayfish from the other co-culture modes.