Research on Quality and Flavor Characteristics of Five Kinds of Commercially Available Sour Fish Sauce in Qiandongnan

Five kinds of commercially available sour fish sauce were taken as the research object to clarify their quality and flavor characteristics. The physicochemical and nutritional indexes, free amino acids, and volatile components were analyzed. The results showed that the moisture, ash, total acid, amino acid nitrogen, reducing sugar, protein, vitamin C and fat contents in the five kinds of sour fish sauce were significantly different (P<0.05). In total, 17 free amino acids were detected, including 7 essential amino acids and 10 non-essential amino acids. The content of total free amino acids in the samples ranged from 7.954~14.998 mg/g. The total content of free amino acids in sample Z was the highest at 14.998 mg/g. The content of umami glutamic acid was the highest in the L sample, which was 4.689 mg/g, and the taste activity value (TAV) reached 15.63, which was much higher than that of other samples. The electronic nose results showed that the main volatile components of five kinds of sour fish sauce were nitrogen oxides, short-chain alkanes, inorganic sulfur compounds, alcohol ether aldehydes, and organic sulfides. Principal component analysis could differentiate between different sour fish sauces. In this study, 57 volatile components were detected in five kinds of sour fish sauce using gas chromatography-mass spectrometry (GC-MS), including 20 esters, 14 alcohols, 14 alkenes, 2 acids, 2 phenols, 3 aldehydes and 2 ketones. Using orthogonal least squares-discriminant analysis (OPLS-DA) and variable important projection (VIP) selection, eighteen key volatile aroma compounds, including zingalene, ethanol, ethyl cetanoate, ethyl linoleate, limonene, acetic acid, linalool, ethyl myristate, 4-ethyl-2-methoxyphenol, phenethyl alcohol, alpha-curcumene, methyl salicylate, β-sesquiphellandrene, citral, isoamyl alcohol, camphene, β-bisabolene and geraniol, were identified in the five kinds of sour fish sauce. In conclusion, the results provide a basis for the quality evaluation and comprehensive development of sour fish sauce.