Abstract: In order to study the flavor characteristics of fish sauce produced in different areas, modern flavor analysis techniques such as headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), electronic nose, headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), amino acid analyzer and sensory quantitative description analysis (QDA) were used to analyze the volatile and nonvolatile flavor compounds of fish sauce from Shantou and Dongguan, Guangdong province and Fujian province in China as well as Thailand and Vietnam. Their relative odor activity values (ROAVs) were calculated as well. The results showed that GC-IMS and electronic nose could identify the differences in the volatile flavor compounds of samples from different regions. According to QDA, fish sauce from Thailand, Vietnam and Shantou had overall similar volatile flavor components, while they were quite different from those from the other two regions. Totally 37 flavor compounds were identified by GC-IMS, including aldehydes, alcohols, esters, acids and sulfur compounds. In addition, 47 volatile compounds were identified by HS-SPME-GC-MS. Volatile acids accounted for 78.13% and 42.92% of the total volatiles in Shantou and Vietnam fish sauce, respectively. Nitrogenous compounds account for a large proportion of the total volatiles in Vietnamese fish sauce. The content of alcohols was the highest in Fujian fish sauce and the lowest in Vietnam fish sauce. The major flavor components in Thai fish sauce were aromatic substances. Nitrogenous compounds (pyrazines and furans) and esters were the most abundant in Vietnamese fish sauce as the characteristic flavor compounds. Shantou fish sauce had the highest content of sulfur compounds, contributing to the characteristic flavor of Shantou fish sauce, including methyl sulfide and 3-methylthiopropionaldehyde. Amino acids were the precursors of the volatile flavor compounds. The total content of free amino acids was ranked as follows: Vietnam fish sauce > Shantou fish sauce > Thailand fish sauce > Fujian fish sauce > Dongguan fish sauce. However, the proportion of delicious amino acids in Dongguan fish sauce was the highest, with glutamic acid accounting for 93.35% of the total amount. Thailand fish sauce had the highest proportion of sweet amino acids. The content of sulfur-containing amino acids and taurine in Shantou fish sauce was the highest. The difference in the contents of free amino acids may account for the difference in characteristic volatile flavor compounds from another perspective.

Key words: fish sauce; characteristic flavor; gas chromatography-ion mobility spectrometry; solid phase microextraction-gas chromatography-mass spectrometry; free amino acids