Effect of fatty acids on the flavor formation of fish sauce

An appropriate fish model helps track changes of lipid and fatty acid during fermentation. Here we selected three freshwater fish (Culter alburnus, Carassius auratus and Ietalurus Punetaus) as the fermentative materials of fish sauce due to their significantly different contents of lipid and unsaturated fatty acid. The electronic nose showed that the flavor profiles of sauce samples prepared with different fish were dramatically different. A total of 71 volatile compounds of fish sauce were detected by solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC/MS). Then nine key flavor compounds, including 3-methylbutanal, 3-methyl-1-butanol, 3-(methylthio)propanal, 1-octen-3-ol, phenylacetaldehyde, nonanal, dimethyl trisulfide, decanal and hexanol, were screened based on odor activity values. According to correlation analysis between fatty acid profiles and fish sauce aroma, possible pathways of oleic acid (C18:1) and linoleic acid (C18:2) oxidation were suggested: oleic acid undergone the auto-oxidation to mainly form 10- hydroperoxide and 11- hydroperoxide, and (or) secondary form 8-hydroperoxide, then converted to nonanal, octanal and decanal; linoleic acid undergone the enzymatic oxidation to form 10-L(S)-hydroperoxy-cis-9, trans-11-octadecadieuoic acid, then converted to 1-octen-3-ol.