Microbiology and Chemistry of Fermented Fish

Abstract

SUMMARY The microbiology and chemistry of Thai fish sauce was investigated in relation to the development of flavor and aroma. Total viable count decreased steadily as fermentation time advanced. The counts were higher when media containing 10% NaCl were used than when media containing 0.5% NaCl were used. Approximately 70% of the bacterial isolates from a nine‐month‐old fish sauce were halophiles of Bacillus types. These bacteria produced volatile acids from cultures in a medium prepared by hydrolyzing rockfish (Sebastodes sp.) with a mineral acid. A diethyl‐ether‐ethanol‐soluble fraction contained the typical aroma of fish sauce. This extract could be separated further by column chroma tography (AGl‐X8, formate form) into a fraction containing amino compounds and a second fraction containing weakly acidic compounds. The amino acids, principally glutamic acid, histidine, proline, etc., and other amines were identified by thin‐layer chromatography. The identification of acidic compounds has not been completed.