Headspace gas analysis of fish sauce

Volatiles from the headspace gas of fish sauce with no change in the pH (pH as is) were trapped in a Tenax TA column and analyzed by gas chromatography (GC) and GC-mass spectrometry (MS). Fish sauce was alkalized (pH 11.0) to enhance the release of nitrogenous and sulfurous compounds and was likewise analyzed. About 124 volatile compounds, including 20 nitrogen-containing compounds, 20 alcohols, 18 sulfur-containing compounds, 16 ketones, 10 aromatic hydrocarbons, 8 acids, 8 aldehydes, 8 esters, 4 furans, and 12 miscellaneous compounds, were definitely and tentatively identified. Detection of highly volatile nitrogenous and sulfurous compounds such as trimethylamine and dimethyl disulfide, which could not be easily detected by already existing methods, was enhanced after alkalization.