Analysis of Volatile Compounds in Traditional Chinese Fish Sauce (Yu Lu)

Yu lu is a traditional Chinese fish sauce with a strong and distinctive odor. The volatile compounds in the fish sauce made from anchovy (Engraulis japonius) and the snakehead fish (Channa asiatica) were isolated by simultaneous distillation–solvent extraction (SDE) and analyzed by gas chromatography (GC) and mass spectrometry (MS). About 70 volatile compounds were identified, including 20 acids, 4 carbonyls, 14 nitrogen-containing compounds, 14 hydrocarbons, 8 esters, and 3 sulfur-containing compounds. The major contributors to the characteristic odor of the fish sauce are dimethyl disulfide, dimethyl trisulfide, propanoic acid, butanoic acid, 3-(methylthio)-propanol, 2-methylbutenal as well as some nitrogen-containing compounds. Nitrogenous and sulfurous compounds in the fish sauce made from anchovy were more abundant than the fish sauce made from snakehead, while snakehead fish sauce had a greater amount of volatile fatty acids. 3-(Methylthio) propanol could be another important contributor to the distinctive odor of fish sauce.