Characterization of volatile compounds and physicochemical properties of hongeo using headspace solid-phase microextraction and gas chromatography-mass spectrometry during fermentation

Changes in the volatile composition and some chemical properties of fermented skate, hongeo at different stages in its fermentation process were investigated using headspace solid-phase microextraction and gas chromatography-mass spectrometry. The result showed that a significant increase in pH, ammonia nitrogen, total volatile base nitrogen (TVBN) and trimethylamine nitrogen (TMAN) content during fermentation. A total of 208 volatile compounds, consisting mainly of hydrocarbons, alcohols, ketones, esters, amines, aldehydes, sulfur compounds, indoles, phenols, and other compounds, were detected and identified. Volatile compounds including amines, hydrocarbons, and alcohols were dominant in the unfermented hongeo samples, whereas pyrazines, indoles, phenols and sulfur compounds appeared from the early or middle stage and increased until the end of fermentation. The significant increase in abundance and relative content of volatile compounds at the initial fermented stage indicated that the metabolic activity of microorganisms plays an important role in the formation of the unique flavor. We present SPME/GC-MS as a useful tool for monitoring the volatile compounds of hongeo during fermentation, and provide important information for investigating the mechanism of unique flavor formation in hongeo products.

Automated summary

The study investigated the changes in volatile composition and chemical properties of fermented skate, hongeo at different stages of fermentation using headspace solid-phase microextraction and gas chromatography-mass spectrometry. The results showed significant increases in pH, ammonia nitrogen, total volatile base nitrogen, and trimethylamine nitrogen content during fermentation. A total of 208 volatile compounds were detected, with a dominant presence of amines, hydrocarbons, and alcohols in unfermented samples, while pyrazines, indoles, phenols, and sulfur compounds appeared from early to middle stages and increased until the end of fermentation. The study highlights the important role of microbial metabolic activity in the formation of unique flavors in hongeo products.