Changes in Volatile Flavor Compounds in Sufu during Fermentation

Volatile compounds in samples collected at different stages during the fermentation of sufu were extracted and analyzed by solid phase micro-extraction(SPME) combined with gas chromatography-mass spectrometry(GC-MS). The results showed that 110 volatile compounds were isolated and identified, which included 41 esters, 19 aldehydes, 12 ketones, 12 alcohols, 9 acids, 9 hydrocarbons and 8 other compounds. Volatile composition differed significantly across various processing stages. More volatile compounds were detected as the fermentation proceeded. The relative contents of aldehydes were decreased significantly after Mucor fermentation, whereas the relative contents and kinds of esters and alcohols were increased. As the post-fermentation proceeded, the relative contents of aldehydes, acids and esters were increased gradually. Among these volatile compounds, caproaldehyde, 2-phenylethanale, nonanal, dipentene, ethyl caproate, ethyl phenylacetate, ethyl valerate, ethyl octanoate, 2-amylfuran and allyl methyl disulphide had an important contribution to the flavor of sufu during the fermentation process.