Abstract: Volatile compounds in samples collected at different stages during the post-fermentation of Aspergillus-type douchi were analyzed by solid phase microextraction (SPME) combined with GC-MS and quantified by area normalization method. The major volatile flavor compounds during the whole post-fermentation process included 5 alcohols, 7 esters, 3 aldehydes, 1 acid, 1 ketone, 1 pyrazine and 2 alkanes as demonstrated by PCA (principal component analysis) analysis of their relative contents. More volatile compounds were detected as the post-fermentation proceeded. 1-octen-3-ol, 3-methyl-1-butanol, 2-methyl-butanoic acid, ethyl ester, hexanoic acid, ethyl ester, benzeneacetaldehyde, 3-ethoxy-1-propene, 4-hydroxy-2-butanone, tetramethyl pyrazine, 2-methyl-propanoic acid and ethyl ester were predominant during the entire post-fermentation process, and 3-methyl-1-butanol, 2-methyl-propanoic acid, ethyl ester, hexanoic acid, tetramethyl pyrazine, and 2-methyl-propanoic acid and ethyl ester had major contributions to the formation of flavor in Douchi and their contents increased with prolonged post-fermentation time. PCA analysis suggested that the best flavor was achieved after 15 d of post-fermentation followed by 25 d and 30 d.

Key words: Duchi, solid-phase microextraction (SPME), gas chromatography-mass spectrometry (GC-MS), volatile components, principal component analysis (PCA)