LI Jinlin, WAN Liang, WANG Weiya, HUANG Li, WANG Xiaolan, TU Zongcai
Douchi is a traditional Chinese fermented soybean product. To investigate the formation of flavor compounds in Jiangxi Aspergillus-type Douchi during fermentation,the volatile components at three stages of Douchi fermentation was analyzed by gas chromatography-mass spectrometry coupled with solid phase micro-extraction (SPME-GC-MS),and the extraction efficacy of fibers DVB/CAR/PDMS,PDMS/DVB,Carboxen/PDMS and PDMS was also compared. Results indicated that the PDMS/DVB fiber was suitable for the volatiles extraction from soybean product. A total of 24 volatile compounds,including 1 furan,5 pyrazines,4 aldehydes,3 alcohols,2 ketones,2 acids,4 phenols,and 3 other compounds,were identified in soybean after koji-making,45 compounds (3 furans,4 pyrazines,7 aldehydes,5 alcohols,2 ketones,4 acids,11 esters,2 sulfides,5 phenols,and 2 other compounds) were detected in the post-fermentation samples. 50 compounds,including 3 furans,6 pyrazines,7 aldehydes,7 alcohols,2 ketones,4 acids,11 esters,2 sulfides,5 phenols,and 3 other compounds,were found in dried Douchi. Therefore,small amounts of volatile compounds were formed after koji-making and more volatile compounds were found during post fermentation,the key stage for flavor compounds formation,with higher content. Dry process could change the content of flavor compounds slightly,but would not change the flavor characteristic of Douchi in whole.
