Dynamic Analysis Of Post-fermentation Process In Aspergillus-type Douchi Produced By Induced Method

With the rapid development of condiment industry, the more attention and research have been focus on Douchi. At present, there are still some problems in traditional production process of Douchi in our country, such as long production cycle, high salinity and unstable quality. The post-fermentation process of Douchi is less systematic studied. In this paper, we prepared Aspergillus-Type Douchi through induced method with different salinity of 7%, 9%, 11%, 13%. The dynamic changes in total number of bacteria, mould and yeast were discussed. The physical and chemical indexes and antioxidant activity were studied. The comparition between Douchi produced by traditional method and induced method under the salinity of 9%.(1)The total number of bacteria, mould and yeast reduced during the early period of post-fermentation. The maximum number of bacteria and mould were 1.4×105cfu/g,9.8×103cfu/g on the 10 th, respectively. And the maximum number of yeast was 10×105cfu/g on the 15 th. The number of them changed a little after the 20 th. During the post-fermentation process, the number of microorganisms exhibited the diminish trend with the increasing of salinity.(2)Douchi prepared by induced method under the different salinity, the total content of amino nitrogen and total acid increased, the reducing sugar content increased first then decreased, the proteinase activity were decreased with the extension of the post-fermentation period. The total content of amino nitrogen, total acid, reducing sugar, and proteinase activity decreased with the increasing of salinity(13%<11%<9%<7%).(3)Under the different salinity, DPPH radical scavenging activity, hydroxyl radical scavenging activity and Fe3+ reducibility were increased with the extension of post-fermentation period. DPPH radical and hydroxyl radical scavenging activity under the high salinity were weaker than it under the low salinity(13%<11%<9%<7%). But Fe3+reducibility of Douchi was the most weak under 13% salinity, and the strongest under 7%salinity.(4)Under the salinity of 9%, the proteinase activity, total content of amino nitrogen,total acid, reducing sugar and antioxidant activity had the same change trend between the two different fermentation techniques. But the content of amino nitrogen, total acid, reducing sugar in Douchi prepared by traditional method were lower than the ones prepared by induced method. So were the proteinase and antioxidant activity.The results showed that the quality of Douchi prepared by induced method was more prior than the one prepared by traditional method. It laid the foundation for improving traditional fermentation process and enhance the quality of Douchi.