Optimization of Fermentation Process for the Production of Bacteriocins from Lactic Acid Bacteria

[Objective]This study aimed to improve the yield of bacteriocins from lactic acid bacteria by optimizing the fermentation process for production of bacteriocins from lactic acid bacteria.[Method]By single-factor analysis,fermentation temperature,seed age,inoculation volume,fermentation duration and fermentation media p H were optimized to determine the best fermentation process.The inhibitory zone of bacteriocins from lactic acid bacteria was analyzed with oxford cup method,based on which the fermentation process was evaluated.[Result]The optimal fermentation process was optimized：fermentation temperature 37℃,seed age 14 h,inoculation volume 2%,fermentation duration 48 h,fermentation media p H 5.0.[Conclusion]Under the optimized fermentation conditions,the yield of bacteriocins from lactic acid bacteria was improved significantly.

Study on inoculation fermentation by fungi to improve the taste quality of summer green tea

Summer green tea(SGT)is not favored by consumers due to its strong bitterness and astringency.This study aims to improve the taste of SGT using tea-derived fungi isolated from Liupao tea by solid-state fermentation.Based on 19 detected main compounds,principal component analysis(PCA)and hierarchical cluster analysis(HCA)showed Aspergillus sydowii,Penicillium manginii,Aspergillus intermedius,Aspergillus amstelodami,and Aspergillus niger groups were clustered together with significant differences from the control.Additionally,metabolomics analysis showed P.manginii,A.intermedius,and A.amstelodami strains could reduce the chemical components associated with bitter and astringent flavors,such as epicatechin gallate,epicatechin,(+)-gallocatechin,quercetin,kaempferol,myricetin,procyanidin B2,L-phenylalanine and its glycoside derivatives(VIP>1,P<0.05),and increase the contents of theabrownins associated with umami taste(P<0.05).In summary,the taste of SGT can be improved by the above fungi fermentation.