不同制曲工艺对速成永川豆豉后发酵过程和产品品质的影响

Effect of different koji-making processes on the post-fermentation process and product quality of rapid Yongchuan Douchi

摘要:

【目的】传统永川豆豉和速成永川豆豉生产工艺不同，在风味品质上有着显著的差异。【方法】为明确制曲工艺对豆豉品质的影响，本研究比较了传统自然制曲和米曲霉(Aspergillus oryzae)制曲永川豆豉在速成工艺下的理化特性及微生物群落差异。【结果】自然制曲速成永川豆豉氨基酸态氮含量和色泽显著高于米曲霉制曲速成永川豆豉(P<0.05)，但还原糖含量显著低于米曲霉制曲速成永川豆豉(P<0.05)，2种制曲速成永川豆豉可滴定酸度含量无显著性差异(P>0.05)。微生物分析表明，自然制曲速成永川豆豉微生物丰富度及多样性显著高于米曲霉制曲速成永川豆豉(P<0.05)。自然制曲速成永川豆豉的优势菌属为毛霉菌属(Mucor)、芽孢杆菌属(Bacillus)、肠杆菌属(Enterobacter)、肠球菌属(Enterococcus)、假单胞菌属(Pseudomonas)、葡萄球菌属(Staphylococcus)、维克霉属(Wickerhamomyces)和青霉属(Penicillium)等。米曲霉制曲速成永川豆豉的优势菌属为芽孢杆菌属、棒状杆菌属(Corynebacterium)、曲霉属(Aspergillus)和念珠菌属(Candida)等。此外，2种制曲速成永川豆豉均有少量的德巴利氏酵母属(Debaryomyces)参与。【结论】不同制曲工艺对速成永川豆豉的理化特性和微生物群结构有显著影响，自然制曲速成永川豆豉的关键理化指标显著优于米曲霉制曲速成永川豆豉。

Abstract:

[Objective] Due to the difference in production process, conventional Yongchuan Douchi (fermented soybean product) and rapid Yongchuan Douchi are remarkably different in flavor quality. We explored the effect of koji-making process on the quality of Douchi. [Methods] Yongchuan Douchi was prepared with the rapid process but different koji-making methods (conventional natural process and artificial inoculation of Aspergillus oryzae, respectively). Then we compared the physicochemical properties and microbial community of the products. [Results] The Douchi prepared with the natural koji-making process had higher content of amino acid nitrogen and darker color (P<0.05), lower content of reducing sugar (P<0.05), and higher microbial richness and diversity (P<0.05) than the product prepared with the artificial inoculation of A. oryzae. The two products showed no significant difference in the titratable acid content (P>0.05). The dominant bacterial genera of the Douchi prepared with the natural koji-making process were Mucor, Bacillus, Enterobacter, Enterococcus, Pseudomonas, Staphylococcus, Wickerhamomyces, Penicillium, and those of the Douchi prepared with the artificial inoculation of A. oryzae were Bacillus, Corynebacterium, Aspergillus, and Candida. In addition, a small number of Debaryomyces sp. was found on both of the two products. [Conclusion] The koji-making process had significant influence on the physicochemical properties and microbial community structure of rapid Yongchuan Douchi. The key physicochemical indexes of Douchi prepared with the natural koji-making process were significantly better than those of the Douchi prepared with artificial inoculation of A. oryzae.