不同菌株及制曲方式对豆瓣酱制曲效果的影响

Effects of Aspergillus oryzae Strains and Koji-making Methods on Broad Bean Koji Fermentation

摘要:

为探究发酵菌株和制曲方式对豆瓣曲制曲过程及效果的影响，分别将PNM003和沪酿3.042米曲霉应用于圆盘制曲和传统开放制曲，并考察了几种豆瓣曲制曲过程物料温度、微生物数量、酶活性能、理化指标、游离氨基酸和挥发性成分等差异。结果表明，圆盘制曲过程具有更稳定的物料温度（30.8~34.4 ℃），霉菌数量较开放制曲提高11.52%~26.27%，蛋白酶活力提升16.40~406.79 U•g-1，淀粉酶活力达1 500.06~2 062.38 U•g-1，表现出更优的酶活性能。其中，菌株PNM003制备豆瓣曲霉菌总数及酶活性能最为突出。此外，采用PNM003米曲霉制备的豆瓣曲在圆盘制曲条件下总酸含量（1.00 g/100 g）显著低于开放制曲，且具备更优质的外观品质。同时，其游离氨基酸滋味特征谱也得到了有效改善。挥发性成分分析显示，PNM003菌株产生的风味物质种类较沪酿3.042更丰富，圆盘制曲较开放制曲风味物质多样性更高，且霉味物质百分含量降低至0.38%~2.97%。由此可见，相较于开放制曲，圆盘制曲能显著提升豆瓣曲质量，尤其是以PNM003米曲霉为发酵菌种优势更加明显。该研究为优化豆瓣酱生产工艺、提升豆瓣酱品质提供理论依据。

Abstract:

To investigate the effects of fermentation strains and koji-making methods on broad bean koji production, Aspergillus oryzae strains PNM003 and HUNIANG 3.042 were applied in disc koji-making and traditional open koji-making systems. Changes in substrate temperature, microbial populations, enzymatic activities, physicochemical properties, free amino acid composition, and volatile flavor compounds were systematically analyzed during the koji-making process. The results demonstrated that disc koji-making maintained more stable substrate temperatures (30.8~34.4 ℃), increased mold counts by 11.52%~26.27%, and significantly enhanced protease (16.40~406.79 U•g-1) and amylase activities (1 500.06~2 062.38 U•g-1) compared with open koji-making, indicating superior enzymatic performance. Amongn the tested strains, PNM003-fermented broad bean koji exhibited the highest microbial abundance and enzymatic activities. Moreover, the broad bean koji prepared with A. oryzae PNM003 under disc koji-making conditions showed significantly lower total acidity (1.00 g/100 g) than that produced by open koji-making, along with improved visual appearance and a more favorable free amino acid taste profile. Volatile compound analysis revealed that PNM003 generated a richer and more diverse aroma profile than HUNIANG 3.042. Disc-koji-making further increased flavor diversity and reduced the proportion of musty compounds to 0.38%~2.97%. These findings indicate that disc koji-making significantly enhances the quality of broad bean koji, particularly when using the A. oryzae PNM003 strain, providing a scientific basis for optimizing Doubanjiang (broad bean paste) fermentation processes and improving product quality.