不同温度低盐酱油发酵过程中微生物及品质的变化

Changes in Microorganisms and Quality of Low Salt Soy Sauce during Fermentation at Different Temperatures

摘要:

为了探究不同发酵温度对低盐酱油发酵过程中微生物及其产品品质的影响，该文分别在45、35、25 ℃及自然条件下发酵低盐酱油，并对发酵过程中微生物数量、理化指标及成熟酱醪的品质指标进行了分析。结果表明，发酵温度对低盐酱油发酵存在不同程度的影响。其中，45 ℃高温发酵过程中酵母菌快速消亡；而其它温度整个发酵过程中酵母菌数量始终处于较高数量水平（6.00 lg CFU/g），因而也导致不同温度发酵过程中微生物总数的显著差异。相对而言，45 ℃高温发酵有利于提升发酵速度，其还原糖含量（2.52 g/100g）、甜味氨基酸含量（11.92 g/kg）要明显高于其它温度，且生物胺含量（78.88 mg/kg）更低。但45 ℃发酵不利于低盐酱油中挥发性风味化合物的形成和积累，尤其是酚类和酯类化合物；而发酵温度越低越有利于酚类、酯类化合物等的积累。感官评价结果表明，35 ℃发酵酱油感官品质最好，其次是45 ℃发酵酱油，而25 ℃和自然条件发酵酱油色泽和香气均较差。此外，中低温（35、25 ℃和常温）条件下，在发酵末期酱醪表面“产膜”严重。综上所述，45 ℃能保证低盐酱油正常稀态发酵，但其风味及色泽还存在不足。该研究结果可为今后低盐酱油发酵工艺优化与调控提供参考。

Abstract:

To investigate the effects of different fermentation temperatures on the microorganisms and product quality of low-salt soy sauce fermentation process, this study fermented low salt soy sauce at 45, 35, 25 ℃, and natural conditions, and analyzed the microbial quantity, physicochemical indicators, and quality indicators of mature sauce mash during the fermentation process. The results indicated that different temperatures had varying degrees of impact on the fermentation of low salt soy sauce. Among them, yeast rapidly dies out during the high-temperature fermentation process at 45 ℃; However, the yeast count remained at a relatively high level (6.00 lg CFU/g) throughout the entire fermentation process at other temperatures, resulting in significant differences in the total number of microorganisms during fermentation at different temperatures. Relatively speaking, high-temperature fermentation at 45 ℃ was beneficial for improving fermentation speed, with significantly higher levels of reducing sugars（2.52 g/100g）and sweet amino acids（11.92 g/kg）compared to other temperatures, and lower levels of biogenic amines（78.88 mg/kg）. However, fermentation at 45 ℃ was not conducive to the formation and accumulation of volatile flavor compounds in low salt soy sauce, especially phenolic and ester compounds; The lower the fermentation temperature, the more favorable it was for the accumulation of phenols, esters, and other compounds. The sensory evaluation results showed that the sensory quality of soy sauce fermented at 35 °C was the best, followed by soy sauce fermented at 45 °C. The color and aroma of soy sauce fermented at 25 °C and under natural conditions were both poor. Additionally, at medium to low temperatures (35, 25 ℃, and room temperature), a serious "film production" occurs on the surface of the fermented liquor at the end of fermentation. In summary, 45 °C can ensure the normal dilute state fermentation of low-salt soy sauce, but its flavor and color still have some shortcomings. The results can provide reference for the optimization and regulation of low-salt soy sauce fermentation process in the future.