探究嗜热链球菌和乳酸乳球菌蔗糖利用能力的差异性对豆乳发酵菌株筛选的影响,并对菌株发酵豆乳样品的挥发性风味物质进行了分析。通过对12株实验菌株的蔗糖利用能力进行评价,测定菌株在以蔗糖为单一碳源环境下的生长、产酸情况,挑选菌株进行豆乳发酵特性评价,并运用GC-MS对发酵样品进行挥发性风味物质分析,了解不同菌株的蔗糖利用的差异及对豆乳发酵的影响。结果表明,不同实验菌株蔗糖利用能力具有显著差异,乳酸乳球菌实验菌株蔗糖利用能力显著优于嗜热链球菌;乳酸乳球菌DYNDL21-2可在豆乳发酵6 h后达到发酵终点,并代谢掉豆乳体系中65.38%的蔗糖(达1.766 g/L);发酵豆乳终点样品中己醛含量显著降低,有的菌株最高可生成198.49 μg/L奶香味物质2,3-丁二酮,及492.19 μg/L果香味物质3-甲基丁醇。菌株DYNDL21-2、HeNa-28-3-GMM和15G5的蔗糖利用能力良好,可快速发酵大豆豆乳,并使发酵豆乳风味得到显著改善,具有良好应用潜力。
The effects of sucrose utilization capacity on the screening of soymilk fermented strains in Streptococcus thermophilus and Lactococcus lactis were investigated, and the volatile profile of the fermented soymilk samples was analyzed. To analyze the sugar utilization ability of 12 strains, the growth and acid production of the selected strains were determined in sucrose-MRS broth where sucrose was the sole carbon source. The characteristics of the fermented soymilk samples were evaluated and volatile flavor substances were analyzed by GC-MS to understand the differences of sucrose utilization between strains and the effects on soymilk fermentation. The results showed that the sucrose utilization capacity of different experimental strains was significantly different, and the selected L. lactis strains generally showed higher sucrose utilization ability than the selected S. thermophilus strains. DYNDL21-2, a strain with good sucrose utilization ability, could ferment the soymilk and reach a pH below 4.7 within 6 h, and metabolized 65.38% sucrose (up to 1.766 g/L) in soymilk. Moreover, the content of hexanal in fermented soymilk samples was significantly reduced, with high concentrations of 2,3-butanedione (198.49 μg/L) and 3-methyl-butanol (492.19 μg/L) which contributed to creamy and fruity sensations. In summary, 3 strains with good sucrose utilization ability, DYNDL21-2, HeNa-28-3-GMM and 15G5, could rapidly ferment soymilk and significantly improved the volatile profile of the fermented soymilk.
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