School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China.
Tianjin Research Institute of Industrial Microbiology Co., Ltd., Tianjin 300462, China.
J Dairy Sci. 2022 Feb;105(2):1072-1083. doi: 10.3168/jds.2021-20997. Epub 2022 Jan 5.
Exopolysaccharide from Leuconostoc pseudomesenteroides XG5 (XG5 EPS) is a linear dextran that is built by glucose units via α-1,6 glycosidic bond. The primary objective of this study was to investigate the yield of XG5 EPS and its application in set yogurt. In laboratory scale, the culture conditions of XG5 EPS production were optimized using the L9 (3) orthogonal test. Here, the optimized yield of XG5 EPS was 26.02 g/L under the conditions of 100 g/L sucrose, initial pH 7.0, 25°C incubation, and 100 rpm for 36 h in a shaking flask. Based on the optimized parameters of laboratory scale, a pilot fed-batch fermentation was performed in a 50-L bioreactor with an adjusted agitation speed of 20 rpm. The XG5 EPS yield reached 40.07 g/L in fed-batch fermentation, which was 54% higher than that achieved in laboratory scale. In addition, XG5 EPS was added into set yogurt to investigate its effect on the stability of set yogurt. Our data demonstrated that the XG5 EPS improved the water-holding capacity, texture profile, and viscosity of set yogurt during cold storage compared with the controls. In particular, addition of 0.5% XG5 EPS increased the structure of 3-dimensional network of set yogurt, which eventually improved the physical stability of the set yogurt. Overall, this study provided new insights for exploring the pilot scale production and application of dextran.
肠膜明串珠菌 XG5（XG5 EPS）的胞外多糖是一种通过α-1,6 糖苷键连接葡萄糖单元构建的线性葡聚糖。本研究的主要目的是研究 XG5 EPS 的产量及其在凝固型酸奶中的应用。在实验室规模下，采用 L9（3）正交试验优化了 XG5 EPS 生产的培养条件。在此条件下，XG5 EPS 的最佳产量为 26.02 g/L，条件为 100 g/L 蔗糖、初始 pH 值 7.0、25°C 孵育和摇瓶中 100 rpm 搅拌 36 h。基于实验室规模的优化参数，在 50-L 生物反应器中进行了分批补料发酵，搅拌速度调整为 20 rpm。在分批补料发酵中，XG5 EPS 的产量达到 40.07 g/L，比实验室规模提高了 54%。此外，将 XG5 EPS 添加到凝固型酸奶中，研究其对凝固型酸奶稳定性的影响。我们的数据表明，与对照相比，XG5 EPS 提高了冷藏过程中凝固型酸奶的持水力、质构特性和黏度。特别是添加 0.5% XG5 EPS 增加了凝固型酸奶三维网络结构的形成，从而最终提高了凝固型酸奶的物理稳定性。总体而言，本研究为探索葡聚糖的中试规模生产和应用提供了新的见解。
