State Key Laboratory of Food Science and Technology, The Key Laboratory of Industrial Biotechnology, Ministry of Education, Synergetic Innovation Centre of Food Safety and Nutrition, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China; Bioprocess Engineering, Wageningen University and Research, P.O. Box 16, 6700 AA Wageningen, The Netherlands.
Bioprocess Engineering, Wageningen University and Research, P.O. Box 16, 6700 AA Wageningen, The Netherlands.
Bioresour Technol. 2019 Apr;277:68-76. doi: 10.1016/j.biortech.2019.01.038. Epub 2019 Jan 9.
Water is crucial for microbial growth, heat transfer and substrate hydrolysis, and dynamically changes with time in solid-state fermentation. However, water dynamics in the solid substrate is difficult to define and measure. Here, nuclear magnetic resonance was used to monitor water dynamics during the pure culture of Aspergillus oryzae YH6 on wheat in a model system to mimic solid starter (Qu or Koji) preparation. During fermentation, overall water content gradually decreased from 0.84 to 0.36 g/g, and water activity decreased from 0.99 to 0.93. Water content in different state (bound, immobilized and free) changed differently and all moved to more "bound" direction. The internal water distribution over the substrate matrix also showed a faster reduction inward both in the radical and axial direction. Our findings provide the prerequisites for optimal processes where water dynamics in solid-state fermentation can be monitored and controlled.
水是微生物生长、热传递和基质水解的关键，在固态发酵中随时间动态变化。然而，固态基质中的水动力学很难定义和测量。在这里，我们使用核磁共振来监测模型系统中纯培养米曲霉 YH6 在小麦上发酵时的水动力学，以模拟固态发酵剂（Qu 或 Koji）的制备。在发酵过程中，总含水量逐渐从 0.84 降至 0.36 g/g，水活度从 0.99 降至 0.93。不同状态（结合态、固定态和游离态）的水分含量变化不同，并且都向更“结合”的方向移动。基质内部的水分分布也在径向和轴向都呈现出更快的向内减少。我们的发现为监测和控制固态发酵中水动力学的最佳工艺提供了前提条件。
