摘要
This study investigated the rehydration of active dried yeast and the impact of temperature and wort density on the strength and stiffness of individual cells using a microelectromechanical system. Dried yeast was rehydrated using a variety of methods, including direct pitching into wort (13.6°P) at 12, 22 and 30°C, as well as propagation using YEPD media (4.2°P). Cell viability was found to broadly correlate with measurement of cell strength and stiffness. Both wort density and temperature affected viability and physical characteristics of the cells after 1 h of rehydration. Yeast cells rehydrated at low temperature and high wort density burst at a lower force (0.26 ± 0.02 μN) than cells rehydrated using high temperature and low density media (0.50 ± 0.10 μN). Cells rehydrated at higher temperatures or using low density media showed no significant difference in strength and stiffness when compared with high viability, actively fermenting yeast. Changes in yeast physiology, owing to stress responses, may contribute to the observed differences in mechanical properties. These findings have application in brewery design, as pumping, centrifugation, storage and associated shear impart mechanical stress upon yeast cells. © 2018 The Institute of Brewing & Distilling
摘要译文
该研究使用微机电系统研究了活性干酵母的再水化以及温度和麦芽汁密度对单个细胞的强度和刚度的影响。使用多种方法将干酵母再水化，包括在12,22和30℃下直接投入麦芽汁（13.6°P），以及使用YEPD培养基（4.2°P）进行繁殖。发现细胞活力与细胞强度和刚度的测量广泛相关。在再水合1小时后，麦芽汁密度和温度都影响细胞的活力和物理特性。与使用高温和低密度培养基（0.50±0.10μN）再水化的细胞相比，在低温和高麦芽汁密度下再水化的酵母细胞以更低的力（0.26±0.02μN）破裂。与高活力，主动发酵酵母相比，在较高温度下再水化或使用低密度培养基的细胞在强度和硬度方面没有显示出显着差异。由于应激反应，酵母生理学的变化可能有助于观察到的机械性质的差异。这些发现在啤酒厂设计中有应用，因为泵送，离心，储存和相关剪切赋予酵母细胞机械应力。 ©2018酿造和蒸馏研究所
Bruno Barazani[1];Marta Piercey[2];Allan Paulson[2];Stephan Warnat[3];Ted Hubbard[1];Andrew J. MacIntosh[4]. Rehydration of active dried yeast: impact on strength and stiffness of yeast cells measured using microelectromechanical systems[J]. Journal of the Institute of Brewing, 2019,125(1): 53-59