Conway J, Gaudreau H, Champagne C P
Lallemand Inc., 1620 Préfontaine, Montréal, QC H1W 2N8, Canada.
Can J Microbiol. 2001 Jan;47(1):18-24. doi: 10.1139/w00-118.
Yeast extracts (YE) were produced with the addition of proteases or glucanases during bakers' yeast (Saccharomyces cerevisiae) autolysis. Chemical composition, physical properties, and biological value of the YE were examined. Proteases had the highest impact on the turbidity and filterability of YE. All 11 proteases and two glucanases increased YE yields (% yeast solids solubilized) obtained from heated (80 degrees C/15 min) bakers' yeast creams (BYC). However, when proteases were added to native (unheated) BYC during autolysis, few increased YE yields, with papain being the most effective. The increased yields were generally related to increased levels of total nitrogen (TN) and alpha-amino nitrogen (alpha-AN) in the YE. Media were supplemented with the various yeast extracts, and the highest growth rates (mumax) and biomass values (ODmax) of Lactobacillus acidophilus were noted. The best growth was obtained with YE produced with native BYC treated with a fungal protease, and results of this study show that some enzymes could be used to produce improved YE for microbiological media.
在面包酵母（酿酒酵母）自溶过程中添加蛋白酶或葡聚糖酶来生产酵母提取物（YE）。对YE的化学成分、物理性质和生物学价值进行了检测。蛋白酶对YE的浊度和过滤性影响最大。所有11种蛋白酶和两种葡聚糖酶均提高了从加热（80℃/15分钟）的面包酵母膏（BYC）中获得的YE产量（溶解的酵母固形物百分比）。然而，在自溶过程中向天然（未加热）的BYC中添加蛋白酶时，很少能提高YE产量，木瓜蛋白酶最为有效。产量的增加通常与YE中总氮（TN）和α-氨基氮（α-AN）水平的提高有关。用各种酵母提取物补充培养基，观察到嗜酸乳杆菌的最高生长速率（μm ax）和生物量值（OD max）。用经真菌蛋白酶处理的天然BYC生产的YE获得了最佳生长效果，本研究结果表明，一些酶可用于生产改良的用于微生物培养基的YE。
