Lallemand Inc., Montreal, Quebec H1W 2N8, Canada, and Département de Sciences et Technologie des Aliments and Département de Génie Chimique, Université Laval, Sainte-Foy, Quebec G1K 7P4, Canada.
Appl Environ Microbiol. 1989 Oct;55(10):2453-9. doi: 10.1128/aem.55.10.2453-2459.1989.
The cryotolerance in frozen doughs and in water suspensions of bakers' yeast (Saccharomyces cerevisiae) previously grown under various industrial conditions was evaluated on a laboratory scale. Fed-batch cultures were very superior to batch cultures, and strong aeration enhanced cryoresistance in both cases for freezing rates of 1 to 56 degrees C min. Loss of cell viability in frozen dough or water was related to the duration of the dissolved-oxygen deficit during fed-batch growth. Strongly aerobic fed-batch cultures grown at a reduced average specific rate (mu = 0.088 h compared with 0.117 h) also showed greater trehalose synthesis and improved frozen-dough stability. Insufficient aeration (dissolved-oxygen deficit) and lower growth temperature (20 degrees C instead of 30 degrees C) decreased both fed-batch-grown yeast cryoresistance and trehalose content. Although trehalose had a cryoprotective effect in S. cerevisiae, its effect was neutralized by even a momentary lack of excess dissolved oxygen in the fed-batch growth medium.
实验室规模评估了在不同工业条件下生长的冷冻面团和面包酵母（酿酒酵母）水悬浮液的耐冷性。与批次培养相比，补料分批培养非常优越，并且在两种情况下，强烈的通气都会增强抗冷冻能力，冷冻速率为 1 至 56°C/min。冷冻面团或水中细胞活力的丧失与补料分批生长过程中溶解氧缺乏的持续时间有关。在较低平均比生长速率（μ=0.088 h 而不是 0.117 h）下生长的需氧强烈的补料分批培养也显示出更高的海藻糖合成和改善的冷冻面团稳定性。通气不足（溶解氧缺乏）和较低的生长温度（20°C 而不是 30°C）降低了补料分批培养的酵母耐冷性和海藻糖含量。尽管海藻糖对酿酒酵母具有保护作用，但即使在补料分批生长培养基中瞬间缺乏过量溶解氧，其作用也会被中和。
