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°C min−1. 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 (μ = 0.088 h−1 compared with 0.117 h−1) also showed greater trehalose synthesis and improved frozen-dough stability. Insufficient aeration (dissolved-oxygen deficit) and lower growth temperature (20°C instead of 30°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.
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机译：在实验室规模上评估了先前在各种工业条件下生长的冷冻面团和面包酵母（Saccharomyces cerevisiae）的水悬浮液中的耐低温性。补料分批培养优于分批培养，并且两种情况下的强曝气均可提高冷冻电阻，冷冻速率为1至56°C min -1 。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。强需氧分批培养物以降低的平均比速率生长（μ= 0.088 h -1 与0.117 h -1 相比）也显示出更多的海藻糖合成和改良的冷冻-面团稳定性。充气不足（溶解氧不足）和较低的生长温度（从20°C而不是30°C）降低了补料分批生长的酵母的抗冻性和海藻糖含量。尽管海藻糖在酿酒酵母中具有冷冻保护作用，但即使在补料分批生长培养基中暂时缺乏过量的溶解氧，其作用也被中和。
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