We evaluated the effects of fermentation time and acid casein content on the microbial rennet obtained by solid-state fermentation using wheat bran as the carbon source. The experiments used two fermentation times (72 and 96 h), while acid casein content was 1.5, 2.0, 2.5, and 3.0 g. Rennet strength from eight enzymatic extracts was measured using pasteurized whole milk. Rennet strength of samples from 72 h of fermentation showed an increase when acid casein content increased. The rennet strength increased at 96 h of fermentation with increasing amount of casein (up to 2.5 g), and then decreased with the largest addition (3.0 g) of casein. Coagulation time for the sample with highest rennet strength was 420 s.

中文翻译：

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发酵时间和酸性酪蛋白浓度作为氮源对微生物凝乳酶产量的影响

我们评估了发酵时间和酸性酪蛋白含量对以麦麸为碳源的固态发酵获得的微生物凝乳酶的影响。实验使用两个发酵时间（72 和 96 小时），而酸性酪蛋白含量为 1.5、2.0、2.5 和 3.0 g。使用巴氏杀菌全脂牛奶测量来自八种酶提取物的凝乳酶强度。当酸性酪蛋白含量增加时，发酵 72 小时的样品的凝乳酶强度增加。凝乳酶强度在发酵 96 h 时随着酪蛋白量的增加（最高 2.5 g）而增加，然后随着酪蛋白的最大添加量（3.0 g）而降低。具有最高凝乳酶强度的样品的凝固时间为 420 秒。