酸浆豆腐直投式发酵剂制备和储存条件优化

Optimization of preparation and storage conditions of direct-throwing starter for physalis tofu

目的优化酸浆豆腐直投式发酵剂的制备和储存条件。方法先以菌泥的离心收集率为指标,确定HCUL 1.1901-1912、乳酸链球菌乳亚种1.2472和嗜热链球菌1.2718的离心条件。再以冻干菌粉的存活率为指标,确定离心后菌泥的应激处理条件、冻干pH和菌粉的储存条件。最后检测直投式发酵剂的发酵性能和用其制备的酸浆豆腐品质。结果确定HCUL1.1901-1912、乳酸链球菌乳亚种1.2472和嗜热链球菌1.2718的离心时间为10 min;离心转速分别为6000、8000和6000 r/min;离心初始pH为4.5。菌泥冻干前的应激处理条件为20℃下放置90min;冻干pH为5.5;菌粉的最优储存条件为-20℃冷冻储存。此菌粉在最优储存条件-20℃下冷冻储存9周后,仍能维持76.3%的存活率。将用菌粉与新鲜菌液制作的酸浆豆腐进行质构对比,发现菌粉具有较好的稳定性,且利用储存60d菌粉制备的豆腐与原酸浆豆腐的质构数据比较相似,说明-20℃冷冻储存的菌粉可以很好地代替菌液制作酸浆豆腐。结论此研究为建立科学标准化的酸浆豆腐生产工艺提出了有效解决方案。

Objective To optimize the preparation and storage conditions of direct-throwing starter for physalis tofu.Methods Centrifugal conditions for HCUL 1.1901-1912,Lactococcus lactis subsp.1.2472 and Streptococcus thermophilus 1.2718 were first determined using the centrifugal yield of bacterial mud as an indicator.The survival rate of the lyophilized powder was then used as an indicator to determine the stress treatment conditions,lyophilization pH of the bacterial mud and the storage conditions of the bacterial powder.Finally,the fermentation performance of the direct-throwing starter and the quality of the physalis tofu prepared with it were tested.Results The centrifugation times of HCUL 1.1901-1912,Lactococcus lactis subsp.1.2472 and Streptococcus thermophilus 1.2718 was 10 min;the centrifugal speeds were 6000,8000 and 6000 r/min respectively;centrifugal initial pH was 4.5.Stress treatment conditions before lyophilization of the bacterial mud were placed at 20℃for 90 min;the lyophilization pH was 5.5;the optimal storage condition for bacterial powder was frozen storage at-20℃.This bacterial powder could still maintain a survival rate of 76.3%after being frozen at-20℃for 9 weeks under the optimal storage conditions.Comparing the texture of physalis tofu made with bacterial powder and fresh bacterial liquid,it was found that the bacterial powder had good stability,and there was similar between the texture data of the tofu prepared by storing the bacterial powder for 60 days and the original physalis tofu,which meaned that-20℃frozen storage of the bacterial powder could be a good substitute for the bacterial liquid in making physalis tofu.Conclusion This study puts forward an effective solution for establishing a scientific and standardized production process of physalis tofu.