[目的]生乳发酵试验,达到发酵终点时间长,需要等到发酵完成才能发现异常,使用溴甲酚紫法发酵能在发酵过程中通过颜色的改变提前直观的发现发酵过程异常。[方法]在煮沸冷却后的生乳中,加入4~5 mL母菌种和1.0 mL 0.1 g/L的溴甲酚紫指示剂,在温度为（45±1） ℃的水浴锅中温育。[结果]温育2 h,样液的颜色随着发酵作用从蓝色变为黄色,即为正常发酵。[结论]此法能在发酵2 h时观察到发酵颜色变化。对比目前普遍使用的发酵方法可提前观察发酵情况,更早对异常情况进行分析处理,在实际应用中可以辅助使用。

[Objective]The raw milk fermentation experiment takes a long time to reach the fermentation end point,and the abnormality can be found only after the fermentation is completed. The bromocresol purple fermentation method can intuitively find the abnormality of the fermentation process in advance through the change of color during the fermentation process.[Method]Add 4~5 mL of mother strain and 1 mL of 0.1 g/L bromocresol violet indicator to the boiled and cooled raw milk,and incubate in a water bath at（45±1） ℃.[Result]After incubation for 2 hours,the color of the sample solution changes from blue to yellow with the fermentation, which is normal fermentation. [Conclusion]This method can observe the change of fermentation color after fermentation for 2 hours. Compared with the commonly used fermentation methods, the fermentation situation can be observed in advance and the abnormal situation can be analyzed and handled earlier, which can be used as an auxiliary in practical application.