The optimal pH value was adjusted to 9.4 by adding 0.1 M Lactic acid. Each sample was prepared by mixing 0.1 ml of microbial culture with 0.9 ml of aseptic milk, which was blended with Fraser broth at a ratio of 1:0.7 in the reaction cell. Thereafter the electrochemical detection system was performed at 37 °C, 1 V and the resulting current response was employed to calculate the growth of the microbes.