Survival study and haemolysin activity of Escherichia coli in raw and pasteurized milk produced in Negeri Sembilan / Farra Amira Mohamed, Aimi Nadia Ramli and Noorlis Ahmad

Demand for milk has increased in Malaysia due to the increased in awareness of healthy foods consumption. Hence, research of milk is crucial to ensure that it is not contaminated with Escherichia coli. This study evaluated the survival of Escherichia coli at different temperature and haemolysin activity of Escherichia coli on blood agar. A total of 8 samples of raw fresh and pasteurized milk were collected from nearby farm and market in Negeri Sembilan, Malaysia. After an overnight exposure to four different temperatures of 00C, 280C, 350C and 450C, the bacteriological test of milk was evaluated for the presence of Escherichia coli. Overall, all raw fresh milk sampled exceeded the acceptable limit of bacterial count of 1 x 105 CFU/ml. Raw fresh milk recorded the highest count at 35oC with 4.4 x 107 CFU/ml and the lowest at 0oC with 8.3 x 104 CFU/ml. The presence of Escherichia coli was detected in 7/20 (35%) of the total raw fresh milk samples. All pasteurized milk showed no presence of Escherichia coli due to the effectiveness of heat treatment. Haemolysin test showed no haemolytic activity. Milk contaminated with Escherichia coli can cause diarrheal, gastrointestinal diseases and urinary infection. Hence, it is important to study the survival rate of Escherichia coli and its pathogenicity in milk to ensure public safety.