Comparative Analysis of Alkaline Phosphatase Activity and Aerobic Spore-Forming Bacteria in Pasteurized Milk

Abstract

The remaining amounts of alkaline phosphatase (ALP) enzyme in pasteurized milk should be within certain limits. High ALP enzyme level may indicate that the milk has not been pasteurized sufficiently or may be due to excessive growth of spore-forming bacteria in the milk. For this purpose, pasteurized milk samples (n=50) taken from local markets of Manisa were screened for ALP activity and spore-forming bacteria. The ALP activity of most pasteurized milk was below the 350 mU/L limit and ranged from 0 to 500 mU/L. ALP activity was found to be high in only 4% of the 50 milk samples analyzed. The presence of spore-forming bacteria was investigated in suspicious and high ALP activity samples and representative colonies of bacteria that were selected and identified based on biochemical tests. All of the isolates were Bacillus spp. and Bacillus cereus was detected in only one sample. As a result, a positive correlation between ALP activity and the existence of Bacillus spp. was observed for pasteurized milk.

Keywords

• Alkaline phosphatase
• Bacillus sp.
• colourimetric method
• quality control
• pasteurized milk
• spore-forming bacteria

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