Comparison Study of 3Mâ„¢ Petrifilmâ„¢ E. coli / Coliform Count (EC) Plates vs. IS Methods for Enumeration of Coliforms (IS-5401 Part-1) and E. coli (IS 5887: Part-1) to Evaluate Quality of Indian Milk and Milk products

Abstract

The objective of this study was to analyze the quality of milk and milk based products of the local Indian market, for Coliforms & Escherichia coli by conventional pour plate method and Petrifilm EC Plate method and to compare these two methods. A total of 20 fresh retail samples were analyzed for coliform counts to correlate the methods independently. Linear regression of counts determined from Petrifilm EC Plate versus IS methods with VRBA, after log transformed, gave R=0.995, and p≥0.5, which showed that results were statistically non-significant. Simultaneously, another set of comparison was done for Escherichia coli count, by spiking 5 samples with known count of Escherichia coli. The results from both Petrifilm EC Plate & IS methods with EMB agar were compared by student t-test, which showed p ≥0.5, indicating no significant difference between the two methods. Use of Petrifilm EC Plates is convenient and gave comparative results. Petrifilm EC Plate method needed only 1/4^th of the time when compared to that of traditional plating method. Petrifilm EC Plates offer a good alternative for determining total coliform count and especially with target of fecal Escherichia coli in single performed test which are also bio-chemically confirmed. Petrifilm EC Plate is also cost-effective as compared to the conventional method.