Comparison of Petrifilm method to conventional methods for enumerating aerobic bacteria, coliforms, Escherichia coli and yeasts and molds in foods.

Abstract

The Petrifilm plates method was compared to conventional methods (PCA, VRBA, Levine EMB agar and OGYE agar) for enumeration of mesophilic aerobic bacteria, coliforms, Escherichia coli, and yeasts+molds in six homogeneous lots of different food groups (pasteurized milk, yoghurt ice cream, eggs, minced meat, fresh strawberries and frozen green beans). For all the microbiological criteria except for yeasts and molds and mesophilic aerobic bacteria in frozen green beans, the mean values of counts with Petrifilm plates were higher than those obtained with traditional methods. The correlation coefficient of Petrifilm aerobic bacteria, coliforms, and yeasts + molds v. PCA, VRBA and OGYE agar for each microbiological criterion for a composite of six food products were 0.897, 0.861 and 0.981, respectively.