Evaluation of the Petrifilm™ and TEMPO® systems and the conventional method for counting microorganisms in pasteurized milk

Abstract

New microbiological methods have been developed and commercialized, but their performance must be guaranteed. The aim of the present study was to evaluate the Petrifilm™ and TEMPO® systems compared to the conventional method for counting microorganisms in pasteurized milk. A total of 141 samples of pasteurized milk were analyzed by counting mesophilic aerobic, Coliforms at 35 °C, Coliforms at 45 °C, and Escherichia coli microorganisms. High correlation was found between the methods for counting Coliforms at 35 °C, but low correlation was found for counting mesophilic aerobic, Coliforms at 45 °C, and Escherichia coli. No significant statistical difference was found among the three methods for counting Coliforms at 35 °C; however, the mean counts of mesophilic aerobic, Coliforms at 45 °C, and Escherichia coli showed significant statistical difference. Petrifilm™ and TEMPO® systems had satisfactory results for Coliforms at 35 °C in pasteurized milk but low performance for mesophilic aerobic, Coliforms at 45 °C and Escherichia coli.