Performance of two ready-to-use systems for enumeration of aerobic mesophilic microorganisms in frozen goat milk

Abstract

Enumeration of aerobic microorganisms in Brazilian pasteurized bovine milk using PetrifilmTM AC and SimplateTM TPC was shown to be influenced by the nature of autochthonous microbiota. This study was conducted to assess if the same occurs in pasteurized goat milk. Pasteurized frozen goat milk (n=62) was purchased in retail stores in Sao Paulo, SP, Brazil, and submitted to mesophilic aerobic counts using PetrifilmTM AC and SimplateTM TPC, comparing results with those of conventional pour-plates. Correlation indexes above 0.90 were ranked excellent; those between 0.80 and 0.89, good, those from 0.79 to 0.50, fair, and those below 0.50, poor. Correlation indexes for PetrifilmTM AC counts were good, but poor using SimplateTM TPC. Comparison of PetrifilmTM AC and SimplateTM TPC also produced poor correlation indexes. Results suggest that autochthonous microbiota have little, if any, influence on the performance of these two systems, since good correlations were achieved using PetrifilmTM AC.