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 Petrifilm™ AC and Simplate™ 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 São Paulo, SP, Brazil, and submitted to mesophilic aerobic counts using Petrifilm™ AC and Simplate™ 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 Petrifilm™ AC counts were "good", but "poor" using Simplate™ TPC. Comparison of Petrifilm™ AC and Simplate™ 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 Petrifilm™ AC.