RESUMO
Bacterial counts were done at 7°C for 10 d and at 18°C for 45 h on 93 samples of raw and 185 samples of pasteurized milk. As an additional test, catalase-positive microorganisms were enumerated at 18°C/45 h. Close correlations were obtained between the numbers of microorganisms following 18°C/45-h and 7°C/10-d incubations in raw (r2=0.866) and pasteurized (r2=0.936) milk samples. Similar correlations (r2=0.860 and 0.946) were noted for the 18°C/45-h-catalase and the 7°C/10-d methods for raw and pasteurized milk, respectively. Results suggest that incubation at 18°C for 45 h provides a reliable estimate of the numbers of psychrotrophs in raw and pasteurized milk and that the use of catalase does not improve sensitivity of the test significantly.
