Microbiology of ground beef = II. A modified resazurin reduction test for determination of quality

Abstract

Forty samples of ground beef were taken at four supermarkets in the city of Piracicaba, SP. Total bacterial counts were determined using a produre recommended by the American Public Health Association; the plates were incubated at 32°C (48 hours). A modified procedure based on resazurin reduction for the determination of ground beef microbiological quality was studied. The results can be summarized as follows = 1) Total counts were generally higth, with several samples in the range 10(7) to 10(9) cells/gram; the average count was 3,0 x 10(7) cells/gram. 2) The differences between counts related to any two supermarkets were not statistically significant. 3) Resazurin reduction to colorless was significantly correlated with total bacterial counts (r=-0,91).