ENUMERATION OF MEATBORNE SPOILAGE BACTERIA WITH HYDROPHOBIC GRID MEMBRANE FILTRATION

Hydrophobic grid membrane filtration (HGMF) was investigated as an alt ernative to conventional plate counts for enumerating spoilage bacteri a recovered from raw beef. The HGMF method was compared to conventiona l procedures for the selective enumeration of total psychrotrophic bac teria, pseudomonads, total Enterobacteriaceae, Brochothrix thermosphac ta, and lactic acid bacteria, Bacteria were recovered both from beef w hich had been artificially inoculated with identified strains and from naturally contaminated beef from a commercial abattoir. There were no significant differences (P > 0.05) in numbers of any bacterial group recovered from naturally contaminated beef using HGMF procedures when compared to conventional plating on selective media. The recoveries of the total psychrotrophic population, Escherichia coli, B. thermosphac ta and Lactobacillus sake inoculated onto meat were unaffected by the enumeration procedure (P > 0.05). However, the populations of Pseudomo nas sp. recovered from inoculated beef by a HGMF procedure were 0.8 lo g cycles lower (P < 0.05) when compared to the conventional spread pla te procedure.