Enumeration of Salmonella from poultry carcass rinses via direct plating methods*

Abstract

To evaluate direct plating methods for the estimation of Salmonella load in poultry carcass rinses. Two direct plating tools, the spiral plate count method (SPCM) and the hydrophobic grid membrane filtration (HGMF) method, were adapted to support quantification of Salmonella during poultry processing. Test samples consisted of 180 broiler carcasses from a commercial abattoir, 60 from each of three points in the processing line [pre-inside-outside bird wash (pre-IOBW), prechill and postchill]. The SPCM was used to estimate Salmonella load in pre-IOBW rinses, while HGMF was used to estimate Salmonella levels in prechill and postchill rinses. Carcass rinses were also evaluated for Salmonella prevalence by enrichment methods. Mean prevalences of Salmonella were 95%, 100% and 41.7%, and the geometric mean loads were 3.7 x 10(1), 5.6 x 10(0) and 5.0 x 10(-2) CFU ml(-1) for pre-IOBW, prechill and postchill rinses, respectively. The methods described are useful for estimating the concentration of viable and typical Salmonella in poultry carcass rinses. Direct plating enumeration methods can facilitate the monitoring of Salmonella load on poultry carcasses throughout the production process, and the evaluation of new processing intervention strategies.