Recovery of Salmonella from High-Moisture Foods by Abbreviated Selective Enrichment

Abstract

Five high-moisture foods were used to evaluate both the effect of a 6 h, rather than the standard 24 h, selective enrichment incubation period, and the efficiency of Rappaport-Vassiliadis (RV) medium relative to the use of selenite cystine (SC) and tetrathionate (TT) broths for the recovery of Salmonella. Cheese and lettuce were artificially inoculated with a pool of two serotypes, whereas the other foods were naturally contaminated. Significantly higher numbers of Salmonella-positive test portions were obtained at 24 h with the following food and media combinations: cheese (TT and RV media), lettuce (SC, TT, and RV media), raw chicken (RV medium), and pork sausage (SC, TT, and RV media). There were no significant differences between the two incubation periods in recovery of Salmonella from turkey. Overall, more Salmonella-positive test portions were obtained from samples of lettuce, chicken, and pork sausage selectively enriched in RV medium than in SC or TT broths. The results of this study indicate that not all high-moisture foods can be selectively enriched for 6 h without a significant loss in recovery of Salmonella. RV medium was superior to SC and TT broths for recovery of Salmonella from some meats and was at least as productive in its recovery from the other high-moisture foods tested.