Comparison of methods for the recovery and detection of low levels of injured Salmonella in ice cream and milk powder

Abstract

This study compared the ability of four rapid methods and a standard cultural method to detect low levels of heat-injured cells of Salmonella typhimurium in ice cream and skimmed milk powder. The detection of Salmonella in samples contaminated with low levels (< 10 cfu 25 g-1) was significantly greater with the novel broth method than with the other methods (P </= 0.01). At contamination levels > 10 cfu 25 g-1, there was no significant difference between the methods except for the novel broth method and a dipstick-based immunoassay (P </= 0.05). The novel broth method, S.P.R.I.N.T. Salmonella, which incorporates a specifically formulated peptone and Oxyrase(R) combination followed by the timed release of selective agents into the recovery medium, was shown to improve the rate of detection of low numbers of injured cells of Salmonella after 24 h enrichment.