Purpose: The purpose of the study was to evaluate performance of the ANSR Salmonella method for detection of Salmonella spp. in ice cream, almonds, soy flour, cocoa powder, dried pasteurized egg, peanut butter, black pepper, spinach, raw frozen shrimp, and dry pet food in comparison to that of the reference culture methods of FDA-BAM or USDA-MLG.
Methods: Food samples were inoculated with Salmonella spp. and held under conditions intended to simulate natural contamination with sublethally injured cells. For each food tested, 40 or 50 test portions were inoculated at a level predicted to produce a fractional positive data set, and 10 test portions served as uninoculated controls. Half of the test portions were analyzed by the ANSR method after both 16 and 24 hours of enrichment. The remaining test portions were analyzed by the reference procedure.
Results: A total of 728 test portions were analyzed in the study. There were a total of 152 positive results by the method (24 hours) and 164 by the reference procedures. Results were analyzed using both chi-square and probability of detection statistical methods. For all 10 foods tested, there were no statistically significant differences in the number of positive results obtained by the ANSR method at 24 hours and the reference procedures. Results with the test method at 16 hours were statistically equivalent to those of the reference methods for 8 foods, with only ice cream and dried egg producing significantly more positive results by the reference method.
Significance: Successful completion of this study has resulted in expansion of the AOAC validated claims for the test method to a total of 15 foods and 5 environmental sample types.