Purpose: To determine the minimum enrichment time required to detect Salmonella at inoculation target level of 0.3 to 0.55 CFU/g in post-enrichment, wet pooled samples of ground beef and beef trim with Assurance GDS for Salmonella (GDS) which will ensure the desired limit of detection of 1CFU/g of Salmonella.
Methods: A five-strain cocktail of Salmonella spp. was used for this study. Seventy-four samples of 375 g ground beef were inoculated at 0.55 CFU/g. Seventy-three samples of 75 g beef trim were inoculated at 0.3 CFU/g. Four uninoculated ground beef and four beef trim samples were enriched for wet pool analysis. All ground beef samples were incubated for 5 hours and all beef trim samples were incubated for 4.5 hours. All individual samples were tested individually and as wet pooled samples (1:5).
Results: In summary, a total of 147 inoculated samples were tested. All 147 individual inoculated samples were positive and all uninoculated samples were found negative with GDS. All 147 wet pooled samples, created by combining 4 uninoculated samples with 1 inoculated sample, also were positive by GDS. All individual samples were culturally confirmed.
Significance: This validation study demonstrates that five hours incubation for fresh raw ground beef and 4.5 hours of incubation for fresh raw beef trim, with an average inoculation level of 0.55 and 0.3 CFU/g, respectively, which is less than the Salmonella limit of detection of 1 CFU/g met the USDA sensitivity requirements of 97%.