Effectiveness of selected pre-enrichment broths for the detection of Salmonella spp. in meat analogs

Abstract

With the increasing variety of meat analog products, it is important to verify that the methods used for Salmonella detection are effective. The objective of this study was to compare the efficacy of three pre-enrichment broths for the detection of Salmonella in meat analog burgers: the currently used Bacteriological Analytical Manual (BAM) broth (lactose broth with Triton X-100, LB-T), universal pre-enrichment (UP) broth, and buffered peptone water (BPW). Five different meat analog products (coded A-E) were inoculated with Salmonella serotypes (S. Enteritidis or S. Agona) following the Food and Drug Administration Method Modification and Method Extension Criteria for Existing Validated Microbiology Methods. Seven replicates were tested per product with each broth, for a total of 105 inoculated samples and 105 uninoculated samples. Salmonella was isolated as described in the BAM, and two isolated colonies from each sample were tested with real-time PCR. The total number of positive real-time PCR detections associated with each pre-enrichment broth was compared across all products (70 PCR tests per broth) and within each brand (14 PCR tests per broth). Overall, LB-T showed the greatest detection rate of 65/70 (92.9%), while BPW and UP showed rates of 63/70 (90.0%) and 62/70 (88.6%), respectively. However, these differences were not statistically significant (p-value > 0.05, Test for Equality of Proportions). When the broths were compared separately for each product, LB-T showed a significantly greater detection rate of 13/14 (92.9%) in Brand C samples compared to UP at 7/14 (50.0%). These findings demonstrate that LB-T is an effective pre-enrichment for detecting Salmonella in various market-available meat analogs.