Optimization of <i>Salmonella</i> Detection in Garlic Granules Using Neutralizer-Aided Enrichment and PMAxx-qPCR

Spices with low water activity (a_w) often contain antibacterial substances that complicate the detection of <i>Salmonella</i> using traditional culture methods. These substances can drive <i>Salmonella</i> into a viable but nonculturable (VBNC) state, rendering it undetectable with culture-based methods. This study aimed to enhance the broth for enriching <i>Salmonella</i> in garlic granules by mitigating the inhibitory effects of antibacterial substances. This study optimized the enrichment broth by using 3× buffered peptone water to increase the buffering capacity of the medium, adding magnesium sulfate and sodium pyruvate to promote the self-repair and recovery of bacteria, and adding DL-dithiothreitol (DTT) and corn oil to neutralize the antimicrobial substances in garlic. Garlic granules were artificially contaminated with <i>Salmonella</i> and subjected to a 2-week desiccation process to simulate low a_w conditions during food storage. The results showed that adding DTT and corn oil as neutralizers in the modified buffered peptone water (mBPW) broth significantly enhanced the detection capability of <i>Salmonella</i> in garlic granules, enabling detection of <i>Salmonella</i> at initial contamination levels as low as 5 CFU/g. In contrast, <i>Salmonella</i> was undetectable without the addition of neutralizers during enrichment. In addition, the optimized mBPW broth was tested on spices other than garlic granules, demonstrating its effectiveness (without neutralizers) in detecting <i>Salmonella</i> in star anise and black pepper. Notably, this study demonstrated that the combination of neutralizer-aided enrichment and PMAxx-qPCR successfully enabled the detection of viable <i>Salmonella</i> in garlic granules. The entire process can be completed in approximately 26 h, demonstrating the method's swiftness and effectiveness in detecting viable cells. This approach provides a fast and sensitive method for the detection of <i>Salmonella</i> in garlic granules, with promising potential for application in similar inhibitory food matrices.