Use of Neutralizers to Improve Salmonella spp. Detection in Inhibitory Food Matrices

The use of right sample preparation protocols is critical when analyzing challenging matrices containing inhibitory compounds inhibiting Salmonella growth during pre-enrichment step. The use of right sample preparation protocols will not only avoid a false negative result, but it can also have a huge positive impact on laboratory operations, as it is used for every type of method (cultural, ELISA, or PCR), every day in every laboratory. Sample preparation instructions to overcome the inhibitory effects are limited and for most cases an increase in the dilution factor (i.e., an increase of the volume of pre-enrichment broth). In this study, two neutralizers were identified as suitable alternatives for Salmonella detection in spices, natural flavors, and other food items (coffee, tea). Pre-enrichment with buffered peptone water and activated charcoal is considered the preferred solution, since it is cheaper to use and applicable to a broad range of food items, including coffee, vanilla, allspice, onion, tea, and peppermint with limit of detection between 0.63 and 2.45 cfu/25g whereas other food items like cinnamon and mustard were inactivated by buffered peptone water with cocktail of neutralizers (limit of detection between 0.35 and 1.05 cfu/25g). The use of neutralizers can reduce the analytical cost for Salmonella analysis as well as reducing the amount of reagents used (ranging from 1 L up to 4.5 L per 25-g sample) which will have a positive impact on laboratory operation workload as well as ergonomics and the environment.