High pressure inactivation of Salmonella on Jalapeño and Serrano peppers destined for direct consumption or as ingredients in Mexican salsa and guacamole

Abstract

In summer of 2008, the United States witnessed one of the largest multi-state salmonellosis outbreak linked to the consumption of Jalapeño and Serrano peppers tainted with Salmonella enterica serovar Saintpaul. The first objective of this study was to assess the application of high hydrostatic pressure (HHP) to decontaminate Jalapeño and Serrano peppers from this pathogen. Jalapeño and Serrano peppers were inoculated with a five-strain cocktail of Salmonella to a final level of ca. ~6logCFU/g and subsequently pressure-treated in the un-wetted, wetted (briefly dipped in water) or soaked (immersed in water for 30min) state at 300–500MPa for 2min at 20°C. The extent of pressure inactivation increased as a function of the pressure level and in the order of soaked>wetted>un-wetted state achieving population reductions ranging from 1.1 to 6.6logCFU/g. Overall, pressure treatment at 400–450MPa (soaked) or 450–500MPa (wetted) for 2min at 20°C rendered Salmonella undetectable. Since salsa and guacamole are two examples of widely consumed Mexican dishes that incorporate raw Jalapeño and Serrano peppers, we subsequently investigated the pressure-inactivation of Salmonella in salsa and guacamole, originating from contaminated peppers used as ingredients. The storage time (0, 12 or 24h) of the condiments prior to HHP as well as the pH (3.8–5.3) and the type of acidulants (vinegar and lemon juice) used all influenced the extent of Salmonella inactivation by HHP. This study demonstrates the dual efficacy of HHP to decontaminate fresh chile peppers destined for direct consumption and minimally process condiments possibly contaminated with raw peppers to enhance their microbiological safety.