Evaluation of Peroxyacetic Acid for Reducing Low Levels of Salmonella on Laboratory-Inoculated and Naturally Contaminated In-Shell Hazelnuts.

In-shell hazelnuts may be exposed to many sources of Salmonella during harvest and postharvest processing. Chemical sanitizers, such as peroxyacetic acid (PAA), are used by some postharvest processors in an attempt to reduce microbial loads; however, data are limited on its efficacy to reduce Salmonella on in-shell hazelnuts under conditions relevant to the industry. This study analyzed the efficacy of PAA to reduce small numbers of Salmonella on laboratory-inoculated (3.9 most probable number [MPN] per hazelnut) and naturally contaminated in-shell hazelnuts (8.2 MPN/33 g). Batches of hazelnuts (333 to 1,500 g) were agitated in water or PAA (80 or 200 ppm) for 1 min. Inoculated hazelnuts were analyzed for the presence of Salmonella on an individual nut basis. Naturally contaminated hazelnuts were analyzed for the presence of Salmonella in larger sample sizes (33 g). Water and PAA (80 ppm) were effective at reducing Salmonella contamination on laboratory-inoculated hazelnuts (untreated, 85.5% positive; water, 38.7%; and PAA, 29.5%). Neither water nor PAA treatments (80 and 200 ppm) were effective in reducing Salmonella on naturally contaminated hazelnuts. The use of PAA in wash lines is unlikely to reduce Salmonella contamination on in-shell hazelnuts; however, PAA may reduce cross-contamination during postharvest washing activities.