Essential oil emulsions as postharvest sanitizers to mitigate salmonella cross-contamination on peppers

Abstract

Alternative postharvest sanitizers to chlorine are of increasing interest for many organic growers and consumers. An emulsion of clove bud oil (CBO; 0.2 and 0.5%) or thyme oil (0.2 and 0.5%) was evaluated as a sanitizer for produce washing against a five-serovar cocktail of Salmonella on snacking peppers and compared for antimicrobial efficacy with sodium hypochlorite (200 ppm). To further evaluate these compounds, the sanitation efficacy of an emulsion was examined after the addition of 1% organic load (OL). Emulsion treatments at 0.2 and 0.5% thyme oil and 0.5% CBO were the least effected by OL and effectively reduced cross-contamination of Salmonella on clean peppers, in many cases to below the limit of detection (1 CFU/10 g; P, 0.05). Chlorine and 0.2% CBO were rendered ineffective by the addition of OL in preventing cross-contamination and performed similarly to the water control. For surface-inoculated peppers, none of the evaluated treatments performed better than a water-only wash. The antimicrobial efficacy of the essential oil emulsions in the presence of OL indicates these emulsions may be suitable replacements for chlorine in postharvest produce wash systems.