Evaluating palm olein oil for Salmonella control in low-aw, high-fat food processing environments

Over the past five decades, at least 18 major Salmonella outbreaks have been associated with chocolate products. Contamination of chocolate may occur at various stages, from raw material handling to processing and packaging. Due to its high fat content and low water activity, chocolate provides a protective environment for Salmonella at elevated temperatures, posing considerable health risks. Although strict hygiene protocols are implemented in dry production environments, effective cleaning, especially of chocolate transfer pipelines, remains a significant challenge. This study investigated the efficacy of palm olein oil (POo) as a sanitizing agent against Salmonella on surfaces typical of chocolate production lines. Steel coupons were either directly inoculated with a cocktail of four Salmonella serotypes or coated with contaminated chocolate. After a 24 h acclimation period, the coupons were immersed in POo at 20 °C and 92 °C, and bacterial survival was assessed. Immersion in POo at 92 °C resulted in greater than 5-log reduction of Salmonella within 24 h. However, residual cells were detected on the coupons, with complete elimination observed after 7 days. At 20 °C, a 2.5-log reduction was achieved on chocolate-coated surfaces after 7 days, and viable cells were detected in the oil, highlighting a potential risk of cross-contamination through oil recirculation. No significant reduction occurred on surfaces contaminated directly with bacteria at 20 °C. These findings suggest that one-step treatments with hot POo offer practical food-grade and effective methods for killing Salmonella on surfaces of processing equipment, therefore may support in-house validation of cleaning protocols in high-fat, low-moisture food manufacturing settings.