Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2019
Publication Date: 9/19/2019
Citation: Wang, L., Fan, X., Gurtler, J., Wang, W. 2019. Interaction of gaseous chlorine dioxide and mild heat on the inactivation of Salmonella on almonds. Journal of Food Protection. 82(10):1729–1735. https://doi.org/10.4315/0362-028X.JFP-19-114.
Interpretive Summary: Salmonella outbreaks have been associated with raw almonds. Therefore, the USDA and the Almond Board of California mandate pasteurizing the nuts to attain a minimum of 4-logs (99.99%) reduction of Salmonella. The present study evaluated the combination of gaseous chlorine dioxide and mild heating for the reduction of Salmonella on raw almonds. Results demonstrated that applying gaseous chlorine dioxide at 55 degrees centigrade achieved greater than 4 logs of reduction of Salmonella on almonds. This study establishes the relevant conditions of chlorine dioxide needed to meet the mandatory goal of almond pasteurization.
Technical Abstract: Salmonella on almonds were studied. Almonds, dip inoculated with a two-strain cocktail of attenuated Salmonella Typhimurium, were treated with three different concentrations of ClO2 at ambient temperature (ca. 22 deg C), 45, 50, 55 and 60 deg C for 4 h and >90% relative humidity. Concentrations of ClO2 during treatments were measured and populations of Salmonella were determined following treatments. Results demonstrated that ClO2 at concentrations of >4 mg/L and ambient temperature only reduced populations of Salmonella by 1.46 log CFU/g. With increasing treatment temperature, the efficacy of gaseous ClO2 increased. At 55 and 60 deg C, >1 mg/L ClO2 and 4 h treatments, >4 log CFU/g of Salmonella were inactivated. The >4 log reductions of the bacterium by gaseous ClO2 at 55 deg C was confirmed using a three-strain cocktail of pathogenic Salmonella. Overall, results demonstrated that mild heating is necessary for gaseous ClO2 to achieve >4 log CFU/g inactivation of Salmonella on almonds.