Inactivation of Salmonella and Shiga toxin-producing Escherichia coli (STEC) from the surface of alfalfa seeds and sprouts by combined antimicrobial treatments using ozone and electrolyzed water

Authors: MOHAMMAD, ZAHRA - Texas A&M University; KALBASI-ASHTARI, AHMED - Texas A&M University; RISKOWSKI, GERALD - Texas A&M University; Juneja, Vijay; ALEJANDRO, CASTILLO - Texas A&M University

Submitted to: Food Research International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2020
Publication Date: 7/8/2020
Citation: Mohammad, Z., Kalbasi-Ashtari, A., Riskowski, G., Juneja, V.K., Alejandro, C. 2020. Inactivation of Salmonella and Shiga toxin-producing Escherichia coli (STEC) from the surface of alfalfa seeds and sprouts by combined antimicrobial treatments using ozone and electrolyzed water. Food Research International. https://doi.org/10.1016/j.foodres.2020.109488.
DOI: https://doi.org/10.1016/j.foodres.2020.109488

Interpretive Summary: Salmonella and Shiga toxin-producing Escherichia coli were the most common pathogens implicated in outbreaks of foodborne illness that were linked to contaminated alfalfa sprouts. We assessed the effectiveness of a treatment combining ozone and electrolyzed water (AEW) to inactivate Salmonella and STEC on alfalfa seeds and sprouts. Our findings suggest that the use of combined treatment is a feasible intervention to control pathogens on alfalfa seeds and sprouts while maintaining the quality of sprouts. The sprout industry will use these findings to rely on the effectiveness of ozone and AEW in decontaminating alfalfa seeds and sprouts.

Technical Abstract: Many foodborne outbreaks have been associated with consumption of raw alfalfa sprouts. Salmonella and Shiga toxin-producing E. coli (STEC) were the most common pathogens implicated in outbreaks of foodborne illness linked to contaminated alfalfa sprouts. In most outbreaks, the seed was identified as the source of contamination. Individual chemical and non- chemical treatments have failed to eliminate pathogens from alfalfa seeds and sprouts. This study investigated the disinfection of alfalfa seeds and sprouts using a treatment combining ozone with electrolyzed water. Alfalfa seeds inoculated with a cocktail of 3 strains Salmonella and 3 strains of STEC were treated sequentially with aqueous ozone followed by acidic (pH 3.0) electrolyzed water (AEW). The samples were first immersed into 1 L of ozonated water (5 mg/L ozone) for 15 or 20 minutes with continuous oxygen feeding pressurized with 10 psi. The samples then were immersed in 1 L of AEW for 15 min. Salmonella and STEC were significantly (p less than 0.05) reduced by 3.6 and 2.9 log CFU/g on seeds respectively, and by 3.1 and 3.0 log CFU/g reduction on sprouts. There were no significant differences (p more than 0.05) in the magnitude of the log reduction between Salmonella and STEC on seeds and sprouts or between seeds and sprouts. The effect of ozone and AEW treatments on the quality of sprouts including shelf life, weight and color showed no significant changes in sensorial parameters in sprouts as compared to the non-treated controls. The findings suggest that the combination of ozone and AEW is effective in inactivation of Salmonella and STEC on the surface of alfalfa seeds and sprouts with no negative effects on the quality and color of sprouts.