Impact of sanitizer application on salmonella mitigation and microbiome shift on diced tomato during washing and storage

Authors: Gu, Ganyu; Zhou, Bin; MENDES OLIVEIRA, GABRIELLA - Orise Fellow; REDDING, MARINA - Orise Fellow; Luo, Yaguang - Sunny; Millner, Patricia; Nou, Xiangwu

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2023
Publication Date: 1/20/2023
Citation: Gu, G., Zhou, B., Mendes Oliveira, G., Redding, M., Luo, Y., Millner, P.D., Nou, X. 2023. Impact of sanitizer application on salmonella mitigation and microbiome shift on diced tomato during washing and storage. Postharvest Biology and Technology. https://doi.org/10.1016/j.postharvbio.2023.112268.
DOI: https://doi.org/10.1016/j.postharvbio.2023.112268

Interpretive Summary: Multiple salmonellosis outbreaks in recent years have been associated with the consumption of contaminated whole and diced tomatoes. In this research, ARS scientists evaluated the impact of commonly used and novel sanitizers on the mitigation of Salmonella and shift in indigenous microbiota on diced tomatoes after washing and during storage. Results indicated that application of tested sanitizers in washing significantly reduced the survival of inoculated Salmonella on diced tomato and the occurrence of Salmonella cross-contamination of uninoculated samples. Findings from this research suggest that the new blend containing peracetic acid and a sulfuric acid-surfactant in diced tomato washing could improve the efficacy of Salmonella reduction and cross-contamination prevention, and could extend the product shelf life by suppressing growth of major spoilage bacteria. This research provides insightful information to the produce processing industry.

Technical Abstract: This study examined the shift in Salmonella and indigenous microbiota on diced tomato after washing with three different sanitizers and during post-wash cold storage. Roma tomatoes were inoculated with a Salmonella cocktail (initial level ~ 5.6 CFU/g), diced and washed along with uninoculated diced tomato in simulated flume wash water with sanitizers, including 10 mg/L free chlorine (FC10), 90 mg/L peracetic acid (PA90), PA90 in combination with a proprietary acidified surfactant blend (PS90), and unsanitized control (CK). Salmonella, total mesophilic aerobic bacteria (MAB), and yeast and mold (YM) populations on both inoculated and uninoculated samples were measured before and after washing, and during storage at 4 °C. 16S rRNA amplicon sequencing was also performed to determine the shift in bacterial microbiome. Washing with all tested sanitizers, especially PS90 (> 4 log reduction), reduced Salmonella and MAB populations on inoculated diced tomatoes. Additionally, application of sanitizers significantly mitigated Salmonella cross-contamination onto uninoculated samples. PS90 treatment inhibited the proliferation of most dominant bacteria on diced tomatoes during storage, including Erwiniaceae, Curtobacterium, Pantoea, Erwinia and Enterobacterales, which may benefit product quality and safety.