Interactions of organic acids with Salmonella strains from feedlot water-sprinkled cattle

Authors: Beier, Ross; Callaway, Todd; Andrews, Kathleen - Kate; Poole, Toni; Crippen, Tawni - Tc; Anderson, Robin; Nisbet, David

Submitted to: Journal of Food Chemistry & Nanotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2017
Publication Date: 5/8/2017
Citation: Beier, R.C., Callaway, T.R., Andrews, K., Poole, T.L., Crippen, T.L., Anderson, R.C., Nisbet, D.J. 2017. Interactions of organic acids with Salmonella strains from feedlot water-sprinkled cattle. Journal of Food Chemistry & Nanotechnology. 3(2):60-66. https://doi.org/10.17756/jfcn.2017-038.
DOI: https://doi.org/10.17756/jfcn.2017-038

Interpretive Summary: Organic acids like acetic, citric, lactic, and propionic acid are commonly used as a carcass wash to remove bacteria during food production. In this study, the interactions of four organic acids with 145 Salmonella strains comprised of six different serovars obtained from feedlot water-sprinkled cattle were studied. The pH was determined at the molar minimum inhibitory concentrations (MICsm) of the Salmonella strains. Using the determined pH, the concentrations of the undissociated and dissociated organic acids were calculated at the MICsm of the Salmonella strains using the Henderson-Hasselbalch equation. Since all Salmonella strains behaved similarly to the different organic acids, the results of the six different Salmonella serovars Anatum, Cerro, Gaminera, Kentucky, Meleagridis, and Muenster hide and feces strains were treated as a single group for each organic acid, acetic, citric, lactic, and propionic acid. The individual serovar graphs are included in the Supplementary Information. Bacterial inhibition was not solely dependent on pH or on the undissociated organic acid species, but was correlated with the dissociated organic acid species. A small drop in the concentration of the dissociated organic acids may result in a large number of bacteria escaping disinfection. Therefore, an organic acid carcass wash may not provide the expected elimination of surface bacteria if the concentration of dissociated organic acid is not carefully controlled. A concentration of approximately 20 mM dissociated citric, acetic, lactic, and 16 mM propionic acid is suggested to be maintained when disinfecting the Salmonella serovars studied here.

Technical Abstract: Organic acids are commonly used as a carcass wash to remove bacteria during food production. In this study, the interactions of four organic acids with 145 Salmonella strains comprised of six different serovars from feedlot water-sprinkled cattle were studied. The pH was determined at the molar MICs (MICsm) of the Salmonella strains. The concentrations of the undissociated and dissociated organic acids were calculated at the MICsm of the Salmonella strains using the Henderson-Hasselbalch equation. Since all Salmonella strains behaved similarly to the different organic acids, the results of the six different Salmonella serovars Anatum, Cerro, Gaminera, Kentucky, Meleagridis, and Muenster hide and feces strains were treated as a single group for each organic acid, acetic, citric, lactic, and propionic acid. Bacterial inhibition was not solely dependent on pH or on the undissociated organic acid species, but was correlated with the dissociated organic acid species. A small drop in the concentration of the dissociated organic acids may result in a large number of bacteria escaping disinfection. Therefore, an organic acid carcass wash may not provide the expected elimination of surface bacteria if the concentration of dissociated organic acid is not carefully controlled. A concentration of approximately 20 mM dissociated citric, acetic, lactic, and 16 mM propionic acid is suggested to be maintained when disinfecting the Salmonella serovars studied here.