Strain-Specific Survival of Salmonella enterica in Peanut Oil, Peanut Shell, and Chia Seeds

摘要

In North America, outbreaks of Salmonella have been linked to low-water activity (a_w) foods, such as nuts and seeds. These outbreaks have implicated an assortment of Salmonella serotypes. Some Salmonella serotypes (e.g., Enteritidis and Typhimurium) cause high proportions of salmonellosis. Nevertheless, there has recently been an emergence of uncommon Salmonella serotypes and strains (e.g., Tennessee, Hartford, and Thompson) in iow-a_w foods. The aim of this study was to evaluate the survival characteristics of Salmonella serotypes Enteritidis, Typhimurium, Tennessee, Hartford, and Thompson in three low-a_w food ingredients with varying a_w: peanut oil (a_w = 0.521 ± 0.003), peanut shell (a_w =0.321 ± 0.20), and chia seeds (a_w = 0.585 ± 0.003). The survival of individual Salmonella strains on each food matrix was monitored for a maximum of 150 days by spreading the bacterial cells onto Luria-Bertani and/or xylose lysine deoxycholate agar. Overall, Salmonella survived for the longest periods of time in peanut oil (96 ± 8 days), followed by chia seeds (94 ± 46 days). The survival period was substantially reduced on the surface of peanut shell (42 ± 49 h), although PCR after 70 days of incubation revealed the presence of Salmonella cells. In addition, Salmonella exhibited a strain-specific response in the three low-a_w foods tested. Salmonella Hartford was identified as highly persistent in all low-a_w food matrices, whereas Salmonella Typhimurium was the least persistent. The current research emphasizes the adaptable nature of Salmonella to low-a_w food ingredients. This may pose additional problems owing to the downstream production of various end products. Additionally, unique survival characteristics among Salmonella strains highlight the need for tailored mitigation strategies regarding high-risk Salmonella strains in the food industry.