Effect of Antimicrobial Compounds on the Survival and Pathogenic Potential of Acid-Adapted <i>Salmonella</i> Enteritidis and <i>Escherichia coli</i> O157:H7 in Orange Juice

Background: The consumption of unpasteurized fruit juices poses a food safety risk due to the survival of pathogens such as <i>Salmonella</i> Enteritidis and <i>Escherichia coli</i> O157:H7. Methods: This study evaluated natural antimicrobials (nisin, coumaric acid, citral, s...

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Main Authors: Maria Belén Bainotti, Pilar Colás-Medà, Inmaculada Viñas, Isabel Alegre
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Antibiotics
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Online Access:https://www.mdpi.com/2079-6382/14/4/335
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Summary:Background: The consumption of unpasteurized fruit juices poses a food safety risk due to the survival of pathogens such as <i>Salmonella</i> Enteritidis and <i>Escherichia coli</i> O157:H7. Methods: This study evaluated natural antimicrobials (nisin, coumaric acid, citral, sinapic acid, and vanillin) in orange juice as a strategy to ensure the control of these pathogens during the preservation of the non-thermally treated juices. Results: The addition of nisin, coumaric, or citral did not alter the juice’s physicochemical characteristics, ensuring product quality. Nisin (1–2 mL/L), coumaric acid (0.25–0.5 g/L), and citral (0.25–0.5 mL/L) were the most effective in reducing bacterial populations. The antimicrobial activity of the most effective compounds was then tested against both acid-adapted and non-acid-adapted bacteria in refrigerated juice, applying Weibull and linear decay models to assess bacterial inactivation. Non-acid-adapted <i>S.</i> Enteritidis showed a rapid 5 log reduction after 30 h of refrigeration with the highest nisin dose, while the acid-adapted strain exhibited a smaller reduction (2 and 1.5 log units for 1 and 2 mL/L, respectively). Citral was effective but excluded due to solubility and aroma concerns. Non-acid-adapted <i>E. coli</i> O157:H7 showed a 5 log reduction with coumaric acid at 0.5 g/L, whereas acid-adapted strains exhibited a lower reduction (around 1.5 log units). Nisin and coumaric acid also reduced bacterial survival in gastrointestinal tract simulations. However, acid-adapted bacteria were more resistant. Conclusions: These findings highlight the potential of these antimicrobials for food safety applications, though further studies should explore their mechanisms and combinations for enhanced efficacy.
ISSN:2079-6382