Synergistic effect of back-to-back treatment with two different low-dosage antimicrobial washes in combination with frozen storage increases Salmonella Typhimurium and Listeria monocytogenes reduction on wild blueberries

Authors: TADEPALLI, SHRAVANI - University Of Maine; Bridges, David; ANDERSON, RYAN - University Of Maine; ZHANG, RONG - University Of Maine; Wu, Vivian

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2019
Publication Date: 3/18/2019
Citation: Tadepalli, S., Bridges, D.F., Anderson, R., Zhang, R., Wu, V.C. 2019. Synergistic effect of back-to-back treatment with two different low-dosage antimicrobial washes in combination with frozen storage increases Salmonella Typhimurium and Listeria monocytogenes reduction on wild blueberries. Postharvest Biology and Technology. 102: 87-93. https://doi.org/10.1016/j.foodcont.2019.03.013.
DOI: https://doi.org/10.1016/j.foodcont.2019.03.013

Interpretive Summary: Blueberries are susceptible to microbial contamination and to reduce foodborne illnesses associated with blueberries. Therefore, it is important to utilize effective decontamination methods. This study developed an efficient and practical sanitization strategy that implements multiple antimicrobial wash “hurdles” using practical industrial treatment times in combination with freezing (at -17°C for 1 week) with frozen storage, (-12°C for 1 week) in inactivating foodborne pathogens (Salmonella Typhimurium and Listeria monocytogenes) on blueberries. The results indicate that the combination of hurdle antimicrobial treatments combined with frozen storage is effective to reduce pathogen levels down to unrecoverable amounts. This system can be incorporated in suitable processing procedures in frozen fruit industries to help prevent incidences of foodborne illness.

Technical Abstract: To increase the safety of fruits and vegetables, including blueberries, this study developed an efficient and practical sanitization strategy that implements multiple antimicrobial wash “hurdles” using practical industrial treatment times in combination with freezing (at -17°C for 1 week) against Listeria monocytogenes and Salmonella Typhimurium on blueberries. To note synergistic effect of antimicrobial washes, a portable conveyer belt equipped with double spraying system was used to spray multiple treatment solutions at low concentrations on blueberries Bacterial enumeration was then subsequently conducted before and after freezing. The double spraying treatments including chlorine-lactic acid and chlorine-chlorine dioxide resulted in elimination of both pathogens below the detection limit (detection limit < 1 log CFU/g) after freezing. Every combination of treatment followed by freezing resulted in > 4 log CFU/g reduction of both pathogens. Therefore, the food safety margin of frozen fruits and vegetables can be increased by incorporating this sanitization strategy into the existing processing protocols.