Location: Produce Safety and Microbiology ResearchTitle: Effectiveness of different antimicrobial washes combined with freezing against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes inoculated on blueberries
|Tadepalli, Shravani - University Of Maine|
|Bridges, David - University Of Maine|
|Driver, Randilyn - University Of Maine|
Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2018
Publication Date: 2/28/2018
Citation: Tadepalli, S., Bridges, D.F., Driver, R., Wu, V.C. 2018. Effectiveness of different antimicrobial washes combined with freezing against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes inoculated on blueberries. Food Microbiology. 74:34-39. https://doi.org/10.1016/j.fm.2018.02.018.
Interpretive Summary: Blueberries are susceptible to microbial contamination. In an effort to reduce foodborne illnesses associated with blueberries, it is important to utilize effective decontamination methods. This study evaluated the efficacy of different sanitizing agents (chlorine-Cl2, chlorine dioxide-ClO2 and lactic acid) when coupled with frozen storage, (-12°C for 1 week) in inactivating foodborne pathogens (Escherichia coli O157:H7, and Salmonella Typhimurium) on blueberries. The results indicated that the combination of chemical treatment and frozen storage was more effective in reducing pathogens than chemical treatments alone. Chemical treatments when combined with frozen storage effectively reduce the risk of contamination from produce. This protocol can be incorporated in suitable processing procedures in the food industry to prevent pathogen contamination.
Technical Abstract: To ensure the microbial safety of produce including blueberries, sanitization is a critical step. This study evaluated the efficacy of sanitizers when coupled with frozen storage, in inactivating Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes inoculated on wild blueberries. Inoculated blueberries were sprayed with sanitizers at different concentrations for different contact times (chlorine -2.5ppm, 5ppm, 10ppm and 15ppm for 10s, 1, 5 and 10min; chlorine dioxide -100ppm, 150ppm and 200ppm for 10s, 1, 5 and 10min; lactic acid-2% and 1% for 5, 10 and 20min). After treatment, one set of blueberries were stored at -12°C for 1 week. Compared to chemical treatments alone, all sanitizers in combination with freezing significantly reduced pathogens (p < 0.05). The greatest reduction of E. coli O157:H7 (4.4 log CFU/g) was achieved by 2% lactic acid with frozen storage. S. Typhimurium had the highest reduction (5.4 log CFU/g) with 200ppm Cl2 in combination with freezing. All three sanitizers with freezing reduced L. monocytogenes to undetectable levels (detection limit <1 log CFU/g). These sanitizers maintained the visual quality of blueberries and did not leave detectable residues. In conclusion, sanitizers when combined with frozen storage effectively reduce the risk of pathogen contamination on blueberries.