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Isoeugenol significantly inactivates Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes in refrigerated tyndallized pineapple juice with added Yucca schidigera extract
- Thomas-Popo, Emalie, Mendonca, Aubrey, Dickson, James, Shaw, Angela, Coleman, Shannon, Daraba, Aura, Jackson-Davis, Armitra, Woods, Floyd
- Food control 2019 v.106 pp. 106727
- Escherichia coli O157, Listeria monocytogenes, Salmonella enterica, Yucca schidigera, agar, minimum inhibitory concentration, pathogens, pineapple juice, refrigeration, sensory properties
- The antimicrobial effectiveness of isoeugenol against Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes in refrigerated (4 °C) pineapple juice (PJ) with added 0.5% (w/v) yucca extract (YEX) was investigated. Sub-lethal injury of pathogen survivors and sensory characteristics of PJ were also evaluated. Samples of PJ with YEX and isoeugenol at 0 (control), 0.50, 0.75, 1.0, or 1.5 μL mL−1 were each inoculated with a five-strain mixture of one pathogen to obtain an initial viable count of ∼7.1 log CFU mL−1. During storage of PJ at 4 °C for 70 days, numbers of non-injured and sub-lethally injured survivors were determined by plating diluted juice samples on selective and non-selective agar. The minimum inhibitory concentration (MIC) of isoeugenol for E. coli O157:H7 and S. enterica was 0.5 μL mL−1 in brain heart infusion broth and the MIC for L. monocytogenes was 0.2 μL mL−1. The minimum bactericidal concentration (MBC) for E. coli O157:H7 and S. enterica was 0.6 μL mL−1 while the MBC for L. monocytogenes was 0.4 μL mL−1. All three pathogens survived for more than 42 days in the control juice. After 2 h, isoeugenol inflicted sub-lethal injury in pathogen survivors. Isoeugenol at 1.5 μL mL−1 completely inactivated E. coli O157:H7 and S. enterica after 4 h and 6 h, respectively (P < 0.05). Within 24 h, all isoeugenol treatments achieved >5 log reduction of each pathogen. However, the PJ samples with isoeugenol at 0.5 μL mL−1 were the only ones acceptable for all sensory attributes evaluated. Isoeugenol (0.5 μL mL−1)/YEX combination has good potential for enhancing the microbial safety of refrigerated PJ without negatively affecting sensory attributes of the juice.