Effect of active essential oils added to chicken tawook on the behaviour of Listeria monocytogenes, Salmonella spp. and Escherichia coli O157:H7 during storage

Abstract

The objective of the study was to assess the antimicrobial effect of active essential oil components (EOs) namely (carvacrol (CA), cinnamaldehyde (CI) and thymol (TH)) on Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7 in chicken tawook during storage at 4 and 10 °C. A marinade consisting of ingredients commonly used in the chicken tawook recipe was prepared and mixed with 1% and 2% v/v CA, CI or TH. The marinade with or without EOs was added to fresh chicken breast cubes inoculated with the foodborne pathogens. Afterward, marinated chicken "tawook" was stored at 4 and 10 °C covered with cling wrap to mimic chill and mild abuse storage conditions for up to 7 days. At 10 °C, the marinade decreased L. monocytogenes numbers on day 4 and 7 by about 2.4 log₁₀ CFU/g as compared to unmarinated samples. Adding EOs to chicken tawook did not change L. monocytogenes numbers during storage at 4 and 10 °C. For Salmonella spp., the marinade decreased the numbers during 10 °C storage on day 4 and 7 by about 4.9 log₁₀ CFU/g as compared to unmarinated samples. At 4 °C, EOs at 2% decreased Salmonella spp. on day 7 by 0.5 log₁₀ CFU/g. One percent CI significantly decreased Salmonella by 1.5 log₁₀ CFU/g, at day 4 of storage. At 10 °C, 1% CA, 2% CI, 1% and 2% TH decreased Salmonella spp. in the samples by 0.5 log₁₀ CFU/g on day 7. The marinade decreased E. coli O157:H7 numbers on the chicken samples during 10 °C storage on day 4 and 7 by about 3.3 log₁₀ CFU/g as compared to unmarinated samples. Regardless of storage day at 4 °C, EOs decreased E. coli O157:H7 populations in chicken tawook by ≤2.4 log₁₀ CFU/g compared to samples without EOs, where the decrease was ≤1.4 log₁₀ CFU/g. Moreover, no significant decrease in E. coli O157:H7 populations could be attributed to the addition of EOs in samples which were stored at 10 °C. Increasing the concentration of EOs from 1 to 2% seemed to have no significant effect in reducing the tested foodborne pathogen populations.

Keywords: Antimicrobial, Carvacrol; Chicken; Cinnamaldehyde; Marinade; Thymol.