ABSTRACT
The combined effect of essential oils (EOs): oregano (0.1% v/w) or thyme (0.5% v/w) and the bacteriocin nisin (500 IU/g) on shelf life extension of fresh chicken meat stored at 4oC was investigated over a 20 day storage period. The following parameters were monitored: microbiological (total viable counts (TVC), Pseudomonas spp., Brochothrix thermosphacta, Enterobacteriaceae and lactic acid bacteria (LAB)), physico-chemical (pH, thiobarbituric acid test (TBA), color) and sensory (odor and taste) attributes. Microbial populations were reduced up to 2.8 log cfu/g for a given sampling day (day 6), with the more pronounced effect being achieved by the combination of nisin and thyme essential oil at concentration of 0.5% v/w. The TBA values for all treatments remained lower than 1 mg malondialdehyde (MDA)/kg of meat throughout the 20 day storage period. The pH values varied between 6.4 (day 0) and 5.9 (day 20). The L* parameter values decreased with time. Color parameters a* and b* were not affected by all treatments. Finally, sensory analysis showed that both EOs at the concentrations used, resulted in a desirable odor and taste of the product. Based primarily on sensory evaluation and secondarily on microbiological data, shelf life was 6 days for the control samples and samples treated with nisin, 9 days for samples containing 0.1% oregano EO or nisin plus 0.1% oregano EO and 12 days for samples containing 0.5% thyme EO or nisin plus 0.5 % thyme EO.
