The effect of cold chain disruption on the microbiological profile of chilled chicken meat

This study evaluates the influence of inadequate transport conditions on the microbiological quality of chilled chicken meat packaged in plain and modified atmosphere packaging (MAP). The experiments simulated the temperature increase during sample transport to 8, 11, 14, 17, 20, and 25°C with exposure times of 1, 2, 3, and 4 h. Aerobic plate count (APC), psychrotrophic microorganisms count (PMC), β-D-glucuronidase-positive Escherichia coli, and Salmonella spp. were evaluated immediately after the exposure to the elevated temperature (0 h), 3 h, and 24 h after the return to the temperature of ≤4°C. The upper acceptable limits for APC and PMC were set for each combination of investigated chicken meat and packaging type, taking also the initial bacterial condition into account. Chilled chicken breast samples in plain packaging exceeded the APC limits in 16 cases and PMC limits in 20 cases when exposed to temperatures of >4°C, while only 2 MAP samples exceeded APC limits and 8 samples PMC limits, respectively. In chicken legs, 8 samples in plain packaging exceeded the APC limits and 15 the PMC limits, while 12 samples in MAP exceeded the APC limits and 19 the PMC limits. In 402 samples (31.9%) in which the presence of E. coli was detected, its amount ranged from 1.70 to 3.65 log CFU.g^-1. It was more commonly detected in chicken legs (255 of 630; 40.5%) than chicken breasts (147 of 630; 23.3%) but was not related to exposure temperature, exposure time, or time until examination. The presence of Salmonella spp. was not detected in any of the samples. Data acquired in the presented study will be used in the development of software helping the national supervisory authorities in the Czech Republic to evaluate whether inadequate transport of samples to analytical laboratories could have affected the microbiological profile of the sample.