[4-1015-C] Food Safety (1)

[4-1015-C-01] Surface Pasteurisation of Fresh Chicken Meat using UV-C Technology

Arthur Jonathan Philip¹, Negah Nikanjam¹, Emilia Nowak¹, *Anthony Mutukumira¹ (1. Massey University(New Zealand))

Keywords:Chicken, UV-C, Spoilage, Shelf-life

Fresh chicken meat is highly susceptible to surface contamination by spoilage and pathogenic microorganisms. The New Zealand safety standard stipulate that aerobic mesophilic counts (AMCs) present on surfaces of fresh chicken should be <7 log CFU.cm^-2 by end of shelf-life when stored at 4°C. The study investigated the effect of continuous ultraviolet light at 254 nm (UV-C) on the surface of fresh chicken samples. To determine the optimum UV-C parameter, fresh chicken portions (skinless breast fillet, skinless thigh fillet, skin-on breast fillet, and skin-on thigh fillet) were treated with four UV-C dosages (50, 100, 200, and 300 mJ^.cm^-2) at ambient temperature (20°C) using a commercial UV disinfection system. Temperature changes, exposure time and AMCs were determined as the responses. Standard enumeration of AMCs on fresh chicken portions was carried out by swabbing and plating dilutions on agar plate followed by 30°C/72 h incubation. The result indicated that 50 mJ^.cm^-2 UV-C dose had maximum microbial reduction on surfaces of skinless and skin-on chicken samples with minimal temperature changes and lowest exposure times hence, it was selected as the optimum dosage for the two types of fresh chicken samples. The effect of 50 mJ.cm^-2 UV-C dose was then investigated on the surfaces of fresh skinless and skin-on chicken breast samples. Treated samples intended for storage at 4°C/7 days were repackaged. Instrumental color analysis, AMCs, lipid oxidation, and sensory evaluation were conducted during storage (4°C) for 7 days. All the chicken samples were also tested for E. coli, S. aureus, L. monocytogenes, Campylobacter spp. and Salmonella spp. The fresh chicken samples were evaluated for appearance, odor, and texture by 5 semi-trained focus group panelists at 1, 5, and 7 days. Cooked chicken samples were evaluated by consumer sensory panelists (n=30) on days 1 and 7 using the 9-point hedonic rating scale. AMCs on control chicken samples exceeded the national standard on day 5 of storage, whereas UV-treated chicken samples (p<0.05) extended the shelf life to day 6 (skin-on) and day 7 (skinless) by reducing the initial cell counts and 3.80 ± 0.35 log CFU.cm^-2 skinless chicken samples to 3.07 ± 0.34 and 1.87 ± 0.98 log CFU.cm^-2, respectively. Insignificant (p>0.05) differences of microbial counts between the control and UV-treated skin-on samples were found. Tests for the pathogens were negative in all the chicken samples. Although 50 mJ.cm^-2 UV-C dose had no impact (p>0.05) on the color and lipid oxidation of both skin-on and skinless chicken samples, the sensory panelists detected a slight burnt odor of UV-C treated fresh raw chicken samples stored (4°C) for day 1 which was not detected after cooking of the chicken samples that had been stored. The results suggested that 50 mJ.cm^-2 continuous UV-C light (254 nm) chicken surface treatment successfully extended the shelf life by reducing the AMCs on skinless chicken portions compared to the skin-on samples.