UTILIZATION OF PULSED ULTRAVIOLET LIGHT AS A MICROBIAL REDUCTION INTERVENTION ON RAW CHICKEN
Open Access
- Author:
- Cassar, Joshua Robert
- Graduate Program:
- Animal Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- October 19, 2018
- Committee Members:
- Edward William Mills, Thesis Advisor/Co-Advisor
Jonathan Alexander Campbell, Committee Member
Ali Demirci, Committee Member - Keywords:
- chicken
pulsed ultraviolet light
Salmonella
E. coli
Campylobacter - Abstract:
- As the world population continues to increase, so does the occurrence of foodborne illness outbreaks. Globally, one out of ten individuals are infected and become ill after consuming contaminated food. A growing global population has resulted in an increased requirement for high quality, dietary protein. In response, the demand and consumption of poultry has increased since the 1960’s, with anticipated growth to continue through 2030. Currently, poultry products are associated with over 16% of all foodborne illness outbreaks in the United States. Despite the constant efforts to reduce pathogens in poultry products, contamination of poultry products by various pathogens still occurs. Antimicrobial interventions aim to reduce the presence of pathogens on poultry products. Pulsed ultraviolet (PUV) light, a novel technology to the food industry, has emerged as a potential alternative to current microbial reduction interventions. A depth of research has shown the ability of PUV light to reduce the presence of pathogens on food. The USDA Food Safety and Inspection Service has established performance standards for chicken parts with a maximum acceptable presence for Salmonella and Campylobacter. A non-thermal and non-chemical process, PUV light may be a more effective alternative to current interventions. Therefore, this research was undertaken to evaluate PUV light treatment for the decontamination of the surface of chicken products. In the first phase of this research, the effectiveness of PUV light as a surface decontamination process on chicken thighs was evaluated using a static PUV light system. Skinless and skin-on chicken thighs were surface inoculated with 6-7 log10 cfu/cm2 of Escherichia coli, Salmonella and Campylobacter, in separate trials. PUV light treatment variables included the distance from the quartz window of the PUV light (8 and 13 cm) and time of exposure (0, 5, 15, 30, and 45 seconds) which provided total energy between 0 and 62.2 J/cm². Microbial reductions were evaluated by comparing treated samples to untreated controls. Increased exposure to PUV light resulted in an increased (p<0.05) reduction of E. coli, Campylobacter and Salmonella. Treatment by PUV light for 5 and 45 seconds on lean surface thighs resulted in log10 cfu/cm2 reductions of 1.2 and 2.0 for E.coli, 1.5 and 2.2 for Campylobacter, and 1.6 and 2.4 for Salmonella, respectively. Skin-on chicken thighs treated by PUV light for 5 and 45 seconds resulted in log10 cfu/cm2 reductions of 1.2 and 2.0 for E.coli, 1.1 and 1.9 for Campylobacter, and 0.9 and 1.8 for Salmonella, respectively. In the second phase of this project, a pilot scale pulsed UV system was used to evaluate the effectiveness of PUV light as an antimicrobial intervention on various chicken parts. The system consisted of two PUV light chambers mounted above an adjustable conveyor belt. Prior to treatment, boneless/skinless (B/S) chicken breasts, B/S thighs and bone-in/skin-on thighs were inoculated with ~8 log10 cfu/cm2 concentration of E. coli. Total energy (J/cm2) delivered to the surface of the chicken parts was considered the main treatment variable leading to microbial reductions. The conveyor was set at 10 cm below the quartz window of the two PUV light units and total energy values (5, 10, 20, 30 J/cm2) were achieved by adjusting conveyor speed. Two passes under the PUV lights, one conveyor pass for the top and one for the bottom were utilized for each of the three types of chicken parts tested. Treated samples were evaluated against untreated samples to quantify microbial reduction as a result of PUV light. Increased total energy of PUV light resulted in increased (p<0.05) reductions of E. coli on all parts. Exposure to PUV light at 5 and 30 J/cm2 resulted in log10 cfu/cm2 reductions of 0.34 and 0.94 for B/S breasts, 0.29 and 1.04 for B/S thighs and 0.10 and 0.62 for bone-in/skin-on thighs, respectively. The last phase of this research, using the same pilot scale PUV light system, evaluated quality attributes of chicken parts before and after treatment. B/S chicken breasts, B/S thighs and bone-in/skin-on thighs were treated with 30 J/cm2 of PUV light. Lipid and protein oxidation were measured and recorded at 0, 24, 48 and 120 h after the pulsed light treatment. Concentrations of malonaldehyde (MDA) were used as the indicator for lipid oxidation. PUV light treatment did not increase (p>0.05) the concentration of MDA in chicken breast of thigh samples. Time was significant (p<0.05) in contributing to the development of MDA in both treated and untreated samples. Treated and untreated chicken parts averaged 3.20 to 5.17 ug of MDA per 10 g for B/S breasts, 2.60 to 4.26 ug of MDA per 10 g for B/S thighs and 3.73 to 8.86 ug of MDA per 10 g for bone-in/skin-on thighs, at 0 and 120 h respectively. When evaluating products for protein oxidation, carbonyl content was used as the indicator for oxidation. PUV light did not increase (p>0.05) the occurrence of protein oxidation (free carbonyl concentration) in chicken breast or thigh samples. CIELAB color space, L*, a*, b* parameters were used to evaluate the color changes of samples after PUV light treatment. L*, a*, and b* values of B/S breasts, B/S thighs and bone-in/skin-on thighs did not significantly (p>0.05) change as a result of PUV light treatment. In conclusion the results of this research, demonstrate that PUV light has the capability to reduce the presence of pathogenic microorganisms on the surface of raw chicken without contributing to adverse quality effects. More research is needed to evaluate the effect that PUV light has on sensory quality and shelf life. Constraints, such as, surface temperature rise of the product needs to be addressed prior to commercial application.