Application of novel technologies for controlling pathogens and spoilage microorganisms in poultry meat

Chicken meat is considered a highly perishable matrix and a potential vehicle of various foodborne pathogens, particularly Campylobacter spp. Therefore, novel control strategies can aid the poultry industry in dealing with these food safety and quality challenges. Ultraviolet (UV) light-emitting diodes (LEDs) technology has emerged as a potentially efficient decontamination approach for application in the agri-food sector compared to conventional UV lamps. The aim of this thesis was to investigate UV-LED technology to better understand its role as a decontamination strategy to reduce foodborne pathogens and spoilage microorganisms in chicken meat without changing fresh meat quality and sensory attributes. A series of 6 studies were conducted in order to achieve this objective. The first study evaluated the use of this technology to inactivate C. jejuni in a liquid medium at wavelengths of 280, 300 and 365 nm and combinations and assessed its decontamination effectiveness through predictive modelling survival curves. The second study investigated the susceptibility of 8 C. jejuni clinical and farm isolates to UV-LED exposure. Different levels of inactivation between the studied strains was observed and genomic changes related to UV light exposure were analysed using whole genome sequencing (WGS). Biofilm formation and susceptibility to ethanol and surface cleaners were also studied in these C. jejuni strains following UV exposure to investigate any potential phenotypical changes. The third study evaluated the efficacy of this technology to reduce the microbial load (total mesophilic and psychrophilic bacteria, total Enterobacteriaceae, Pseudomonas and lactic acid bacteria) on chicken meat and investigated its impact on quality parameters including pH, texture and colour after exposure and during subsequent storage for 7 days at 4 ̊C. Thus, the most germicidal UV wavelength and UV dose were selected to reduce the microbial load by more than 1 log CFU/g on chicken meat without affecting colour, pH and texture of chicken meat. The fourth study investigated the impact of UV light, cold plasma, and plasma activated water (PAW) technologies on the fatty acid profile (FAP) of raw chicken breasts (diced and minced meat) using different treatments. These technologies were shown to not have an impact on fatty acid groups and nutritional quality indices of chicken meat. The fifth study explored the combined effect of the UV-LED technology treatment with refrigerated storage of chicken breast meat over 7 days on C. jejuni, Salmonella enterica serovar Typhimurium, total viable counts (TVC) and total Enterobacteriaceae counts (TEC). Levels of C. jejuni and S. Typhimurium were significantly reduced by the effect of UV-LED during the 7-day storage period. Similar decontamination effectiveness was found for both technologies to reduce TVC and TEC. Moreover, the impact of UV-LED and UV lamp devices on the microbial community composition of chicken meat during storage was further examined using 16S rRNA gene amplicon sequencing. The UV lamp was found to have the greatest impact on the bacterial profile of chicken meat compared to the UV-LED device. Finally, the sixth study compared the impact of the conventional UV lamp and UV-LED on the colour, pH, lipid and protein oxidation of chicken meat stored at 4 °C for 10 days. Slight changes were observed in colour, pH and protein oxidation of chicken samples subjected to UV lamp and UV-LED. To evaluate these changes from a consumer perspective, samples from the different treatments were stored at 4 °C for 3 days and colour likeness, odour likeness and overall appearance were assessed by consumer sensory analysis. However, alterations in quality parameters of chicken meat caused by UV light did not decrease overall acceptance in the sensory analysis. UV-LED was the preferred chicken meat by the participants, even compared to non-treated meat.