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Title: Inactivation of foodborne pathogenic and spoilage microorganisms by 405 nm light : an investigation into potential decontamination applications
Author: McKenzie, Karen
ISNI:       0000 0004 5361 4161
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2014
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The control of microbial contamination in the food industry is critical, as contamination of food produce, surfaces and equipment can lead to acquisition of foodborne infections. Microbial contamination can also result in food spoilage, which can cause both product and financial loss. Consequently novel decontamination technologies are being sought to help reduce contamination. Initial investigations examined the efficacy of 405 nm light for inactivation of a range of common foodborne microorganisms, both in suspension and on agar surfaces. All exposed populations were significantly reduced following 405 nm light exposure. The hypothesised inactivation mechanism involves photoexcitation of endogenous porphyrin molecules within the microorganisms, resulting in production of reactive oxygen species, oxidative cell damage and microbial inactivation. This theory was investigated by exposing fungi to 405 nm light under both aerobic and anaerobic conditions. Results displayed significant reduction in inactivation rates under oxygen depleted conditions, highlighting the critical role of oxygen during 405 nm light inactivation. This study also demonstrated inactivation of bacterial contamination and biofilms on a range of surfaces, demonstrating potential environmental decontamination applications. Further work highlighted the enhanced bacterial inactivation efficacy of 405 nm light when bacteria were exposed under sub-lethal environmental conditions, typical of those present in the food processing industry. Further studies also demonstrated the synergistic effect of TiO2 with 405 nm light, thereby enabling significantly enhanced bacterial inactivation rates. Studies also investigated potential applications for food decontamination and preservation, with preliminary results highlighting successful prevention of spoilage on a range of food products and significant decontamination of E. coli on fresh fruit. This study has confirmed the microbicidal efficacy of 405 nm light, whilst demonstrating a range of potential applications for use within the food industry for improved environmental decontamination. In conclusion 405 nm light has potential to be used safely and effectively as an additional decontamination technology in the food industry.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available