Dissertation
SCALING UP GASEOUS CHLORINE DIOXIDE TREATMENTS FOR REDUCTION OF PATHOGENS IN FRESH PRODUCE
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004559
Handle:
https://hdl.handle.net/2376/125194
Abstract
Fresh produce can be contaminated by foodborne pathogens before consumption. But they are sensitive to thermal treatments. There is a need for effective non-thermal interventions for the industry to enhance produce safety and reduce deadly outbreaks. The objectives of this study were to 1) investigate the inactivation kinetics of gaseous ClO2 on bacteria inoculated on baby carrots (as a food model) and evaluate potential surrogate cocktails at lab scale for future validation studies in manufacturing plants; 2) assess the efficacy of gaseous ClO2 inactivation of Listeria innocua (L. innocua) on fresh apple surfaces under controlled atmosphere (CA) conditions in lab-scale units to prototype the commercial cold storage settings and evaluate the possible negative impact on fruit quality after regular atmosphere (RA) cold storage, 3) study the effectiveness of gaseous ClO2 on the inactivation of L. innocua on fresh apple with pilot-scale and semi-industrial scale RA cold storage surfaces and evaluate the overall fruit quality post-treatment, 4) investigate the stress response of L. monocytogenes on Fuji apple surfaces when exposed to gaseous ClO2 to help understand the antimicrobial mechanisms of gaseous ClO2 and determine the optimal treatment conditions. A non-linear trend of gaseous ClO2 inactivation was observed in pathogenic and surrogate Escherichia coli and Salmonella. A potential surrogate cocktail was validated to represent pathogens’ behavior under gaseous ClO2 conditions. More than 2.5 log reductions of L. innocua were achieved by batch gaseous ClO2 treatments for apples under CA conditions at ambient temperature for 1 h, which did not adversely affect (P>0.05) apple quality. Significant (1.4±0.2 and 1.2 log CFU/mL) reductions of L. innocua (P<0.05) were achieved by 1-month pilot-scale and 3-month semi-industrial scale gaseous ClO2 treatments, respectively, in the cold storage (4℃) of fresh apples without negatively affecting the fruit quality. The gene expression of two relevant virulence (hly) and stress (clpC) genes of L. monocytogenes were downregulated during the stress by gaseous ClO2. The findings of this study provide the foundation to implement gaseous ClO2 treatment in commercial cold storage, which offers critical food safety benefits for the fresh apple industry by reducing the risk of pathogen contamination during storage.
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Details
- Title
- SCALING UP GASEOUS CHLORINE DIOXIDE TREATMENTS FOR REDUCTION OF PATHOGENS IN FRESH PRODUCE
- Creators
- Jiewen Guan
- Contributors
- Vivian C.H. Wu (Advisor)Juming Tang (Advisor)Shyam S. Sablani (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Biological Systems Engineering
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 219
- Identifiers
- 99900898639901842
- Language
- English
- Resource Type
- Dissertation