Dissertation
INDUSTRIAL SCALE GASEOUS CHLORINE DIOXIDE FUMIGATION TREATMENT ON LOW MOISTURE FOODS – ALMONDS AND WHOLE BLACK PEPPERCORNS
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004578
Handle:
https://hdl.handle.net/2376/125233
Abstract
Contamination of almonds and peppercorns during preharvest and postharvest has raised a safety concern. Contaminations may include spoilage or pathogenic microorganisms like Salmonella, Aspergillus species, and aflatoxin B1 (AFB1). A nonthermal waterless technology must be investigated and integrated into the processing of almonds and peppercorns to control the contamination. Gaseous chlorine dioxide (ClO2) is a selective oxidant and powerful antimicrobial agent for decontaminating low moisture foods. There is a need to evaluate it on reducing a range of microorganisms and validate it from lab-scale to industrial-scale. Therefore, the goal of this research was to develop and validate batch gaseous (ClO2) fumigation to reduce the background and pathogenic microorganisms on whole black peppercorns and almonds, respectively, from lab-scale to industrial-scale. Batch gaseous ClO2 was designed to reduce the background microflora on peppercorns, validate E. faecium as a surrogate for Salmonella, and reduce A. flavus and AFB1 on almond kernels. The effect of gaseous ClO2 was also observed on the genetic defense mechanism of A. flavus. These results were used to develop the gaseous ClO2 fumigation technology on inhull almonds contaminated with A. flavus and background flora without affecting its quality (moisture content, lipid oxidation, and color). Finally, the engineering controls (moisture, gas concentration, flow, sample size, and application method) were assessed and optimized at pilot and industrial scales. Gaseous ClO2 demonstrated significant reductions of background microbial flora (90%) on peppercorns, Salmonella (99%) and E. faecium (97.5%) on almond kernels, A. flavus (99.6%) and AFB1 (84.4%) on kernels, and reductions of A. flavus (87.4%) and background flora (88.8%) on inhull almonds. The results highlighted the influence of external parameters on the ClO2 fumigation efficiency. Multiple pilot-scale treatments were designed using the lab-scale results. The results from pilot-scale treatments were translated into industrial pilot-scale stockpiled inhull almonds fumigation. After industrial pilot-scale treatments, the study recommends the usage of gaseous ClO2 as a postharvest fumigant to control pathogenic microorganisms on inhull almonds to enhance food safety. This information provides a foundation for the scale-up of gaseous ClO2 technology on low moisture foods adapted to commercial processing.
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Details
- Title
- INDUSTRIAL SCALE GASEOUS CHLORINE DIOXIDE FUMIGATION TREATMENT ON LOW MOISTURE FOODS – ALMONDS AND WHOLE BLACK PEPPERCORNS
- Creators
- Bhargavi Rane
- Contributors
- Vivian C.H. Wu (Advisor)Shyam S. Sablani (Advisor)Juming Tang (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
- 244
- Identifiers
- 99900898739801842
- Language
- English
- Resource Type
- Dissertation