Dissertation
Characterization of the apple peel microbiota: Bacterial and fungal components under environmental, laboratory, and storage conditions
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000002467
Handle:
https://hdl.handle.net/2376/120077
Abstract
Apples are among the most consumed fruit in the United States, but the crop has recently been shown to exhibit some vulnerability to contamination along the supply chain, as evidenced by recent apple-related outbreak and recall events. In contrast to the relatively short duration of harvest and packing activities, apples spend a significant amount of time in the storage environment, up to one year. Many opportunities for contamination exist within this environment that result in significant postharvest losses, with postharvest fungal decay a leading cause. While the initial fungal inoculum is expected to occur in the orchard environment, decay emerges in storage by fungi that necrotize healthy apple tissue. The presence of these necrotic fungal pathogens and the changes induced upon the apple peel environment may support the growth of saprophytic and psychrotrophic foodborne pathogens like Listeria monocytogenes. The 2014 caramel apple outbreak showed the apple’s ability to support the growth of this pathogen under favorable conditions, which usurped the previous thought that apples were a relatively low risk commodity. The environmental shifts that occur on the fresh apple surface across harvest, storage, and production activities affect the microbiome of the apple peel. Given the extended time apples are in storage, the effect that this environment has on the apple surface microbiota has been insufficiently studied. Furthermore, the relationship between postharvest necrotic fungal pathogens and food safety-relevant microorganisms in industry-relevant storage conditions has not been studied in this environment. Additionally, the use of metagenomic methods in fresh produce management has been shown to enhance the industry’s understanding of microbiota of food matrices, but these methods have not been validated for commodities with characteristically low biomass, such as apples. As such, recommendations for enhancing the food safety of fresh apples in these environments is lacking. The evaluation of these relationships using metagenomic methodologies through these experiments has provided insight into the previously poorly studied environment of fresh apple storage and the interactions that occur on the fruit surface and enabled the recommendation of industry practices and interventions to minimize the risks associated with fresh apple production.
Metrics
58 File views/ downloads
79 Record Views
Details
- Title
- Characterization of the apple peel microbiota: Bacterial and fungal components under environmental, laboratory, and storage conditions
- Creators
- Alexis Hamilton
- Contributors
- Faith J Critzer (Advisor)Girish Ganjyal (Committee Member)Ines Hanrahan (Committee Member)Stephanie Smith (Committee Member)Meijun Zhu (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Food Science, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 212
- Identifiers
- 99900606857201842
- Language
- English
- Resource Type
- Dissertation