Dissertation
Quality and shelf life of tree nuts
University of the Sunshine Coast, Queensland
Doctor of Philosophy, University of the Sunshine Coast
2019
DOI:
https://doi.org/10.25907/00666
Abstract
Global trade in tree nuts has grown substantially in the last 10 years and is now worth more than US$32 billion annually. A key reason for this growth is the increasing awareness of the health benefits of tree nuts, as they help to reduce cholesterol levels, and reduce incidences of cardiovascular disease, diabetes and some forms of cancer. Tree nuts can lose their quality during postharvest processing, and quality and shelf life are critical issues in the nut industry. Quality refers to the ability of a product to meet users' expectations whilst shelf life is the time food remains in a state that is acceptable for the consumer, or considered safe for consumption. The quality of tree nuts can change rapidly after harvest because of their high oil content and high levels of unsaturated fatty acids. The major cause of quality deterioration in tree nuts is lipid oxidation. There is a need to develop methods that can rapidly assess nut quality in real-time during postharvest processing and storage. The general aims of my thesis were to: (1) review and analyse factors that affect the quality and shelf life of tree nuts, and (2) test the potential of hyperspectral imaging to predict nut kernel quality. A review of the literature found that the quality and shelf life of tree nuts are affected by temperature, moisture content, relative humidity, oxygen concentration, light, harvest time, fatty acid composition, cultivar and product type, i.e. nut-in shell or kernel. The most critical factors are storage conditions, harvest time and cultivar. The optimum storage temperature of tree nuts ranges from 5°C to 15°C depending on species. In general, tree nuts harvested late in the harvest season have reduced kernel oil quality. The review also identified that there are no universally accepted quality standards for tree nuts. In addition, the review found that there is a lack of rapid quality assessment methods for tree nuts.
Details
- Title
- Quality and shelf life of tree nuts
- Authors
- Tsvakai Gama
- Contributors
- Helen M Wallace (Supervisor)
- Awarding institution
- University of the Sunshine Coast
- Degree awarded
- Doctor of Philosophy
- Publisher
- University of the Sunshine Coast, Queensland
- DOI
- 10.25907/00666
- Organisation Unit
- School of Science and Engineering - Legacy; University of the Sunshine Coast, Queensland; GeneCology Research Centre - Legacy
- Language
- English
- Record Identifier
- 99450817702621
- Output Type
- Dissertation
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