Date of Award

Summer 8-2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Food Science

First Advisor

Anuradha Prakash

Second Advisor

Jose de Jesus Ornelas Paz

Third Advisor

Rosalee Hellberg

Abstract

Post-harvest Superficial scald affects the quality of Granny Smith Apples. Oxidative stress develops superficial scald with antioxidant systems mitigating the extent of this damage. This study evaluated the effects of gamma, X-ray, and electron beam irradiation on antioxidants – ascorbic acid, total phenolics, α-tocopherol, carotenoids, chlorophyll, and campesterol – in scalded and non-scalded apple peel tissue. Apples were treated with 0.2-0.77 kGy and stored at 0-1 °C. Irradiation at the applied doses increased scald incidence, suggesting that disruption of antioxidant systems promoted reactive oxygen species accumulation and membrane damage. While certain antioxidants appeared to be upregulated as a stress response, others were depleted. Irradiation significantly reduced ascorbic acid up to 45.7% and campesterol up to 81.6% in a dose-dependent manner, while α-tocopherol increased in electron beam treated apples up to 35.7%. Phenolic content was unaffected by irradiation but was 43.9% lower in scalded compared to non-scalded electron beam-treated apples. Chlorophyll and carotenoids were largely unchanged by either irradiation or scald. These results indicate that irradiation-induced oxidative imbalance may contribute to scald development. New insights into the relationship between irradiation-induced oxidative stress and superficial scald in apples could inform future postharvest handling strategies for maintaining fruit quality during storage.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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Available for download on Thursday, December 04, 2025

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