Comparison of Chlorophyll, Carotenoid, and Alpha-tocopherol in E-beam, Gamma, and X-ray Treated 'Granny Smith' Apples
This study aimed to investigate the impact of phytosanitary radiation modality on the lipophilic antioxidants in peels of ‘Granny Smith’ apples. Freshly harvested ‘Granny Smith’ apples were treated with gamma (0.2 kGy), X-ray (0.495 kGy), and e-beam (0.77 kGy) radiation and stored in air at 1 ⁰C for up to four months. Non-irradiated apples were used as control fruit. Peels of irradiated and non-irradiated apples were collected and quantified for chlorophyll, carotenoids, alpha-tocopherol, and antioxidant capacity. The results indicated that gamma irradiation significantly reduced the chlorophyll content by 76% but did not impact X-ray and e-beam-treated apple peels, even though the dose delivered for the latter two was higher. Carotenoid concentrations were initially unchanged but increased in all samples by 55-77% during storage, with X-rays exhibiting the greatest increase. The alpha-tocopherol content remained unaffected by irradiation treatments and storage time. Antioxidant capacity, measured using the DPPH and ABTS methods, was initially unchanged by irradiation but decreased overall during storage, with the control sample exhibiting the greatest reduction. Overall, irradiation reduced chlorophyll and increased carotenoids during storage, which suggests a postharvest yellowing of apples, a negative effect of radiation on the postharvest quality of this fruit. Irradiated fruit showed higher antioxidant capacity than control fruit after four months, and the higher content of carotenoids might partially explain this beneficial effect of irradiation. The results suggest a differential effect of gamma, e-beam, and X-ray treatment on the antioxidant quality of fruit.
Irradiation, lipophilic antioxidants, vitamin E, postharvest, Food Science
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