Document Type : Research paper
Authors
1
Department of Food Science and Technology, Quchan branch, Islamic Azad University, Razavi Khorasan, Iran
2
Department of Food Science and Technology, Quchan branch, Islamic Azad University, Quchan, Iran
3
Horticultural Science Research Institute, Citrus and Subtropical Fruits Research Center, Agricultural Research Education and Extension Organization (AREEO), Ramsar, Iran
10.22059/ijhst.2025.391816.1045
Abstract
The post-harvest deterioration of orange fruit quality, including weight loss and changes in biochemical attributes, which is exacerbated by drought stress and can be influenced by pre-harvest treatments and storage conditions. This two-year study (2021-2022) analyzed the contribution of pre-harvest foliar applications of chitosan (500 ppm) and melatonin (100 µM), individually and in combination, on the post-harvest quality of ten-year-old ‘Valencia’ and ‘Thomson Navel’ orange trees under well-watered and water-stressed (40% FC) conditions. The experiment, conducted at a commercial citrus orchard in Sari, Iran, employed a factorial experiment based on RCBD design with irrigation levels and foliar treatments as pre-harvest factors. During the post-harvest stage, fruits were stored for 0, 30, 60, and 90 d under either traditional or modified atmosphere packaging (MAP: 10% CO2, 5% O2, 85% N2) at 5 °C. Results indicated a significant increase in weight loss of fruit, reaching a minimum of 118.1 g for ‘Valencia’ and 175 g for ‘Thomson Navel’ after 90 d. Additionally, total soluble solids increased during storage, while MAP effectively mitigated weight loss. Drought stress further decreased fruit weight and TSS. However, chitosan and melatonin, particularly when used together, inhibition of loss of weight. The combined treatment resulted in the smallest weight reduction (3.08%) in ‘Valencia’ oranges after 30d. Antioxidant enzyme activities (DPPH,APX,SOD,POX,PPO, and PAL) generally increased with storage, but MAP decreased DPPH, SOD, and POX activities, while increasing APX and PAL. For instance,the highest DPPH activity (52.64%) was observed after chitosan application. Drought stress and chitosan/melatonin increased antioxidant enzyme activity.
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