Preharvest Melatonin and Postharvest Xanthan Gum Coating Maintain the Quality of Orlando Tangelos during Storage

Abstract

This study aimed to determine the effects of preharvest spraying of melatonin and postharvest immersion in xanthan gum on the quality and postharvest performance of Orlando tangelo mandarin fruits. After selecting suitable and uniform trees, melatonin foliar spraying was performed at three different concentrations: 0,100 μM, and 200 μM. Foliar spraying was performed one month before harvest and was repeated three times at weekly intervals. Furthermore, the fruits were immersed in two different concentrations of xanthan gum (0.1% and 0.2%) postharvest, these fruits were stored in a cold room at 5 ± 1 °C. Evaluation of fruit characteristics was carried out at the time of harvest and after 45 and 90 days of cold storage. The results showed that foliar spraying of melatonin at a concentration of 100 μM showed the highest weight and pulp of the fruit. Furthermore, melatonin treatment resulted in higher levels of ascorbic acid and increased fruit acidity compared to the control. During storage, fruits treated with melatonin and xanthan coatings showed better quality than those of the control. At the end of the experiment, the lowest weight loss was observed in fruits treated with 200 μM melatonin + 0.1% xanthan. The highest ascorbic acid content was observed in the 100 μM melatonin +0.1% xanthan. The maximum antioxidant activity was observed in 100 μM and 200 μM +0.1% xanthan and also 100 μM melatonin alone. In general, the findings suggest that preharvest foliar spraying and the postharvest application of xanthan coatings can be effective strategies for maintaining Orlando tangelo quality during cold storage.

Keywords

• citrus
• melatonin
• spraying
• storage
• xanthan gum