Effects of Ascorbic Acid and Melatonin Treatments on Antioxidant System in Fresh-Cut Avocado Fruits During Cold Storage

Fresh-cut fruits have a limited postharvest life compared to fresh intact fruits; they have gained considerable market share. In this study, we investigated the effectiveness of melatonin (1 mM) and ascorbic acid (20 mM) treatments, alone or in combination, on qualitative traits and antioxidant systems of fresh-cut avocado fruits during 14 days of cold storage (4 +/- 0.5 degrees C and RH 95 +/- 0.5%). The results showed that the combined melatonin and ascorbic acid treatment delayed colour changes, thereby retarding the ripening process and weight loss compared with separate melatonin and ascorbic acid treatments. Furthermore, melatonin and ascorbic acid treatment showed a synergistic effect on fresh-cut avocado, improving the enzymatic and non-enzymatic antioxidant system during cold storage. Compared with the control, the total polyphenol and flavonoid contents in the treated avocado were increased, and a higher antioxidant activity was observed. The combined treatment improved catalase, ascorbate peroxidase, and superoxide dismutase activities; decreased polyphenol oxidase and guaiacol peroxidase activities; and effectively reduced membrane damage by influencing lipoxygenase activity. These results indicate that the combination of melatonin and ascorbic acid could be a useful, reliable, and eco-friendly postharvest treatment to maintain physicochemical and nutraceutical features, reduce oxidative stress and enzymatic browning, and extend the shelf life of fresh-cut avocado.

Automated summary

The combined use of melatonin and ascorbic acid treatment can delay color changes, slow down ripening process and weight loss of fresh-cut avocado fruits, while improving antioxidant system and increasing polyphenol and flavonoid contents, resulting in higher antioxidant activity.