Enhancement of postharvest nutritional quality and antioxidant capacity of peach fruits by preharvest oxalic acid treatment

• Oxalic acid treatment enhanced antioxidant activity of peach fruit.
• Oxalic acid treatment increased total phenols, flavonoids and total antioxidant in peach fruit.
• Oxalic acid might be a powerful treatment for delaying the softening process, improving the functional properties and maintaining quality of peach fruit.

To improve the postharvest nutritional quality and antioxidant potential of peach fruit, the fruits were treated with oxalic acid (OA) by preharvest spray at 15 day before harvest. Fruit nutritional quality was analyzed in weekly intervals during the storage of peach fruits at 1 °C for 28 days. The results showed that the application of OA significantly enhanced antioxidant enzymes catalase, peroxidase and superoxide dismutase activities in peach fruits during cold storage. In addition, the increases in total flavonoids, phenolics, and antioxidant activity were higher in treated than in control ones, leading to fruit with high bioactive compounds and antioxidant potential assayed by 1, 1-diphenyl-2-picrylhydrazyl and ferric reducing antioxidant power methods. At the end of storage period, the highest value of total flavonoids among the applied treatment was observed in OA 5 mM. During storage the softening rate was higher in non-treated fruit. Thus, preharvest treatments with OA could be promising strategy to maintain fruit quality and antioxidant capacity as well as maintain a high flesh firmness following post-harvest storage and export.