Postharvest Quality and Biochemical Changes in Blood Orange Fruit Exposed to Various Non-Chilling Storage Temperatures

Blood oranges grown in subtropical and tropical regions have low anthocyanin levels and a pale internal color at the point of commercial maturity. Since blood oranges are cold-dependent and can enhance anthocyanin during postharvest storage, the effects of various non-chilling storage temperatures (10, 15, and 20 °C) on ‘Moro’ blood orange fruit quality and biochemical changes over a period of up to 42 days were investigated for total anthocyanin concentration (TAC), total phenolic content (TPC), total antioxidant activity (TAA), juice attributes, and physical qualities. Fruit weight and firmness losses increased during storage, with the lowest losses occurring at 10 °C. Titratable acidity (TA) decreased, with the lowest values recorded at 20 °C. Total soluble solids (TSSs) and the TSS/TA ratio increased, with the highest values observed at 20 °C. The sucrose content showed slight changes, while glucose and fructose levels increased during storage, with the highest concentrations of glucose and fructose noted at 20 °C. TAC, TPC, and TAA significantly increased during storage, with the highest values recorded at 10 °C, suggesting upregulation of the fruit antioxidant system and associated bioactive components in response to the lower temperature. Throughout the storage period, peel color parameters, such as L*, b*, C*, and h°, decreased at all temperatures, whereas a*, citrus color index (CCI), and total color difference (ΔE) increased. This study concludes that a storage temperature of 10 °C proved effective in enhancing TAC, TPC, and TAA during storage, as well as in maintaining the other physicochemical attributes.