Developmental Dynamics of Physicochemical Traits, Polyphenols, and Antioxidant Capacity in ‘Dorset’ Apples and Valorization of Unripe Fruits

Fruit development has a strong effect on the biochemical structure and antioxidant activity of apples, especially in warm-climate cultivars. The current experiment investigated the development of physicochemical characteristics, polyphenol accumulation and antioxidant activity in Malus domestica Borkh. cv. Dorsett Golden over eight developmental stages between 42 and 126 days after full bloom (DAFB). Growth parameters were also evaluated, fruit apparent density, moisture content, pH, titratable acidity and reducing sugars alongside biochemical parameters, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity (DPPH, ABTS and FRAP). Fruit apparent density and reducing sugars increased as development progressed and the moisture content peaked at 56 DAFB and then started to decline gradually to maturity. There was a significant developmental difference in the polyphenolic compounds, where TPC reached 24.10 ± 12.47 mg GAE/100 g, and TFC reduced to 125.81 ± 13.95 mg QE/100 g at 126 DAFB. Assay-dependent patterns of antioxidant activity were observed: DPPH and ABTS activities rose throughout ripening whereas FRAP values reduced and were at 0.05 ± 0.01 mmol g ^− 1 . Correlation analysis showed that there were complex relationships between the antioxidant capacity and the phenolic composition. The developmental stages (56–84 DAFB) were characterized by high phenolic levels and high antioxidant potential. These results indicate that immature apples removed during thinning are potentially useful in the production of nutraceutical and functional foods due to the presence of bioactive compounds in them.