Nutritional, phenolic, and antioxidant profiles of blueberry genotypes

Blueberry ( Vaccinium spp.) is globally valued for its rich phenolic content and high antioxidant capacity, yet these biochemical traits are known to be highly sensitive to growing environment. This study evaluated the fruit quality, phenolic composition, and antioxidant profiles of ten blueberry genotypes grown under humid subtropical conditions on the southern Caspian coast of Iran. Fruit samples were assessed for soluble solids content (SSC), titratable acidity (TA), SSC/TA ratio, pH, firmness, total phenolic content (TPC), total anthocyanin content (TAC), and antioxidant capacity (DPPH, IC₅₀). Analysis of variance revealed highly significant cultivar effects ( P ≤ 0.01) for all traits except pH. SSC ranged from 11.13 (Bluecrop) to 14.10 °Brix (Jewel), while firmness varied from 1.55 (Chandler) to 3.01 N (Emerald). TPC ranged from 115.67 (Biloxi) to 252.67 mg GAE 100 g⁻¹ FW (Legacy), and TAC from 129.67 (Emerald) to 156.67 mg CGE 100 g⁻¹ FW (Bluecrop). Antioxidant IC₅₀ values ranged from 213.55 (Jewel) to 372.91 µg mL⁻¹ (Bluecrop), demonstrating that high anthocyanin content did not consistently predict strong antioxidant activity. Hierarchical clustering separated cultivars into two distinct groups, with Group 1 characterized by superior sugar–acid balance, firmness, and antioxidant efficiency despite moderate phenolic concentrations. Random Forest analysis identified antioxidant capacity and TPC as the most influential traits for cultivar discrimination. Multi-Trait Genotype–Ideotype Distance Index (MGIDI) analysis ranked Emerald, Jewel, and Misty as the closest to the theoretical ideotype, integrating high sugar content, firm texture, elevated phenolics, and potent antioxidant activity. These findings demonstrate that cultivar-specific quality profiles are not directly transferable across environments and provide evidence-based recommendations for selecting blueberry genotypes suited to humid subtropical regions, with Emerald, Jewel, and Misty emerging as the most promising cultivars for combined nutritional and bioactive quality.