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Metabolic Trade-Off Between Radical Scavenging Chemotype, Starch Accumulation, and Volatile Aroma Profile in Early- and Late-Maturing Apple Cultivars: Implications for Breeding and Postharvest Quality

Year: 2026

Type: article

Abstract: Apple maturation involves profound metabolic reconfiguration, yet systematic trade-offs among bioactive, primary, and volatile metabolites remain unclear, particularly under highland cultivation. We examined nine apple cultivars spanning early-, mid-, and late-maturing groups grown under identical high-altitude conditions (1950 m). Early-maturing cultivars exhibited superior antioxidant activity, with Huashuo (HS) achieving the highest ABTS•+ radical scavenging (1268.5 μg Trolox/g) and flavonoid (18.9 mg/g) levels. Conversely, late cultivars accumulated significantly more starch (31.5 mg/g in HFS) and total soluble sugars (121.5 mg/g in Ruixue), whereas sucrose peaked in the early Jinyu (94.4 mg/g). PCA and OPLS-DA models robustly separated maturity groups (predictive variance 65.4%). Late-maturing cultivars exhibited reduced volatile abundance, with 338 compounds downregulated versus only 32 upregulated (VIP > 1, p < 0.05). Compounds with high predicted aroma impact (rOAV ≥ 1), including 2,6-nonadienal (Log2FC = −3.21) and isobutyl isovalerate (−3.55), were severely depleted, while butanoic acid propyl ester (5.01) increased. Flavor mapping suggested a marked loss of “green” and “fruity” notes in late cultivars. Overall, highland-grown apples exhibit a fundamental metabolic trade-off favoring starch accumulation, a trait commonly associated with storability in late-maturing cultivars. These findings suggest candidate volatile biomarkers for breeding programs that warrant further validation and highlight the potential need for postharvest metabolic interventions to preserve the natural aroma of late-maturing apples.

Source: Horticulturae

DOI: 10.3390/horticulturae12091048