Comparative Phenolic Profiling and Antioxidant Activity of Peel and Flesh in Four Apple ( Malus domestica Borkh.) Cultivars From Northwest Iran

Phenolic compounds are major contributors to the antioxidant capacity of apple fruit; however, their accumulation is strongly influenced by both genetic background and fruit tissue. Integrated evaluations combining global bioactive indices with detailed phenolic profiling across apple cultivars and tissues grown under identical agro‐climatic conditions remain limited. This study investigated four apple cultivars: Golden Delicious, Red Delicious, Mashhad, and Braeburn grown in Northwest Iran. The peel and flesh tissues were analyzed for total phenolic content (TPC), total flavonoid content (TFC), anthocyanin concentration, and antioxidant activity using the DPPH radical scavenging assay. Individual phenolic compounds were identified and quantified by high‐performance liquid chromatography (HPLC), and multivariate analyses were applied to explore relationships among traits. Significant cultivar‐, tissue‐, and cultivar × tissue–dependent differences were observed for all measured parameters ( p < 0.05). Red Delicious exhibited the highest phenolic richness and antioxidant capacity, with TPC values reaching 98.7 mg GAE g −1 DW and the lowest IC 50 values (15.9 μg·mL −1 ). Peel tissues consistently accumulated higher phenolic levels than flesh, showing up to 2–4‐fold greater antioxidant activity across cultivars. Chlorogenic acid was the dominant phenolic acid, while flavonol composition displayed pronounced cultivar specificity. These results demonstrate that phenolic accumulation and antioxidant performance in apple fruit are jointly regulated by cultivar and tissue specialization. Apple peel, particularly from phenolic‐rich cultivars such as Red Delicious, represents a valuable plant‐based source of natural antioxidants with potential applications in functional foods and nutraceutical products.