Purification and characterization of anthocyanin from Irish wild blackberry: impact on color, composition, and antioxidant capacity

Abstract The extraction of anthocyanins from fruits and food waste using eco-friendly techniques has gained attention. This study, for the first time, used Amberlite XAD-7 resin to purify Irish wild blackberries, known for their high polyphenol and anthocyanin content. Ultrasound-assisted extraction (UAE) with 60% ethanol at 325 W for 7.5 min was employed. The crude extract (BCE) was purified with resin to remove impurities while retaining anthocyanins. The total phenolic content (TPC) was 9.35 ± 0.07 mg GAE/g for BCE and 8.82 ± 0.33 mg GAE/g for the purified extract (BPE). Total anthocyanin content (TAC) was 0.21 ± 0.01 mg CYE/g for BCE and 0.15 ± 0.01 mg CYE/g for BPE. HPLC identified cyanidin-3-glucoside (C3G) as the dominant anthocyanin. The C3G concentration was 5.50 ± 0.02 mg/g in BCE and 4.01 ± 0.01 mg/g in BPE at 520 nm. Antioxidant capacity assessed via CUPRAC, FRAP, and DPPH assays showed significant differences between BCE and BPE in CUPRAC (25.13 ± 1.09 mg AAE/g for BCE vs. 23.06 ± 0.26 mg AAE/g for BPE), with no significant differences in FRAP and DPPH assays. Amberlite XAD-7 resin effectively removed impurities while preserving antioxidant capacity, making BPE a potential ingredient for pharmaceutical and food applications due to its concentrated anthocyanin content, thereby introducing a novel approach in the field. Graphical Abstract