Evaluation of antioxidant activities, total phenolic content (TPC), and total catechin content (TCC) of 10 sugar apple (Annona squamosa L.) cultivar peels grown in Thailand

Antioxidant activities, total phenolic content (TPC), and total catechin content were analyzed in the ethanol extracts of 10 sugar apple (Annona squamosa L.) cultivar peels grown in Thailand. Antioxidant activity assays carried out in the this study were the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, ferric ion reducing antioxidant power (FRAP), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation scavenging activity, and oxygen radical absorbance activity (ORAC). 'Nhur Thong', 'Nung Keaw', and 'Fai Keaw' showed high percentage fruit peel (over 38.0%). 'Nhur Thong', 'Nung Keaw', and 'Fai Keaw' ethanol extracts possessed high antioxidant capacities in the majority of methods used, and thus could be potential candidate of natural antioxidants. 'Fai Keaw' showed the best activity in the ABTS (1.57 mmol of trolox/g dry sample), FRAP (0.43 mmol of trolox/g dry sample), and ORAC assays (2.84 mmol of trolox/g dry sample), as well as the highest content of TPC (140.4 mg) per gram dry sugar apple peel among the 10 cultivars. TPC showed a positive correlation compared with all antioxidant activity assays. In conclusion, 'Fai Keaw' could be utilized as an excellent phenolic compound source for functional food products.