Phenolic Composition and Antioxidant Capacities of Chinese Local Pummelo Cultivars' Peel

Abstract

China is one of the main production areas of pummelo [Citrus grandis (L.) Osbeck.] in the world and has lots of distinctive local cultivars. Systematic research on the detection of phenolics and antioxidant capacity of peels of mature local cultivars pummelo fruits is rare. In the current study, phenolic composition and content in peels (flavedo and albedo) of ten Chinese local pummelo cultivars were determined using Ultraviolet Spectrophotometer and High Performance Liquid Chromatography (HPLC), and their antioxidant capacities were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, ferric reducing antioxidant power (FRAP), and 2,2′-azino-bis (3-ethylbenzthiazoline-6)-sulfonic acid (ABTS) methods in the current study. The research not only provides data that support making full use of the resources of Chinese local pummelo cultivars, but also lays the theoretical basis for research of pummelo fruit nutrition and health values. The results showed that the total phenolic (TP) content in albedo was significantly higher than that in flavedo; on the contrary, the total flavonoid (TF) content was lower in the albedo than in the flavedo. C. grandis ‘Hongxinyou’ flavedo contained the highest TP contents, C. grandis ‘Liangpingyou 78-8’ flavedo contained the highest TF contents, and C. grandis ‘Guanxi Miyou’ albedo contained the highest TP and TF contents. Naringenin, hesperetin, diosmin, and gallic acid were the predominant phenolics in the flavedo, whereas hesperetin, diosmin, rutin, chlorogenic acid, and gallic acid were the primary phenolics in the albedo. The flavedo of C. grandis ‘Yubei Shatianyou’ and the albedo of C. grandis ‘Dianjiang Baiyou’ had the highest antioxidant potency composite (APC) indexes. Overall, the ‘Yubei Shatianyou’ flavedo and the ‘Dianjiang Baiyou’ albedo are excellent sources of antioxidants and have the greatest potential value for exploitation and utilization.