Investigation of Limonoids, Flavanones, Total Polyphenol Content and Antioxidant Activity in Seven Thai Pummelo Cultivars

Abstract

Juices from seven pummelo cultivars: Kao Numpueng (KNP), Thong Dee (TD), Kao Pean (KP), Kao Yai (KY), Tha Khoi (TK), Kao Tanggkya (KTG) and Pattavee(PV) were selected for measurement of limonoids, flavanones, polyphenol content and antioxidant activity. Two limonoids were identified as limonin and nomilin. The limonin in pummelo juices ranged from 29.62 to 10.07mg/L, with the decreasing order of cultivars being TD, TK, KNP, KY, PV, KP and KTG. The nomilin ranged from 41.83 to10.90 mg/L, with the decreasing order of cultivars being TK, KY, KNP, PV, KP, TD and KTG. The total limonoid ranged from 20.97 to 67.35 mg/L. Nine flavanones were identified: naringin, eriocitrin, neoeriocitrin, narirutin, neohesperidin, hesperidin, didymin, poncirin and quercetin. The last three were not found in all of the cultivars, whereas naringin and neoeriocitrin were found in all of them, with naringin being the major flavanone in all cultivars. The naringin content ranged from 386.45 to 242.63 mg/L, with the decreasing order of cultivars being PV, TK, KY, TD, KNP, KP and KTG. The total flavanones ranged from 245.63 to 393.96 mg/L. The antioxidant capacity was measured by DPPH and FRAPS assays, which gave good correlations with the total polyphenol content. The pink cultivars (TK and TD) had better antioxidant capacity than the white ones (KNP, KY, PV, KP and KTG). Therefore, these pink cultivars can be preferentially used for dietary prevention of cardiovascular diseases and are suitable for industrial processing.