Comparative Studies of Limonin and Naringin Distribution in Different Parts of Pummelo [Citrus grandis (L.) Osbeck] Cultivars Grown in Thailand

Abstract

Seven pummelo cultivars: Kao Numpueng (KNP), Thong Dee (TD), Kao Paen (KP), Kao Yai (KY), Tha Knoi (TK), Kao Tanggwa (KTG) and Pattavee (PV) grown under Thai pummelo fruit conditions were selected for comparative studies on the distribution of limonin and naringin in various parts of the fruit. In this study, the highest amount of limonin was detected in the seeds of all cultivars. Lesser amounts were detected in albedo followed by flavedo, segment membranes and juice. The limonin content in the seeds ranged from 1375.31- 2615.30 ppm, with the lowest amount in the juice being 10.07–29.62 ppm. The limonin in albedo in decreasing order of cultivars was: TK, TD, KTG, KNP, PV, KY and KP (352.72-133.58-ppm). The limonin in flavedo in decreasing order of cultivars was: PV, TD, KP, KNP, TK, KTG and KY (295.49-130.16 ppm), while in segment membranes the decreasing order of cultivars was: PV, KTG, KNP, TD, KY, KP and TK (293.14–85.81 ppm). Naringin was found in a greater amount than limonin in all fruit parts of the cultivars studied. The order of fruit parts that contained naringin in a decreasing amount was: albedo, flavedo, segment membranes, seeds and juice. The order of cultivars containing naringin in the albedo in a decreasing amount was: KTG, KNP, KP, KY, TK, PV,
TD (28,508.01–10,065.06 ppm). In the flavedo in decreasing amounts, the cultivar order was: PV, KTG, KNP, KP, KY,TD and TK (8,964.24–2,483.96 ppm), while in the segment membranes the decreasing order was: KTG, KY, TD, TK, PV, KP and KNP (4,369.50–1,799.48 ppm). In the seeds, the decreasing
order was: PV, KTG, KNP, TD,and KP (426.66- 257.87 ppm). In the juice, the decreasing order was: PV, TK, KY, TD, KNP, KP and KTG (386.45–242.63 ppm). The chemical composition of the pummelo juice samples showed a high content of ascorbic acid in the range of 37.03–57.59 mg/100ml. The total soluble solids range was 7.14–9.45 OBrix, the titratable acidity range was 0.38–0.98(g/100ml) as citric acid, and the pH range was 3.69–4.05.