Production of Glucose, Galactose and Mannose from the Skins of Durian and Mangosteen

In this study, production of glucose, galactose and mannose from the skins of tropical fruits, durian and mangosteen was carried out. Those sugars were obtained by acid hydrolysis of micro-crystalline cellulose and polysaccharide rich-fractions of the samples. The micro-crystalline cellulose (MCC) rich-fractions were purified using nitric acid-acetic extraction while polysaccharide rich-fractions were obtained using aqueous-acetone precipitation method. The hydrolysates consist of glucose, galactose, mannose and other sugar residues were analyzed its total sugar/carbohydrate contents and monosaccharide composition using phenol-sulfuric acid and pre-column derivatization HPLC techniques, respectively. The results indicated that yields of glucose that obtained from the MCC of durian skins is 14.23 % of the dried skin of durian compared to 8.52 % of glucose from the MCC of mangosteen skins. The yields of glucose, galactose and mannose from the polysaccharides of the durian and mangosteen skins are very low, which are 0.98, 0.70 and 0.16 % of the dried skin of durian, respectively. While 0.23 % glucose, 0.18 % galactose and 0.17 % mannose were determined from the polysaccharide fraction of mangosteen skins. Results proposed that durian and mangosteen skins are feasible for the production of bioethanol from plant wastes.