Preparation of pectin from sweetpotato residue and its characterization

The conditions for selective and effective extraction of pectin from sweetpotato residue were es-tablished. Sodium or potassium phosphate solutions of pH 7 or above were suitable for the extraction. The gelatinization of starch in the residue, which interfered with the extraction, was minimized by extraction at 63°C or below. The extract was fractionated into 4 fractions, starch, arabinogalactan and pectin of two types, by DEAE-Toyopearl 650M ion-exchange chromatography. One pectin fraction had two peaks and their molecular weightes were 795, 000 and 167, 000, and that of the other pectin fraction was 278, 000. The uronic acid contents of the two pectin fractions were 82.4 and 92.1%, respectively.