Monosaccharide Composition of Sweetpotato Fiber and Cell Wall Polysaccharides from Sweetpotato, Cassava, and Potato Analyzed by the High-Performance Anion Exchange Chromatography with Pulsed Amperometric Detection Method

The cell wall materials (CWMs) from sweetpotato (Ipomoea batatas cv. Kokei 14), cassava (Manihot esculenta), and potato (Solanum tuberosum cv. Danshaku) and commercial sweetpotato fiber as well as their polysaccharide fractions were analyzed for sugar composition by the high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) method. The separation of arabinose and rhamnose, and xylose and mannose, by this method has been improved using a CarboPac PA 10 column. Pretreatment of the CWMs and cellulose fractions with 12 M H2SO4 was required for complete hydrolysis to occur. Commercial sweetpotato fiber was found to be mainly composed of glucose (88.4%), but small amounts of other sugars were also detected. Among the root crops, sweetpotato CWM had the highest amount of pectin and galacturonic acid. Fucose was detected only in cassava CWM and its hemicellulose fraction, while galactose was present in the highest amount in potato CWM. Among the polysaccharide fractions, it was only in the hemicellulose fraction where significant differences in the sugar composition, especially in the galactose content, were observed among the root crops. Keywords: Cell wall material; monosaccharide analysis; HPAEC-PAD; dietary fiber; sweetpotato (Ipomoea batatas); cassava (Manihot esculenta); potato (Solanum tuberosum); hemicellulose; pectin