Submitted to: Carbohydrate Polymers
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/17/2008
Publication Date: 10/29/2008
Citation: Simkovic, I., Yadav, M.P., Zalibera, M., Hicks, K.B. 2009. Chemical modification of corn fiber with ion-exchanging groups. Carbohydrate Polymers. 76:250-254. Interpretive Summary: Corn fiber is an abundant byproduct produced from the industrial corn wet milling process. Each year, over 4 million tons of this material are produced. Most of the corn fiber makes its way into low valued cattle feed and therefore, does not generate much income for corn processors or growers. We are using this corn fiber as a starting feedstock to produce more valuable and functional food and industrial ingredients and materials. In this work, we modified the chemical structure of corn fiber for the first time, by adding on positively and/or negatively charged groups. These new materials were isolated and their structures were elucidated. These new materials will now be tested in future studies to determine their value as components of biodegradable films, paper coating agents, industrial gums and emulsifiers. These studies may lead to new valuable products that can be sold, creating new markets for this low value corn fiber. This should benefit corn growers and processors and users of the new products.
Technical Abstract: Pretreated corn fiber was chemically modified with quaternary ammonium group or/and sulfonated with 3-chloro-2-hydroxypropanesulfonic acid under vacuum or at ambient pressure. The soluble fraction was dialyzed through 1 kDa MWCO dialysis tubing and the material retained inside the tubing was filtered through 10 kDa membrane to separate into fractions with molar mass of 1-10 kDa and greater than 10 kDa. The yield of solubilized material of molar mass higher than 10 kDa (47%) and 1 – 10 kDa (17%) obtained by sulfonation in the presence of NaOH under vacuum was greater than the yields of the treatment at the ambient pressure (43 and 2%) and also in experiments run with only KOH (40 and 5%) or NaOH (38 and 5%) at ambient pressure. The sugar analysis of all soluble fractions indicated that they were typical glucuronogalactoarabinoxylans containing 46-57% D-xylose, 25-33% L-arabinose, 6-12% D galactose, 1-6% D-glucose, up to 8% glucuronic acid, and a trace amount of D-rhamnose, L fucose and D-galacuronic acid in some samples. The linkage of ion-exchanging groups was confirmed by MALDI-TOF-MS and NMR spectroscopy.