OXIDATIVE GELATION STUDIES OF WATER-SOLUBLE PENTOSANS FROM WHEAT

The gel formation potential of purified wheat water-soluble pentosans and their fractions, arabinoxylan and arabinogalactan, in the presence of H2O2/peroxidase was investigated by small amplitude oscillatory rheological measurements. Gelation proceeded in two stages: a rapid increase in gel rigidity (G´) during the first hour, followed by a much lower rate of gel development thereafter. Disappearance of feruloyl groups coincided with the first stage of the gelation process. Gel permeation chromatography on 8epharose CL-4B and Sephacryl 8-300 revealed that only arabinoxylan actively participated in the network. The rate and extent of gel rigidity development was dependent on polymer and oxidant concentration. Temperature had a negative effect on the gelation process. Gel network development with FeCl3 was similar to that with H2O2/peroxidase, while (NH4)2S2O8 induced gelation at a much lower rate. The cross-linked pentosans and arabinoxylan held up to 100 g of H2O per g of polymer. © 1990, Academic Press Limited. All rights reserved.