Rice bran represents a reservoir of largely underutilized functional biopolymers that may be mobilized for improved food, feed, and nutraceutical uses. Soluble arabinoxylan and oligosaccharide fragments isolated from rice bran fiber have been implicated to function as biological response modifiers, providing healthful benefit to consumers. Arabinoxylan is largely immobilized within the insoluble fiber fraction through dehydrodiferulate and lignin-ferulate cross-links. Ferulate moieties are ester-linked at the O-5 position of arabinofuranoside side-branches (linked O-2 and/or O-3) along the (1β→4) xylopyranose backbone. To support investigation of putative immunomodulatory activities in the colon by rice bran arabinoxylan, we have isolated gram quantities of “hemicellulose B” fractions from rice bran fiber following sequential alkali extraction. We have similarly isolated this fraction by a separate extraction with dilute alkaline hydrogen peroxide, providing conditions to retain ferulate esters. We will present our results obtained for preparing hemicellulosic fractions, for determining their linkage structure and compositions, and for comparing oligosaccharide profiles generated from them following treatment with a monocomponent GH11 xylanase.

Structure, composition, and oligosaccharide profiles for hemicellulosic polysaccharides isolated from rice bran fiber

255th National Meeting (2018)

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