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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Research » Publications at this Location » Publication #133954
Title: CELL WALL HYDROXYCINNAMATES IN WILD RICE (ZIZANIA AQUATICA L.) INSOLUBLE DIETARY FIBER

Author
item BUNZEL, MIRKO - U. HAMBURG
item ALLERDINGS, ELLA - U. HAMBURG
item SINWELL, VOLKER - U. HAMBURG
item Ralph, John
item STEINHART, HANS - U. HAMBURG

Submitted to: European Food Research and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cereals provide dietary fiber, an important nutritional commodity used for human/animal foods. We have found that so-called "ferulates" in plant fibers cross-link polysaccharides providing structural strength but limiting the availability of the polysaccharides for digestion. Wild rice is a more limited cereal but has some unique health benefits and a potent antioxidant activity. We studied this only as a part of a larger study on cereal grains, but it seemed to have large amounts of another potential cross-linking agent, sinapic acid, as confirmed and quantified here. In a subsequent paper we will be demonstrating the new cross-linking mechanism for the fiber in this grain that has now been found at lower levels in the more traditional cereal grains as well. Since cereals are an important source of dietary fiber, a knowledge of the contributions of cross-linking agents and antioxidants will help nutritionists elucidate their roles in some of the healthful properties of fiber, such as regulation of blood sugar, lowering of cholesterol, prevention of bowel cancer, etc. Such studies are aimed at understanding the limitations to fiber digestibility, and providing a basis for improving plant utilization and agricultural sustainability.

Technical Abstract: The contents of ester-linked phenolic acids in wild rice (Zizania aquatica L.) dietary fibre were quantified by HPLC analysis, and oligosaccharide hydroxycinnamates were isolated and identified to investigate the linkages of hydroxycinnamic acids to cell wall polymers. In wild rice insoluble dietary fibre (WRIDF) ferulic acid was the most abundant phenolic acid (3942 micro-g/g), but significant amounts of sinapic acid (518 micro-g/g) and p-coumaric acid (142 micro-g/g) were also detected. Treatment of WRIDF with carbohydrate hydrolases or trifluoroacetic acid released several oligosaccharide hydroxycinnamates. After fractionation with Amberlite XAD-2, five feruloylated oligosaccharides were isolated by gel chromatography and semipreparative HPLC and identified as arabinoxylan ferulate fragments. The feruloylated tetrasaccharide {[5-O-(trans-feruloyl)][O-beta-D-Xylp-(1>2)]-O-alpha-L-Araf-(1>3)}-O-beta-D-Xylp-(1>4)-D-Xylp was isolated for the first time from edible plant material. Although some results indicated that sinapic acid is also (at least partially) linked via an ester-bond to polysaccharides, isolation of defined oligosaccharide sinapates was not achieved.