Characterization of Dietary Fiber Polysaccharides from Dehulled Common Buckwheat (Fagopyrum esculentum) Seeds

Abstract

Buckwheat is a pseudocereal that has gained increasing interest of industry and consumers over the past decade. Little, however, is known about its dietary fiber composition and nonstarch polysaccharide structures. Analysis of the monosaccharide composition indicated large amounts of pectic polysaccharides in both insoluble and soluble fiber from buckwheat. Methylation analysis gave further insights into the structures of the polysaccharides. The corresponding partially methylated alditol acetates suggested only low amounts of galactans. Xyloglucans were the main hemicellulosic polysaccharides in the insoluble fiber fraction. Highly branched arabinans, exclusively substituted at position O3, were of higher abundance. These results were confirmed by screening endo‐arabinanase and endo‐galactanase liberated oligosaccharides with high‐performance anion‐exchange chromatography with pulsed amperometric detection and LC‐MS2. Application of this method also demonstrated highly branched arabinan areas within the pectic polysaccharides. Only low amounts of fiber associated hydroxycinnamic acids and diferulic acids were liberated by alkaline treatment, and no evidence was found for their attachment to polysaccharides, suggesting only a minor impact of these structural elements on fiber structures in dehulled buckwheat seeds.

Detailed Structural Characterization of Arabinans and Galactans of 14 Apple Cultivars Before and After Cold Storage

“…Glycosidic linkages of the non-starch polysaccharides were determined by methylation analysis as described previously ( Nunes et al, 2008 ; Wefers and Bunzel, 2015 ). In brief, the samples were dissolved in DMSO and methylated by addition of freshly ground NaOH and methyl iodide.…”

“…The PMAAs were extracted into dichloromethane, washed, and residual water was removed by freezing overnight at -18°C. Identification of the PMAAs was carried out on a GC-MS system (GC-2010 Plus and GCMS-QP2010 SE, Shimadzu) as described previously ( Wefers and Bunzel, 2015 ). Relative quantification of the PMAAs was carried out on a GC-FID system (GC-2010 Plus, Shimadzu) using the same conditions as for GC-MS analyses.…”

Specific substrate-driven changes in human faecal microbiota composition contrast with functional redundancy in short-chain fatty acid production

“…All analyses were performed in duplicate. To evaluate authenticity and purity of the NDCs used in this study, their monosaccharide composition was analysed by high performance anion exchange chromatography with pulsed amperometric detection after acid hydrolysis as described previously (Wefers and Bunzel, 2015). Details of the hydrolysis conditions for the different NDCs are given in Supplementary Methods.…”

Present status and future perspectives of breeding for buckwheat quality

“…According to an early study by Asano et al (1970), water soluble polysaccharide from buckwheat endosperm consisted of xylose, mannose, galactose, and glucuronic acid. Recently, Wefers and Bunzel (2015) reported that both SDF and IDF from dehulled common buckwheat seeds contained large amounts of pectin, and that xyloglucans were the major hemi-cellulosic polysaccharides in IDF. Izydorczyk and Head (2010) reported differences in the TDF, SDF, and IDF contents in each milling fraction of five buckwheat varieties.…”