Bran arabinoxylan

Based upon these studies, Table III summarizes the partially deduced structure of the mono-, di-, and trisaccharides, obtained by the partial degradation of the original arabinoxylan. These structures may not be completely accurate, because of some uncertainty in the theory used to speculate the mode of linkage. Consequently, each one needs to be isolated to unambiguously verify its structure. These results do, however, provide some indication of the complicated structure of the side-chains of bran arabinoxylan. 

Arabinoxylans is another group of compounds that could be extracted from biomass, and in particular wheat bran. Arabinoxylans is one of the major dietary fibres in wheat, which has numerous applications in bread manufacture, animal feeding and medical applications (Schooneveld-Bergmans, 1999). Hollmann and... 

Agger J, Vrkso-Nielsen A, Meyer AS. (2010). Enzymatic xylose release from pre-treated com bran arabinoxylan differential effects of deacetylation and deferuloylation on insoluble and soluble substrate fractions. J Agric Food Chem, 58(10), 6141—6148. 

Berlanga-Reyes, C., Carvajal-Millan, E., Caire-Juvera, G., Rascon-Chu, AS. Marquez-Escalante, J.A. Martinez-Ldpez, A.L. (2009). Laccase induced maize bran arabinoxylan gels structural and rheological properties. Journal of Food Science and Biotechnology, 18, 1027-1029. 

In contrast to AGX, the GAX consists of an arabinoxylan backbone, which contains about ten times fewer uronic acid side chains than a-L-Ara/ ones, and has some Xylp residues doubly substituted with these sugars. GAX are located in the non-endospermic tissues of cereal grains such as in wheat, corn, and rice bran. The degree and pattern of substitution of GAX appears to vary with the source from which they are extracted. These differences are reflected in the ratio of Ara to Xyl, the content of MeGlcA, and the presence... 

Phenolic acids, and especially ferulic acid, which is abundantly present in cereals, is found esterified to the polysaccharides present in primary and secondary cell walls of plants. Ferulic acid is the major phenolic acid occurring in the cell walls of monocotyledons and appears as cis and the more abundant trans isomers (reviewed in [Klepacka and Forna, 2006]). Ferulic acid is found in wheat, maize, rye, barley [Sun et al., 2001], oats, spinach, sugar beet, and water chesnuts [Clifford, 1999], generally esterified, and rarely as free form, such as in barley [Yu et al., 2001]. It is esterified in primary cell walls to arabinoxylans (Fig. 2.4) in the aleurone layer and pericarp [Clifford, 1999], as in spinach [Fry, 1982] or in wheat bran [Smith and Hartley, 1983], Ferulic acid can also be found esterified to other hydroxycinnamic acids such as in Mongolian medicinal plants where it is found as feruloylpodospermic acid, which is... 

Lindhauer (2005) recently carried out pilot-plant scale trials of an H202-based alkali extraction process, where a product was separated that had a purity of 70-80% arabinoxylans and a yield of 50% of the initial wheat bran. This process is expected to be commercialised as an integrated plant together with bioethanol production. 

Esterases. Acetyl esterase (EC 3.1.1.6) removes acetyl esters from acetylated xylose and short-chain xylo-oligomers. It s polymeracting counterpart, acetyl xylan esterase (EC 3.1.1.72), has a similar activity, but prefers polymeric xylan.244 In addition to acetate-specific enzyme detection kits, HPLC or GC analysis of acetate release from native extracted xylan and chemically acetylated xylan, colorimetric substrates, such as p-nitrophenol acetate and /3-napthyl acetate, or the fluorometric substrate, 4-methylumbelliferyl acetate are also used to assay acetyl esterases.244,253 The third esterase, ferulic acid esterase (EC 3.1.1.73), hydrolyzes the ester bond between ferulic acid or coumaric acid and the arabinose side chain of arabinoxylan. Assays for this activity are usually carried out using starch-free wheat bran or cellulase-treated gramineous biomass as a substrate and monitoring ferulic or coumaric acid released by HPLC or TLC. When preparing enzyme-treated substrates, care must be taken to employ phenolic-acid-esterase-free cellulases.244 Other substrates include methyl and ethyl esters of the phenolic acids, as well as finely ground plant biomass.240,254,255... 

Polysaccharides Arabinoxylans MGN-3 (51) Rice bran enzymatically modified with Hyp-homyceles mycelia HIV HIV replication, Syncytia formation, Increase T B cell mitogen response [42]... 

Ghoneum, M. Anti-HIV Activity in Vitro of MGN-3, an Activated Arabinoxylan from Rice Bran. Biochem. Biophys. Res. Commun. 1998,243, 25-29. 

C. D. Nandini and P. V. Salimath, Structural features of arabinoxylans from sonalika variety of wheat Comparison between whole wheat flour and wheat bran, J. Set Food Agr., 83 (2003) 1297-1302. 

Arabinoxylan Chinese black-grained wheat (bran) 118... 

The wheat bran is an attractive raw material for arabinoxylan production. The arabi-noxylan is the major dietary fiber component of wheat bran. Its extraction from the wheat bran by the ultrasound-assisted enzymatic treatment has been reported by Wang et al. The wheat bran is also an interesting source of glucose, xylose, and arabinose for bioconversion into ethanol. This low-cost residue is efficiently pretreated and hydrolyzed through the combination of nuld physicochemical methods and appropriated enzyme dosages. Thus, glucose to ethanol conversion of 95% was obtained by using Saccharomyces cerevisiae si. ... 

Erangois IE, Lescroart O, Veraverbeke WS, et al. Effects of a wheat bran extract containing arabinoxylan oligosaccharides on gastrointestinal health parameters in healthy adult human volunteers a double-blind, randomised, placebo-controlled, cross-over trial. Br Nutr. 2012 108 2229-2242. 

In contrast to the previous examples, oxidative treatments may promote positive consequences in some other cases, as they decrease concentrations in phenolic acids (and other phenolics) and limit subsequent oxidations. Therefore, hyperoxidation of musts during wine processing has sometimes been proposed, and this process particularly affected HCA derivatives [27]. In addition, a peroxidasic treatment allowed the dimerization of ferulic acid in wheat bran tissues and consequently decreased arabinoxylan solubility and increased mechanical strength of the tissue [58]. 

After the precipitation stage, the final powder from twin screw extmsion (92% dry matter), contains 91% organic matter. The global yield of this process is about 24 % of the potential in hemicelliiloses of wheat bran, if it is considered that arabinoxylans represents 60 % organic matter 26% protein and 5.3% lignin (originating from straw) (table 111). These results should be compared with extraction conditions in the stirred reactor, where the best results are obtained with a molar soda and a L/S ratio of 50. The chemical charge is reduced by a factor of 14 and the L/S ratio by a factor of 15 when twin-screw extruder is used. 

When a stirred reactor is used, the final powder (93% dry matter) contains 90% organic matter. The alcohol precipitation also acts as a purification step during which salts are almost eliminated. The remaining salts are imbedded during the precipitation of hemicelluloses. The global yield of this process is about 59% of the potential in wheat bran hemicelluloses, if arabinoxylans are considered to represent 80% of the organic matter in the final powder (table III). 

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