Molecular and functional properties of a xylanase hydrolysate of corn bran arabinoxylan.

Enzymatic hydrolysis of arabinoxylans to prepare arabinoxylo-oligosaccharides has been of high interest from the commercial point of view. However, some arabinoxylans, such as those extracted from corn bran, tend to be difficult to hydrolyze into oligosaccharides due to their highly branched structure which limits the action of xylanases. This research presents a new arabinoxylo-oligosaccharide preparation by enzymatic treatment of corn bran with an endoxylanase enzyme. The native arabinoxylan had a molecular weight of 253kDa and the hydrolysate polymers ranged from 51.6 to 132kDa. The hydrolyzates showed improved solubility in contrast to the original sample. The molecular properties of the hydrolyzates were related to the enzyme concentration used in the hydrolysis process, with increasing enzyme concentration leading to decreasing molecular weight and size. Solution viscosity of the samples also decreased with increasing enzyme concentration. All of the hydrolyzates showed emulsifying ability that was comparable to the original arabinoxylan.

Rheology and microstructure of gels based on wheat arabinoxylans enzymatically modified in arabinose to xylose ratio.

BACKGROUND: Arabinoxylans (AX) are polysaccharides consisting of a backbone of xyloses with arabinose substituents ester-linked to ferulic acid (FA). The arabinose to xylose ratio (A/X) in AX may vary from 0.3 to 1.1. AX form covalent gels by cross-linking of FA but physical interactions between AX chains also contribute to the network formation. The present study aimed to investigate the rheological and microstructural characteristics of gels based on AX enzymatically modified in A/X. RESULTS: Tailored AX presented A/X ranging from 0.68 to 0.51 and formed covalent gels. Dimers of FA content and elasticity (G') increased from 0.31 to 0.39 g kg-1 AX and from 106 to 164 Pa when the A/X in the polysaccharide decreased from 0.68 to 0.51. Atomic force microscopy images of AX gels showed a sponge-like microstructure at A/X = 0.68, whereas, at lower values, gels presented a more compact microstructure. Scanning electron microscopy analysis of AX gels show an arrangement of different morphology, passing from an imperfect honeycomb (A/X = 0.68) to a flake-like microstructure (A/X = 0.51). CONCLUSION: Lower A/X values favor the aggregation of AX chains resulting in an increase in di-FA content, which improves the rheological and microstructural characteristics of the gel formed. © 2017 Society of Chemical Industry.

Antiobesity Effect of Exopolysaccharides Isolated from Kefir Grains.

Physiological properties of water-soluble exopolysaccharides (EPS) and residues after EPS removal (Res) from the probiotic kefir were determined in high-fat (HF) diet-fed C57BL/6J mice. EPS solutions showed rheological properties and lower viscosity compared to those of ß-glucan (BG). EPS significantly suppressed the adipogenesis of 3T3-L1 preadipocytes in a dose-dependent manner. Mice were fed HF diets containing 5% EPS, 5% BG, 8% Res, or 5% microcrystalline cellulose (control) for 4 weeks. Compared with the control, EPS supplementation significantly reduced HF diet-induced body weight gain, adipose tissue weight, and plasma very-low-density lipoprotein cholesterol concentration (P < 0.05). Res and BG significantly reduced body weight gain; however, reduction in adipose tissue weight was not statistically significant, suggesting that the antiobesity effect of EPS occurs due to viscosity and an additional factor. EPS supplementation significantly enhanced abundance of Akkermansia spp. in feces. These data indicate that EPS shows significant antiobesity effects possibly via intestinal microbiota alterations.

Suppression of Psyllium Husk Suspension Viscosity by Addition of Water Soluble Polysaccharides.

Psyllium seed husk is an insoluble dietary fiber with many health benefits. It can absorb many times its weight in water, forming very viscous suspensions, which have low palatability and consumer acceptance. We report here a novel approach for decreasing its viscosity, involving inclusion of a soluble polysaccharide in the suspension. This leads to a drastic decrease (up to 87%) in viscosity of suspensions, while maintaining the same dosage level of psyllium and also delivering a significant amount of soluble dietary fiber such as corn bio-fiber gum in a single serving. Four soluble polysaccharides with a range of molecular weights and solution viscosities have been studied for their viscosity suppression effect. Besides improving palatability, another advantage of this approach is that it makes it possible to deliver 2 different dietary fibers in significant quantities, thus offering even greater health benefits.