Structural Differences among Alkali-Soluble Arabinoxylans from Maize (Zea mays), Rice (Oryza sativa), and Wheat (Triticum aestivum) Brans Influence Human Fecal Fermentation Profiles

Abstract

Human fecal fermentation profiles of maize, rice, and wheat bran and their dietary fiber fractions released by alkaline-hydrogen peroxide treatment (principally arabinoxylan) were obtained with the aim of identifying and characterizing fractions associated with high production of short chain fatty acids and a linear fermentation profile for possible application as a slowly fermentable dietary fiber. The alkali-soluble fraction from maize bran resulted in the highest short chain fatty acid production among all samples tested, and was linear over the 24 h fermentation period. Size-exclusion chromatography and (1)H NMR suggested that higher molecular weight and uniquely substituted arabinose side chains may contribute to these properties. Monosaccharide disappearance data suggest that maize and rice bran arabinoxylans are fermented by a debranching mechanism, while wheat bran arabinoxylans likely contain large unsubstituted xylose regions that are fermented preferentially, followed by poor fermentation of the remaining, highly branched oligosaccharides.

Evaluation of the prebiotic potential of arabinoxylans from brewer’s spent grain

“…As already reported by Rose et al (2009), gut microbiota uses a debranching mechanism to metabolise AX making use of bacterial arabinofuranosidases and xylanases (Rose et al 2009). The authors suggested that the highly branched AX promotes the activity of bacterial arabinofuranosidases earlier than the xylanases, in order to remove the arabinose units of the AX side chains enabling the xylanases to reach the xylose backbone (Rose et al 2009).…”

“…Studies reported on the AX fermentation by the human intestinal bacteria indicated that fermentation of AX promotes the growth of Bifidobacterium, Lactobacillus and Eubacterium groups (Cloetens et al 2010;Grootaert et al 2007;Gullón et al 2014;Hughes et al 2007;Pastell et al 2009;Vardakou et al 2008) and, in a smaller extent, also promotes the growth of Bacteroides and Clostridium species (Hughes et al 2007). This process results in the formation of bacterial metabolites such as SCFA and specially the increase of propionic acid concentration (Kabel et al 2002;Napolitano et al 2009;Rose et al 2009). Propionate can be absorbed in the gut, entering in the blood stream and reaching the liver via the portal vein, where it has been associated with reduced cholesterol synthesis and improved insulin sensitivity (Grootaert et al 2007;Neyrinck et al 2011;Van den Abbeele et al 2011), but the mechanisms are not yet fully understood.…”

“…The main cereal source of AX is wheat or wheat bran (Gullón et al 2014;Hughes et al 2007;Pastell et al 2009;Rose et al 2009) due to its high content of AX. Also, and to a less extent, the fermentation of AX was reported in rye (Pastell et al 2009), rice and maize brans (Rose et al 2009) and brewer's spent grain (BSG) (Kabel et al 2002).…”

“…Also, and to a less extent, the fermentation of AX was reported in rye (Pastell et al 2009), rice and maize brans (Rose et al 2009) and brewer's spent grain (BSG) (Kabel et al 2002). The reported differences for these cereals were a consequence of the AX structure, as the fermentation of AX in the colon was influenced by their molecular mass (Hughes et al 2007) and their degree of substitution (Pastell et al 2009;Rose et al 2009). Fermentation of AX from BSG is scarcely reported (Kabel et al 2002) and should be explored further.…”

Dietary Supplementation with Modified Arabinoxylan Rice Bran (MGN-3) Modulates Inflammatory Responses in Broiler Chickens

“…It is suggested that MHN-3 is not digested but is partially absorbed directly into the blood through the intestinal wall to interact with NK cells and macrophages , and then it may modulate the immune responses in not only gut-associated lymphoid tissue but also spleen. Moreover, arabinoxylan from wheat bran inhibits Salmonella colonization in broiler chickens (Eeckhaut et al, 2008), while the different structure was reported among arabinoxy-lan from wheat bran and rice bran (Rose et al, 2010). Hence, it is possible that dietary arabinoxylan rice bran may affect inflammatory responses in chickens.…”