Fermentability of Oat and Wheat Fractions Enriched in β‐Glucan Using Human Fecal Inoculation

Abstract

Fermentation by human fecal bacteria of fractions of wheat bran prepared by preprocessing technology were examined and compared with a β‐glucan‐rich oat bran and a purified β‐glucan (OG). The wheat fractions were essentially a beeswing bran (WBA), mainly insoluble dietary fiber, and an aleurone‐rich fraction (WBB) containing more soluble fiber and some β‐glucan (2.7%). The oat bran (OB) had more endosperm and was very rich in β‐glucan (21.8%). Predigestion of WBB and OB to mimic the upper gastrointestinal (GI) tract gave digested wheat bran fraction B (WBBD) and digested oat bran (OBD), respectively. These predigested fractions were fermented in a batch technique using fresh human feces under anaerobic conditions. Changes in pH, total gas and hydrogen production, short chain fatty acids (SCFA), and both soluble and insoluble β‐glucan and other polysaccharide components, as determined from analysis of monosaccharide residues, were monitored. Fractions showed increasing fermentation in the order WBA < WBBD < OBD < OG. Variations in SCFA production indicated that microbial growth and metabolism were different for each substrate. Polysaccharide present in the supernatant of the digests had disappeared after 4 hr of fermentation. Fermentability of oat and wheat β‐glucan reflected solubility differences, and both sources of β‐glucan were completely fermented in 24 hr. Although the overall patterns of fermentation indicated the relative amounts of soluble and insoluble fiber, the anatomical origin of the tissues played a major role, presumably related to the degree of lignification and other association with noncarbohydrate components.

In Vitro Bile-Acid Binding and Fermentation of High, Medium, and Low Molecular Weight β-Glucan

“…Acetate, propionate, and butyrate, the main SCFA formed from in vitro fermentation, were typical metabolites for dietary fiber polysaccharide fermentation (21,29). In addition to the three main SCFA, small amounts of isobutyrate, valerate, and isovalerate were produced (<5-7% of the total) from all treatments, which are the major products of protein fermentation (21).…”

In vitro fermentability of differently digested resistant starch preparations

“…Dy digested samples led to the highest total SCFA and butyrate productions, ba and il digested samples were in a similar range with exception of the lower butyrate production for RS3il. Mean values € SD; n = 2. a) n = 1. resulted in high butyrate ratios after 8 h in vitro fermentation compared to the blank sample as well as to other dietary fiber sources fermented using the same model [27,28].…”

Repeated cooking and freezing of whole wheat flour increases resistant starch with beneficial impacts on in vitro fecal fermentation properties

“…This discrepancy could be due to differences in fecal microbiota composition among studies. Interestingly, in vitro fecal fermentation of arabinoxylans and other cell wall polysaccharides from wheat has shown a propensity toward elevated propionate production in many studies (Rose, Patterson, & Hamaker, 2010;Williams, Mikkelsen, le Paih, & Gidley, 2011;Wood, Arrigoni, Miller, & Amadò, 2002). Perhaps the increase in cooking-freezing cycles improved the fermentation of the other dietary fibers in wheat.…”