In vitro Colon Fermentation of Soluble Arabinoxylan Is Modified Through Milling and Extrusion

Abstract

Dietary fibers such as arabinoxylan (AX) are promising food constituents to prevent particular diet-related chronic diseases because of their prebiotic properties. Arabinoxylan fermentation by the gut microbiota depends on the structural architecture of AX, which can be modified during food processing and consequently affect its prebiotic potential, but it is little investigated. Therefore, the aim of this study was to evaluate the effects of naturally occurring and processing-induced structural alterations of the soluble AX of wheat bran and rye flour on the in vitro human colon fermentation. It was found that fermentation behavior is strongly linked to the AX fine structure and their processing-induced modifications. The short-chain fatty acid (SCFA) metabolism, acidification kinetics, bacterial growth, and bacterial composition revealed that wheat bran AX (WBAX) was fermented faster than rye flour AX. Increased levels of bound phenolic acids resulting from processing were identified as the inhibiting factor for AX fermentation kinetics. Bacterial genera promoted by AX varied between AX source and processing type, but also between microbiota. Extruded WBAX promoted butyrate production and growth of butyrate-producing Faecalibacterium in the butyrogenic microbiota while it did not enhance fermentation and inhibited the growth of Prevotella in the propiogenic microbiota. We anticipate that the findings of this study are a starting point for further investigation on the impact of processing-induced changes on the prebiotic potential of dietary fibers prior to human studies.

Effects of Co-Modification by Extrusion and Enzymatic Hydrolysis on Physicochemical Properties of Black Wheat Bran and Its Prebiotic Potential

“…Correlated to the SEM micrographs in Figure 2, the loose, porous, and rough surface may provide a higher chance of being utilized by the bacteria [65]. Evidence can be found in the results reported by Demutu et al that extruded and milled WBAX stimulated faster Bifidobacteria growth than the native control [70]. Next, we investigated the prebiotic potential of co-modified BWB by evaluating the abundance of Bifidobacterium and Lactobacillus using simulated intestinal fermentation.…”

“…Correlated to the SEM micrographs in Figure 2 , the loose, porous, and rough surface may provide a higher chance of being utilized by the bacteria [ 65 ]. Evidence can be found in the results reported by Demutu et al that extruded and milled WBAX stimulated faster Bifidobacteria growth than the native control [ 70 ].…”

“…Along with the improvement of colonic beneficial bacteria, co-modification of BWB could also regulate gut microbial metabolism products, which will reduce colonic pH values and further improve beneficial bacteria [ 70 ]. Here, the content of short-chain fatty acids (SCFAs: acetic acid, propionic acid, and butyric acid) and branched SCFAs (isobutyric acid and isovaleric acid) at T0 in the NC was only 1.21, 0.62, 0.15, 0.031, and 0.025 mmol/L, respectively ( Table 7 ).…”

Dietary fiber and polyphenols from whole grains: effects on the gut and health improvements

“…78 In addition, the fermentation behavior of soluble AX in wheat bran and rye flour in the human colon in vitro is closely related to the factors of extrusion, grinding, molecular weight, arabinose/xylan ratio and bound phenolic acids. 79 In vitro fermentation experiments with different genotypes of maize bran AX demonstrated that both the SCFA profile and gut microbiota were altered in a genotype-specific manner, further indicating that fiber structure is highly specific for the gut bacteria to utilize and produce SCFAs. 80 In addition, oat-derived and barley-derived β-glucans yield opposite results in regulating the abundance of intestinal Bifidobacteria in participants of different ages, 81,82 and even the same intervention in similar populations shows interindividual differences in the modulation of the gut microbiota composition, possibly owing to interindividual factors such as baseline microbiota composition and diet.…”

Intestinal permeability and gut microbiota interactions of pharmacologically active compounds in valerian and St. John’s wort

“…In vitro human gut microbiota models inoculated with fecal microbiota and mimicking the physicochemical conditions of the gut are powerful tools to evaluate the xenobiotic-microbiota interactions [10,11]. We previously showed that the artificial microbiota produced with the PolyFermS model inoculated with immobilized fecal microbiota is a reproducible source of large amounts of inocula for high throughput testing and comparison of different treatment conditions, including xenobiotic degradation with the same microbiota background [10,12]. A particular advantage of using the latter is that the amount of inoculum is not limiting and high inoculation ratios (e.g.…”