Fermentation capacities of fructan‐ and pectin‐rich by‐products and purified fractions via an in vitro piglet faecal model

Abstract

BACKGROUND Dietary strategies such as the inclusion of prebiotics have been suggested for modulating intestinal microbiota. In piglets, this strategy could result in a reduction of post‐weaning‐associated disorders and the use of antibiotics. To date, mainly purified fractions have been tested for their prebiotic effects at weaning while trials of potential health‐promoting effects of products and corresponding by‐products remain rare. In this study, fructan‐ and pectin‐based ingredients have been tested in a two‐step in vitro model for their fermentation kinetics as well as for their short‐chain fatty acid production and microbiota profiles in fermentation broth as indicators for their prebiotic activity. RESULTS Chicory root, in contrast to chicory pulp, exhibited an extensive and rapid fermentation similar to inulin and oligofructose, although butyrate levels of root and pulp did not reach those of the purified fractions. Chicory pulp showed higher relative levels of Lactobacillus spp., Bifidobacterium spp., Clostridium cluster IV and butyryl‐CoA:acetate‐CoA transferase gene abundance compared to chicory root. Sugar beet pulp, orange and citrus by‐products displayed extensive gas fermentation patterns, equivalent to those of purified pectin, and revealed an elevated butyrate production compared to purified pectin. Moreover, several orange and citrus by‐products displayed significantly higher relative levels of Bifidobacterium spp. in comparison to purified pectin. CONCLUSIONS Chicory root and pulp as well as orange and citrus by‐products appear to be promising ingredients for piglet diets for modulating intestinal fermentation for health purposes. © 2019 Society of Chemical Industry

In vitroprebiotic potential of agricultural by-products on intestinal fermentation, gut barrier and inflammatory status of piglets

“…Chicory root, with a higher ratio of soluble to insoluble polysaccharides and the soluble fraction being mainly composed of fructans, is highly fermentable and therefore is more likely to be fermented at the end of the small intestine (55) . Chicory pulp displayed slower fermentation kinetics which is related to its high insoluble fibre content (high NDF and ADF levels) and its low amount in fructans, mainly composed of polysaccharides with high polymerisation degree (30) . This supports the hypothesis that the rapidity and extensiveness of the fermentation are modulated by the fructan content of the ingredient which was already demonstrated by Shim et al (56) and Pellikaan et al (57) and previous experiments (30) .…”

“…An overview of the bacterial populations present in the FS of all tested ingredients is presented in online Supplementary Fig. S1 and was mainly used as selective criteria for the present study, along with the previous data (30) .…”

“…The ingredients were studied using a modified three-step in vitro model of the pig's gastro-intestinal tract (35) combining an enzymatic hydrolysis and dialysis to a batch fermentation with faecal microbiota. The grinded ingredients underwent a pepsinpancreatin hydrolysis adapted from the protocol of Boisen & Fernández (36) as described by Uerlings et al (30) followed by a dialysis step according to Kalala et al (37) .…”

“…Fermentation broths sampled after 6, 12 and 24 h of fermentation (n 6 fermentation vials) were analysed by isocratic HPLC using the Alliance System e2695 (Waters) with an Aminex HPx-87H column (BioRad) as described by Uerlings et al (30) . A calibration curve with known concentrations of SCFA and lactate was used to quantify the amounts present in the samples.…”

“…Microbiota profile kinetics were measured after 6, 12 and 24 h of fermentation (n 3 fermentation vials). Genomic DNA from fermentation broth samples was extracted using the QIAamp DNA Stool Mini Kit (Qiagen) following the manufacturer's instructions adapted by Uerlings et al (30) . The DNA concentration and quality were, respectively, determined by Nanodrop (Thermofisher Scientific Nanodrop 2000) and agarose gel (1 %).…”