Fermentation In Large Intestine Research Articles

Exploring the bioaccessibility of polyphenols and glucosinolates from Brassicaceae microgreens by combining metabolomics profiling and computational chemometrics

Microgreens constitute natural-based foods with health-promoting properties mediated by the accumulation of glucosinolates (GLs) and phenolic compounds (PCs), although their bioaccessibility may limit their nutritional potential. This work subjected eight Brassicaceae microgreens to in vitro gastrointestinal digestion and large intestine fermentation before the metabolomics profiling of PCs and GLs. The application of multivariate statistics effectively discriminated among species and their interaction with in vitro digestion phases. The flavonoids associated with arugula and the aliphatic GLs related to red cabbage and cauliflower were identified as discriminant markers among microgreen species. The multi-omics integration along in vitro digestion and fermentation predicted bioaccessible markers, featuring potential candidates that may eventually be responsible for these functional foods' nutritional properties. This combined analytical and computational framework provided a promising platform to predict the nutritional metabolome-wide outcome of functional food consumption, as in the case of microgreens.

Effect of inulin on breath hydrogen, postprandial glycemia, gut hormone release, and appetite perception in RYGB patients: a prospective, randomized, cross-over pilot study

Background and objectiveLarge intestinal fermentation of dietary fiber may control meal-related glycemia and appetite via the production of short-chain fatty acids (SCFA) and the secretion of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). We investigated whether this mechanism contributes to the efficacy of the Roux-en-Y gastric bypass (RYGB) by assessing the effect of oligofructose-enriched inulin (inulin) vs. maltodextrin (MDX) on breath hydrogen (a marker of intestinal fermentation), plasma SCFAs, gut hormones, insulin and blood glucose concentrations as well as appetite in RYGB patients.MethodEight RYGB patients were studied on two occasions before and ~8 months after surgery using a cross-over design. Each patient received 300 ml orange juice containing 25 g inulin or an equicaloric load of 15.5 g MDX after an overnight fast followed by a fixed portion snack served 3 h postprandially. Blood samples were collected over 5 h and breath hydrogen measured as well as appetite assessed using visual analog scales.ResultsSurgery increased postprandial secretion of GLP-1 and PYY (P ≤ 0.05); lowered blood glucose and plasma insulin increments (P ≤ 0.05) and reduced appetite ratings in response to both inulin and MDX. The effect of inulin on breath hydrogen was accelerated after surgery with an increase that was earlier in onset (2.5 h vs. 3 h, P ≤ 0.05), but less pronounced in magnitude. There was, however, no effect of inulin on plasma SCFAs or plasma GLP-1 and PYY after the snack at 3 h, neither before nor after surgery. Interestingly, inulin appeared to further potentiate the early-phase glucose-lowering and second-meal (3–5 h) appetite-suppressive effect of surgery with the latter showing a strong correlation with early-phase breath hydrogen concentrations.ConclusionRYGB surgery accelerates large intestinal fermentation of inulin, however, without measurable effects on plasma SCFAs or plasma GLP-1 and PYY. The glucose-lowering and appetite-suppressive effects of surgery appear to be potentiated with inulin.

The addition of polysaccharide gums to Aronia melanocarpa purees modulates the bioaccessibility of phenolic compounds and gut microbiota: A multiomics data fusion approach following in vitro digestion and fermentation

This study aimed to determine how the addition of gellan, guar, locust bean, and xanthan gums affected the polyphenol profile of Aronia melanocarpa puree and the human gut microbiota after in vitro gastrointestinal digestion and large intestine fermentation. The different gums distinctively affected the content and bioaccessibility of phenolics in Aronia puree, as outlined by untargeted metabolomics. The addition of locust bean gum increased the levels of low-molecular-weight phenolics and phenolic acids after digestion. Gellan and guar gums enhanced phenolic acids' bioaccessibility after fermentation. Interactions between digestion products and fecal bacteria altered the composition of the microbiota, with the greatest impact of xanthan. Locust bean gum promoted the accumulation of different taxa with health-promoting properties. Our findings shed light on the added-value properties of commercial gums as food additives, promoting a distinctive increase of polyphenol bioaccessibility and shifting the gut microbiota distribution, depending on their composition and structural features.

How important is food structure when cats eat mice?

Feeding whole prey to felids has shown to benefit their gastrointestinal health. Whether this effect is caused by the chemical or physical nature of whole prey is unknown. Fifteen domestic cats, as a model for strict carnivores, were either fed minced mice (MM) or whole mice (WM), to determine the effect of food structure on digestibility, mean urinary excretion time (MUET) of 15N, intestinal microbial activity and fermentation products. Faeces samples were collected after feeding all cats a commercially available extruded diet (EXT) for 10 d before feeding for 19 d the MM and WM diets with faeces and urine collected from day 11 to 15. Samples for microbiota composition and determination of MUET were obtained from day 16 to 19. The physical structure of the mice diet (minced or not) did not affect large intestinal fermentation as total SCFA and branched-chain fatty acid (BCFA), and most biogenic amine (BA) concentrations were not different (P > 0·10). When changing from EXT to the mice diets, the microbial community composition shifted from a carbolytic (Prevotellaceae) to proteolytic (Fusobacteriaceae) profile and led to a reduced faecal acetic to propionic acid ratio, SCFA, total BCFA (P < 0·001), NH3 (P = 0·04), total BA (P < 0·001) and para-cresol (P = 0·08). The results of this study indicate that food structure within a whole-prey diet is less important than the overall diet type, with major shifts in microbiome and decrease in potentially harmful fermentation products when diet changes from extruded to mice. This urges for careful consideration of the consequences of prey-based diets for gut health in cats.

Endogenous mucin conveyed to the mucosa with microbes can assure lumen fermentation and large intestinal security-swine versus fowl.

Endogenous protein leaving the ileum largely consists of accrued mucins from the upper gastrointestinal tract (GIT) that had resisted digestion. The amounts released rely on their mucosal generation during enteral feeding which vary with age as well as diet. These digestion resistant proteins of endogenous origin continue to be unavailable in the large intestine, whereas those of dietary origin provide amino acids that largely support the existing microbial population while denying limited amounts for absorption. Other mucins pre-exist within the large intestine as two layers at the lumen surface. A loose layer harboring a diverse microbial population is superimposed on the unstirred water layer (USWL) which simultaneously acts as an obstacle to microbes at the loose layer while performing as a molecular sieve for nutrients. The USWL is formed through interplay between enterocyte and goblet cells; however, the basis for presence of the loose layer is elusive. Large intestinal fermentation predominates within the colon of swine, whereas fowl employ their ceca. Motility within the colon of swine segregates fine materials into haustrae out-pocketings that parallel their placement within the ceca of fowl. Viscous mucins from small intestinal endogenous losses may envelop microbes within the large intestinal lumen to present successive adherents on the USWL that assemble its loose layer. The loose layer continually functions as a microbial reservoir in support of lumen fermentation. Microbial catabolism of mucin within the loose layer is known to be slow, but its proximity to the enterocyte is of advantage to enterocyte absorption with by-product amino acids fostering the USWL.

Pectin conformation influences the bioaccessibility of cherry laurel polyphenols and gut microbiota distribution following in vitro gastrointestinal digestion and fermentation

Interactions between dietary fiber and phenolic compounds in foods can influence their gastrointestinal fate. This study aimed to examine the effect of four types of pectin on the polyphenols of cherry laurel puree and human gut microbiota during a simulated in vitro gastrointestinal digestion and large intestine fermentation. Results revealed that the combined addition of different pectins and pectinase to cherry laurel puree significantly affected the content and bioaccessibility of phenolics. The addition of pectins and pectinase distinctively impacted the phenolic subclasses in both raw and post-digested/fermented cherry laurel puree, suggesting differential interactions due to structural features. Both pectins and pectinase modulated the composition of fecal microbiota after in vitro fermentation, increasing bacterial diversity following pectinase treatment. The combined addition of pectins followed by pectinase had differential impacts on polyphenol bioaccessibility and gut microbiome diversity, hence having a potential outcome in terms of human health.

The functional implications of high-amylose wholegrain wheat flours: An in vitro digestion and fermentation approach combined with metabolomics.

Wheat flour is one of the most prevalent foodstuffs for human consumption, and novel strategies are underway to enhance its nutritional properties. This work evaluated wholegrain flours from bread wheat lines with different amylose/amylopectin ratios through in vitro starch digestion and large intestine fermentation. High-amylose flours presented a higher resistant starch content and lower starch hydrolysis index. Moreover, UHPLC-HRMS metabolomics was carried out to determine the profile of the resulting in vitro fermentates. The multivariate analysis highlighted distinctive profiles between the flours derived from the different lines compared to the wild type. Peptides, glycerophospholipids, polyphenols, and terpenoids were identified as the main markers of the discrimination. The high-amylose flour fermentates showed the richest bioactive profile, containing stilbenes, carotenoids, and saponins. Present findings pave the way toward applying high-amylose flours to design novel functional foods.

Enzymatic arabinose depletion of wheat arabinoxylan regulates in vitro fermentation profiles and potential microbial degraders

Arabinoxylan (AX) is a major dietary fibre in wheat/rye consisting of a xylan backbone with one or two single arabinose units attached to selected backbone xylose units. Whether these substitution patterns affect AX-degrading gut microbes, and to what extent, is incompletely understood. Herein an in vitro fermentation study is reported where a porcine faecal inoculum (as a model for human large intestine fermentation) was used to investigate the fermentability of wheat AX before and after hydrolysis by enzymes that selectively hydrolyse mono- or di-substituted arabinose residues, or both. Results showed that lower arabinose-to-xylose (A:X) ratios and lower di-substitution levels contributed to slower substrate disappearance, but higher microbial diversity evenness (alpha diversity). AX structure also affected microbial beta diversity, where genera regarded as potential AX degraders differed between the enzymatically-modified AX samples. Interestingly, higher Prevotella relative abundance was associated with higher A:X ratios and faster substrate fermentability, while higher relative abundances of Lachnospiraceae XPB1014 group, Lachnospiraceae MK4A136 group and Lachnospiraceae UCG-009 were linked to more slowly fermentable AX. Gas kinetics and end-product analyses revealed: i) gas production rates but not total gas production depended on both the A:X ratio and substitution patterns; ii) faster fermentation rates led to higher propionate proportions but lower acetate and butyrate proportions; iii) ammonia concentration resulting from different substrates reflected fermentation kinetics. Correlation analyses revealed the potential link between microbial AX degraders and fermentation outcomes specific to AX fine structures. Overall, this study reveals that gut microbial composition and fermentation outcomes can be altered by modifying the fine structure of arabinoxylan.

The impact of metallic nanoparticles on gut fermentation processes: An integrated metabolomics and metagenomics approach following an in vitro digestion and fecal fermentation model

Metallic nanoparticles (MNPs) are becoming widespread environmental contaminants. They are currently added to several food preparations and cause a fast-growing concern for human health. The present work aims to assess the impact of zinc oxide (ZnO), titanium dioxide (TiO2), and silver (Ag) nanoparticles (NPs) on the human gut metabolome and microbiome. Water samples spiked with two different concentrations of each MNPs were subjected to in-vitro gastrointestinal digestion and in-vitro large intestine fermentation. The effects of the treatments were determined through 16 S amplicon sequencing and untargeted metabolomics. Multi-omics data integration was then applied to correlate the two datasets. MNPs treatments modulated the microbial genera Bifidobacterium, Sutterella, Escherichia and Bacteroides. The treatments, especially the lower concentrations of Ag and ZnO, caused modulation of indole derivatives, peptides, and metabolites related to protein metabolism in the large intestine. Notably, these metabolites are implicated in ulcerative colitis and inflammatory bowel disease. TiO2 NPs treatment in all concentrations increased E.coli relative abundance and decreased the abundance of B. longum. Moreover, for TiO2, an enrichment in proinflammatory lipid mediators of arachidonic acid metabolites, such as prostaglandin E2 and leukotrienes B4, was detected. For all metals except TiO2, low NP concentrations promoted differentiated profiles, thus suggesting that MNPs aggregation can limit adverse effects on living cells.

The Effect of Supplementation with Betaine and Zinc on In Vitro Large Intestinal Fermentation in Iberian Pigs under Heat Stress

We investigated the effects of betaine and zinc on the in vitro fermentation of pigs under heat stress (HS). Twenty-four Iberian pigs (43.4 ± 1.2 kg) under HS (30 °C) were assigned to treatments for 4 weeks: control (unsupplemented), betaine (5 g/kg), and zinc (0.120 g/kg) supplemented diet. Rectal content was used as the inoculum in 24-hincubations with pure substrates (starch, pectin, inulin, cellulose). Total gas, short-chain fatty acid (SCFA), and methane production and ammonia concentration were measured. The abundance of total bacteria and several bacterial groups was assessed. Betaine increased the acetate production with pectin and inulin, butyrate production with starch and inulin, and ammonia concentration, and decreased propionate production with pectin and inulin. The abundance of Bifidobacterium and two groups of Clostridium decreased with betaine supplementation. Zinc decreased the production of SCFA and gas with starch and inulin, associated with diminished bacterial activity. Propionate production decreased with starch, pectin, and inulin while butyrate production increased with inulin, and isoacid production increased with cellulose and inulin in pigs supplemented with zinc. The ammonia concentration increased for all substrates. The Clostridium cluster XIV abundance decreased in pigs fed zinc supplemented diets. The results reported were dependent on the substrate fermented, but the augmented butyrate production with both betaine and zinc could be of benefit for the host.

Sorghum tannin extract impedes in vitro digestibility and fermentability of nutrients in the simulated porcine gastrointestinal tract.

The site and extent of digestion of sorghum nutrients affected by tannins in the intestine are not clarified. Porcine small intestine digestion and large intestine fermentation were simulated in vitro to determine the effects of sorghum tannin extract on the digestion and fermentation characteristics of nutrients in the mimicked porcine gastrointestinal tract. In experiment 1, low-tannin sorghum grain without or with 30 mg/g sorghum tannin extract were digested by porcine pepsin and pancreatin to measure in vitro digestibility of nutrients. In experiment 2, the lyophilized porcine ileal digesta from 3 barrows (Duroc × Landrace × Yorkshire, 27.75 ± 1.46 kg) fed the low-tannin sorghum grain without or with 30 mg/g sorghum tannin extract and the undigested residues from experiment 1 were, individually, incubated with fresh pig cecal digesta as inoculums for 48 h to simulate the porcine hindgut fermentation. The results revealed that sorghum tannin extract decreased in vitro digestibility of nutrients both by pepsin hydrolysis or pepsin-pancreatin hydrolysis (P < 0.05). Although enzymatically unhydrolyzed residues provided more energy (P = 0.09) and nitrogen (P < 0.05) as fermentation substrates, the microbial degradation of nutrients from unhydrolyzed residues and porcine ileal digesta were both decreased by sorghum tannin extract (P < 0.05). Regardless of unhydrolyzed residues or ileal digesta as fermentation substrates, microbial metabolites including the accumulative gas production excluding the first 6 h, total short-chain fatty acid and microbial protein content in the fermented solutions were decreased (P < 0.05). The relative abundances of Lachnospiraceae AC2044 and NK4A136 and Ruminococcus_1 was decreased by sorghum tannin extract (P < 0.05). In conclusion, sorghum tannin extract not only directly decreased the chemical enzymatic digestion of nutrients in the simulated anterior intestine, but also directly inhibited the microbial fermentation including microbial diversities and metabolites in the simulated posterior intestine of pigs. The experiment implies that the decreased abundances of Lachnospiraceae and Ruminococcaceae by tannins in the hindgut may weaken the fermentation capacity of microflora and thus impair the nutrient digestion in the hindgut, and ultimately reduce the total tract digestibility of nutrients in pigs fed high tannin sorghum.

Comparative digestion and fermentation characteristics of low-tannin or high-tannin sorghum grain in the porcine gastrointestinal tract.

High-tannin sorghum grain (HTS) has been previously proved to contain lower apparent total tract digestibility (ATTD) of nutrients than low-tannin sorghum grain (LTS) for pigs. This study was conducted to identify in which segments (foregut or hindgut) of the intestinal tract of pigs the digestion of nutrients was mostly influenced, and to compare the digestion and fermentation characteristics of LTS and HTS in the porcine gastrointestinal tract. In experiment 1, HTS and LTS were digested by porcine pepsin and pancreatin to simulate small intestine digestion, and subsequently the undigested residues were incubated with fresh pig cecal digesta as inoculums for 48 h to simulate the porcine large intestine fermentation in vitro. The results revealed that the in vitro digestibility of air-dry matter, gross energy (GE), and crude protein (CP) was lower (P < 0.05) in HTS than that in LTS, regardless of the simulated small intestine digestion or large intestine fermentation. The enzymatically unhydrolyzed residue of HTS decreased the accumulative gas production excluding the first 3 h and the short-chain fatty acid concentration including acetic acid, propionic acid, and butyric acid in the fermented solutions (P < 0.05), although it provided more nutrients as fermentation substrates (P < 0.05). In experiment 2, 12 crossbred barrows (25.5 ± 2.5 kg body weight) with a T-cannula inserted in the distal ileum were randomly allotted to two diets (N = 6) to determine nutrient digestibility in the foregut (AID, apparent ileal digestibility) and in the hindgut of pigs (HGD, hindgut disappearance). The study lasted 10 d, with a 5 d adaption to the diets followed by a 3 d collection of feces and then a 2 d collection of ileal digesta. Diets included 96.6% HTS or LTS as the only source of dietary energy and nitrogen. The AID and ATTD of dry matter, GE, and CP in HTS were lower than those in LTS (P < 0.05). There was no difference in HGD of nutrients between LTS and HTS. Eight out of fifteen amino acids in HTS had lower AID values (P < 0.05). In conclusion, HTS provided lower small intestine digestibility of nutrients and lower large intestine fermentation parameters, implying that condensed tannins in sorghum grain may impede the nutrient digestibility in the foregut and limit the fermentability in the hindgut segment of pigs. Hence, digestion and fermentation characteristics of sorghum grain may vary depending on the condensed tannins.

Combination of fiber-degrading enzymatic hydrolysis and lactobacilli fermentation enhances utilization of fiber and protein in rapeseed meal as revealed in simulated pig digestion and fermentation in vitro

As the increased rapeseed meal (RSM) production in last decades, improving the utilization of RSM is considered a major target in agricultural biotechnology. A series of in vitro studies were conducted to determine the effects of fiber-degrading enzymes and lactobacilli fermentation on the nutritional value of RSM. In experiment 1, the mixture of three strains of lactobacillus (L. reuteri L45, L. plantarum L47, and L. johnsonii L63) were applied to ferment RSM for 48 h after fiber-degrading enzymatic hydrolysis (a mixture of 10 FPU/g cellulase and 10 U/g pectinase) for 28 h. Four treatment groups were assigned: i) RSM without lactobacilli and enzymes (CON); ii) RSM with lactobacilli (LA); iii) RSM with enzymes (EN); and iv) RSM with enzymes and lactobacilli (EN + LA). Each group had 4 replicates. Lactobacilli growth characteristics were detected after the experiment. All RSM samples were dried and used for experiment 2. In experiment 2, samples of 4 groups were digested by pepsin and pancreatin to simulated small intestine digestion. Digestibility of dry matter and crude protein (CP) in vitro was measured. In experiment 3, undigested residues from each group were incubated with fresh pig rectum digesta as inoculums for 48 h to simulated the porcine large intestine fermentation in vitro. Accumulative gas production was recorded and modeled to estimate kinetics of gas production. Short-chain fatty acid (SCFA) concentration was measured at the end of fermentation. In experiment 1, the results demonstrated that reducing sugar concentration in EN was higher than that in CON. Compared with LA, lactic acid concentration and count of viable Lactobacillus were higher, and pH was lower in EN + LA. Rapeseed meal treated with EN + LA presented the lowest value of glucosinolate and the highest value of CP as well. In experiment 2, in vitro dry matter and CP digestibility of RSM was increased by 23 % and 20 %, respectively, by the addition of EN regardless of LA addition through a simulated small intestine digestion in vitro. The findings in experiment 3 showed that EN + LA reduced the accumulative gas production and SCFA compared with CON, indicating an improvement in utilization of carbohydrates and protein in both enzymatic hydrolysis and lactobacilli fermentation and in vitro digestion. Overall, fiber-degrading enzymes promoted the growth of lactobacilli on RSM, and the combination of fiber-degrading enzymatic hydrolysis and lactobacilli fermentation enhanced nutritional value and utilization of fiber and protein in RSM.

Pretreatment of Rapeseed Meal Increases Its Recalcitrant Fiber Fermentation and Alters the Microbial Community in an in vitro Model of Swine Large Intestine.

The aim of current study was to investigate in an in vitro study how enzymatic and chemical pretreated rapeseed meal (RSM) influences the fiber fermentation and microbial community in the swine large intestine. RSM was processed enzymatically by a cellulase (CELL), two pectinases (PECT), or chemically by an alkaline (ALK) treatment. 16S rRNA gene sequencing data was performed to evaluate changes in the gut microbiota composition, whereas short-chain fatty acid (SCFA) production (ion-chromatography) and non-starch polysaccharides (NSP) composition (using monoclonal antibodies; mAbs) were used to assess fiber degradation. The results showed that ALK, CELL, PECT1, and PECT2 changed microbial community composition, increased the predicted abundance of microbial fiber-degrading enzymes and pathways, and increased acetic acid, propionic acid, butyric acid, and total SCFA production. The increased microbial genera positively correlated with SCFA production. Monoclonal antibody analyses showed that the cell wall polysaccharide structures of RSM shifted after ALK, CELL, PECT1, and PECT2 treatment. The degradation of NSP during the fermentation period was dynamic, and not continuous based on the epitope recognition by mAbs. This study provides the first detailed analysis of changes in the swine intestinal microbiota due to RSM modified by ALK, CELL, PECT1, and PECT2, which altered the microbial community structure, shifted the predicted functional metagenomic profile and subsequently increased total SCFA production. Our findings that ALK, CELL, PECT1, and PECT2 increased fiber degradability in RSM could help guide feed additive strategies to improve efficiency and productivity in swine industry. The current study gave insight into how enzymatic treatment of feed can alter microbial communities, which provides good opportunity to develop novel carbohydrase treatments, particularly in swine feed.

Polyphenols and Sesquiterpene Lactones from Artichoke Heads: Modulation of Starch Digestion, Gut Bioaccessibility, and Bioavailability following In Vitro Digestion and Large Intestine Fermentation.

Artichoke is a relevant source of health-promoting compounds such as polyphenols and sesquiterpene lactones. In this study, the bioaccessibility and gut bioavailability of artichoke constituents were evaluated by combining in vitro digestion and large intestine fermentation, metabolomics, and Caco-2 human intestinal cells model. Moreover, the ability of artichoke polyphenols to modulate the in vitro starch digestibility was also explored. An untargeted metabolomic approach based on liquid chromatography quadrupole-time-of-flight (UHPLC/QTOF) mass spectrometry coupled with multivariate statistics was used to comprehensively screen the phytochemical composition of raw, digested, and fermented artichoke. Overall, a large abundance of phenolic acids and sesquiterpene lactones was detected, being 13.77 and 11.99 mg·g−1, respectively. After 20 h of in vitro large intestine fermentation, a decrease in polyphenols and sesquiterpene lactones content was observed. The most abundant compounds characterizing the raw material (i.e., chlorogenic acid and cynaropicrin equivalents) showed an average % bioaccessibility of 1.6%. The highest % bioaccessibility values were recorded for flavonoids such as anthocyanin and flavone equivalents (on average, 13.6%). However, the relatively high bioavailability values recorded for flavonols, phenolic acids, and sesquiterpene lactones (from 71.6% up to 82.4%) demonstrated that these compounds are able to be transported through the Caco-2 monolayer. The phenolic compounds having the highest permeation rates through the Caco-2 model included low molecular weight phenolics such as tyrosol and 4-ethylcatechol; the isoflavonoids 3′-O-methylviolanone, equol 4′-O-glucuronide, and hydroxyisoflavone; together with the methyl and acetyl derivatives of glycosylated anthocyanins. Therefore, although human in vivo confirmatory trials are deemed possible, current findings provide insights into the mechanistic effects underlying artichoke polyphenols and sesquiterpenoids bioavailability following gastrointestinal and large intestine processes.

Effects of calcium carbonate, magnesium oxide and encapsulated sodium bicarbonate on measures of post-ruminal fermentation.

Evidence suggests that lipopolysaccharide (LPS) absorbed from the large intestine may contribute to the inflammatory response to high starch feeding in dairy cows. This work evaluated the impact of buffers or alkalinizing agents with expected large intestinal activity on faecal indicators of intestinal fermentation and LPS. Ten late-lactation cows were used in a replicated 5×5 Latin square design with 7-day periods. Cows were fed a diet containing 265g/kg dry matter of starch and were abomasally infused with 1g/kg body weight cornstarch daily. Treatments were control (CON), ration supplementation with 200g/day sodium bicarbonate (FSB), 200g/day calcium carbonate (FCC) or 125g/day calcium carbonate plus 75g/day of magnesium oxide (FCCM), or abomasal infusion of a lipid encapsulate providing 200g/day sodium bicarbonate (ISB). The FCC, FCCM and ISB treatments were hypothesized to have large intestinal buffering effects, and FSB was included as a secondary control. Milk, feed, rumen and faecal samples were collected on day 7 of each period. Treatment did not affect intake, milk yield or milk composition. There were no effects of treatment on ruminal measures except that ISB tended to reduce and the post-ruminal treatments as a whole (FCC, FCCM and ISB) reduced rumen butyrate compared with CON. Faecal pH was greater for FCCM compared with all other treatments. Total faecal VFA tended to increase with FCC and FCCM compared with CON and was increased by the post-ruminal treatments as a whole compared with CON. Treatment did not affect faecal dry matter, lactate or LPS or apparent total tract nutrient digestibility. Although some treatments altered fermentation as evidenced by the change in faecal VFA, this was not accompanied by a decrease in faecal LPS. The strategies employed in this study had limited effects on large intestinal fermentation.

Effect of different soluble dietary fibres on the phenolic profile of blackberry puree subjected to in vitro gastrointestinal digestion and large intestine fermentation.

The aim of this study was to investigate the modulation of polyphenols profile of blackberry purees by soluble dietary fibres (inulin or pectin), during a simulated in vitro gastrointestinal digestion and large intestine fermentation process. Untargeted profiling evidenced that the free phenolic fraction of blackberry puree was characterized mainly by flavonoids, followed by phenolic acids, lignans and other low molecular weight polyphenols, showing clear differences from the bound phenolic fraction detected. This trend could be related to the interactions of dietary fibre and polyphenols, showing synergistic and/or antagonist effect on the bioactivity of polyphenols. On the other hand, in vitro large intestine fermentation of blackberry purees following in vitro gastrointestinal digestion revealed that the highest inclusion level (10% w/w) of soluble dietary fibres was effective in modulating the bioaccessibility of some phenolic classes (mainly phenolic acids, lignans and flavones) characterizing the blackberry puree. In addition, multivariate statistics following metabolomics-based profiling showed that the interaction between fibres and blackberry purees determined a marked modification of both anthocyanins and flavonols during in vitro large intestine fermentation, thus leading to the formation of low-molecular-weight compounds (such as tyrosol, followed by gallic and benzoic acids).

Structure characterization of soluble dietary fiber fractions from mushroom Lentinula edodes (Berk.) Pegler and the effects on fermentation and human gut microbiota in vitro.

Aimed to evaluate the changes of three soluble dietary fibers from Lentinula edodes by-products (LESDF) with different molecular weights in the digestive system and their effects on large intestinal fermentation, fermentation products and the types of gut microbiota were determined. The 1D/2D NMR results showed that main form of glucose in LESDF-1 was methyl glycopyranosides and LESDF-3 had distinct branching structures in possible repetitive unit. LESDF-2 showed the beneficial fermentation performance with the slower changes of total carbohydrate consumption and highest production of propionic acid and butyric acid. Results suggested that branched chain structure could increase the consumption rate of LESDF, but not affect the concentration of total SCFAs produced. LESDF-3 was found to promote the production of Bacteroides, which indicated LESDF was one of the nutritional components with the influence on the composition and relative abundance of intestinal microbial community.

PSIII-41 Fecal characteristics and metabolite concentrations of cats fed a high-protein, high-fiber diet after spay surgery

Abstract Dietary fiber and protein concentrations can impact large intestinal fermentation and metabolite concentrations, consequently affecting gastrointestinal health and fecal characteristics. The objective of this study was to evaluate the effects of dietary intervention on fecal characteristics and metabolite concentrations of cats after spay surgery. Twenty healthy female cats (mean age=9.5±0.1 months) were used in a 29-wk longitudinal study. After a 5-wk baseline phase being fed a moderate-protein, moderate-fiber (MPMF) diet, sixteen cats were spayed and randomly allotted to the MPMF diet (n = 8) or a high-protein, high-fiber (HPHF) diet (n = 8) and fed for 24wk. Remaining cats (n = 4) were sham-operated and fed the MPMF diet. Cats were fed to maintain BW the first 12wk, then fed up to twice that amount for another 12wk to measure changes in fecal characteristics and metabolite concentrations when allowed to overeat. Fresh fecal samples were collected before surgery (wk0) and 2, 4, 6, 12, 18, and 24wk after surgery for fecal score, pH and metabolite measurements. Fecal pH was higher (P &amp;lt; 0.01) in HPHF cats than MPMF and sham cats. Sham cats generally had greater (P &amp;lt; 0.05) fecal total SCFA, acetate, butyrate, total BCFA and phenol concentrations than HPHF cats. HPHF cats also had lower (P &amp;lt; 0.01) fecal valerate, but higher (P &amp;lt; 0.01) fecal indole concentrations than MPMF and sham cats. Significant time effects (P &amp;lt; 0.01) were observed for fecal score, pH, acetate, butyrate, propionate, total SCFA, isobutyrate, isovalerate, valerate, total BCFA, 4-ethylphenol, indole, total indole and phenols, and ammonia. Some treatment*time effects (P &amp;lt; 0.05) were observed for fecal pH, isovalerate, ammonia, butyrate, valerate, BCFA, and indole. Our results suggest that dietary protein and fiber concentrations affect the fecal characteristics and metabolite profiles of cats. Future studies should evaluate the microbiota affected to determine which groups are responsible and what these changes mean to feline health.

Untargeted metabolomics reveals changes in phenolic profile following in vitro large intestine fermentation of non-edible parts of Punica granatum L.

In this study, the untargeted phytochemical profile of non-edible parts of pomegranate (i.e., flowers, leaves and peels) was depicted by using untargeted metabolomics. Each sample was in vitro digested and then fermented simulating a large intestinal process, then monitoring the changes of phenolic bioaccessibility. The most abundant compounds in pomegranate extracts were polyphenols, terpenoids, sterols, alkaloids and amino acids. The untargeted metabolomic approach revealed a transformation of flavonoids over 24h of in vitro fermentation. In particular, an increase in the % bioaccessibility for phenolic acids and tyrosols in flowers (probably due to the insoluble dietary fibre content, i.e., 27.1g 100g-1) was observed. Accordingly, the highest % bioaccessibility was detected after 24h of in vitro large intestine fermentation for flower (i.e., 53.8%). Results showed that non-edible parts of pomegranate could be used as ingredients for the development of potential value-added food and industrial products.