Differential effects of pectin-based dietary fibre type and gut microbiota composition on in vitro fermentation outcomes.

Interactions between human gut microbiota and dietary fibres (DF) are influenced by the complexity and diversity of both individual microbiota and sources of DF. Based on 480 in vitro fermentations, a full factorial experiment was performed with six faecal inocula representing two enterotypes and three DF sources with nanometer, micrometer, and millimeter length-scales (apple pectin, apple cell walls and apple particles) at two concentrations. Increasing DF size reduced substrate disappearance and fermentation rates but not biomass growth.

Biomass attachment and microbiota shifts during porcine faecal fermentation of almond and macadamia nuts differing in particle sizes.

Nuts are highly nutritious and good sources of dietary fibre, when consumed as part of a healthy human diet. Upon consumption, nut particles of various sizes containing lipids entrapped by the plant cell walls enter the large intestine where they are fermented by the resident microbiota. This study investigated the microbial community shifts during fermentation of almond and macadamia substrates, of two particle sizes including fine particles (F = 250-500 μm) and cell clusters (CC = 710-1000 μm).

Bringing back a forgotten legume-Sensory profiles of Australian native wattleseeds reveal potential for novel food applications.

Documented as one of the oldest living civilizations, there is now evidence that Indigenous communities in Australia followed a sustainable lifestyle with well-designed agricultural practices and adequate physical activity. Commonly known as wattleseeds in Australia, unique cultivars of Acacia have been consumed by Indigenous Australians for over 60,000 years. This research used descriptive sensory profiling to develop a lexicon for the aroma and flavor profiles of four wattleseed species before and after being subjected to different processing techniques.

Novel constituents of L. (chia) nutlet mucilage and the improved fermentation of nutlets when ground.

Upon wetting, chia ( L.) nutlets produce a gel-like capsule of polysaccharides called mucilage that comprises a significant part of their dietary fibre content. Seed/nutlet mucilage is often used as a texture modifying hydrocolloid and bulking dietary fibre due to its water-binding ability, though the utility of mucilage from different sources is highly structure-function dependent.

fermentation profiles of undigested fractions from legume and nut particles are affected by particle cohesion and entrapped macronutrients.

Insoluble undigested food residues are the predominant dietary form of 'fibre' from food plants, with the potential for fermentation by microbial species resident within the large intestine. Here we present results on fermentation of undigested fractions of legumes (chickpea flour, lentil flour, mung bean flour), and nuts (peanut, almond, macadamia) using a pooled faecal inoculum from pigs fed a nut- and legume-free diet. All substrates were pre-digested .

Case report of a pancreatic insulinoma misdiagnosed as epilepsy.

A 55-year-old patient had spent 12 years with unexplained seizures, initially diagnosed as epilepsy and then as a psychiatric disorder. When she was admitted with hypoglycaemia, a fasting test was performed showing blood sugar levels as low as 1 mmol/L with symptoms of neuroglycopenia. Insulinoma was suspected and an MRI showed a large tumour in the tail region of the pancreas.

Interplay between grain digestion and fibre in relation to gastro-small-intestinal passage rate and feed intake in pigs.

Purpose: The combined effects of grain digestibility and dietary fibre on digesta passage rate and satiety in humans are poorly understood. Satiety can be increased through gastric distention, reduced gastric emptying rate and when partially digested nutrients reach the terminal ileum to stimulate peptide release through the ileal/colonic brakes to slow the rate of digesta passage. This study determined the effects of grain digestibility and insoluble fibre on mean retention time (MRT) of digesta from mouth-to-ileum, feed intake (FI), starch digestion to the terminal ileum and faecal short chain fatty acids (SCFA) in a pig model.

An Illustrative Analysis of Atypical Gas Production Profiles Obtained from In Vitro Digestibility Studies Using Fecal Inoculum.

Gas production profiles typically show a monotonically increasing monophasic pattern. However, atypical gas production profiles exist whereby at least two consecutive phases of gas production or additional extraneous features that distort the typical profile are present. Such profiles are more likely to occur with the use of a fecal inoculum and are much less well described.

Interaction of cellulose and xyloglucan influences in vitro fermentation outcomes.

To investigate the effects of interactions between cellulose and xyloglucan (XG) on in vitro fermentation, a composite of bacterial cellulose (BC) incorporating XG during pellicle formation (BCXG), was fermented using a human faecal inoculum, and compared with BC, XG and a mixture (BC&XG) physically blended to have the same BC to XG ratio of BCXG. Compared to individual polysaccharides, the fermentation extent of BC and fermentation rate of XG were promoted in BC&XG. XG embedded in the BCXG composite was degraded less than in BC&XG, while more cellulose in BCXG was fermented than in BC&XG.

Wheat cell walls and constituent polysaccharides induce similar microbiota profiles upon fermentation despite different short chain fatty acid end-product levels.

Plant cell walls as well as their component polysaccharides in foods can be utilized to alter and maintain a beneficial human gut microbiota, but it is not known whether the architecture of the cell wall influences the gut microbiota population. In this study, wheat flour cell walls (WCW) were isolated and compared with their major constituents - arabinoxylan (AX), mixed linkage (1,3)(1,4)-β-glucan (MLG) and cellulose - both separately and as a physical mixture of polysaccharides (Mix) equivalent in composition to WCW. These samples underwent in vitro fermentation with a faecal inoculum from pigs fed a diet free of cereals and soluble-fibre to avoid prior adaptation to substrates.

Metabolism of Black Carrot Polyphenols during In Vitro Fermentation is Not Affected by Cellulose or Cell Wall Association.

Fruit and vegetable polyphenols are associated with health benefits, and those not absorbed could be fermented by the gastro-intestinal tract microbiota. Many fermentation studies focus on "pure" polyphenols, rather than those associated with plant cell walls (PCW). Black carrots (BlkC), are an ideal model plant food as their polyphenols bind to PCW with minimal release after gastro-intestinal digestion.

fermentation outcomes of arabinoxylan and galactoxyloglucan depend on fecal inoculum more than substrate chemistry.

Using in vitro fermentation conditions, this study investigated the fermentation characteristics of arabinoxylan (AX) and xyloglucan (XG) with a fecal inoculum that was collected either from humans consuming unrestricted diets or pigs fed a semi-defined diet with cellulose being the sole non-starch polysaccharide for 10 days prior to fecal collection. Metagenomic analysis revealed that microbial communities in the two types of inoculum were distinctively different, which led to distinct fermentation characteristics with the polysaccharides. The microbial communities fermented with the porcine fecal inoculum were clustered according to the fermentation time, while those fermented with the human fecal inoculum were differentiated by the substrates.

High amylose wheat starch structures display unique fermentability characteristics, microbial community shifts and enzyme degradation profiles.

A slower rate of starch digestion in the small intestine increases the amount of resistant starch (RS) entering the large intestine, which is associated with health benefits. Although increasing the amylose (AM) content of dietary starch intake is one way to increase RS, the processes involved in gut microbial hydrolysis and fermentation of high AM-RS substrates are poorly understood. In this study, five high AM wheat (HAW) starches ranging from 47% AM to 93% AM and a wild type (37% AM), in both native granular and cooked forms, were subjected to in vitro fermentation with a porcine faecal inoculum.

Purified plant cell walls with adsorbed polyphenols alter porcine faecal bacterial communities during in vitro fermentation.

A substantial fraction of ingested polyphenols accumulate in the large intestine (LI), attached to undigested plant cell walls (PCW) (dietary fibre). Yet, whether these PCW-bound polyphenols alter the structure and function of the resident microbiota remains unclear. This study characterised bacterial populations during the in vitro fermentation of three standard polyphenols: ferulic acid (FER), (±)-catechin (CAT), and cyanidin-3-glucoside (CYAN), adsorbed individually or in combination to apple cell walls (ACW).

Wheat bran and oat hulls have dose-dependent effects on ad-libitum feed intake in pigs related to digesta hydration and colonic fermentation.

Undigested nutrients and fermentable fibre in the distal ileum and colon stimulate intestinal brakes, which reduce gastric-emptying and digesta-passage-rate, and subsequently limit feed/food-intake. Fibre can also stimulate passage rate potentially increasing feed intake (FI). In order to experimentally determine the relationships between these two hypothesised actions of fibre, five levels of wheat-bran (WB) or oat-hulls (OH) were added to a highly digestible starch-based diet fed to pigs ad-libitum for three weeks.

"Dietary fibre": moving beyond the "soluble/insoluble" classification for monogastric nutrition, with an emphasis on humans and pigs.

This review describes dietary fibres originating from a range of foods, particularly in relation to their plant cell walls. It explores the categorization of dietary fibres into "soluble" or "insoluble". It also emphasizes dietary fibre fermentability, in terms of describing how the gastro-intestinal tract (GIT) microbiota respond to a selection of fibres from these categories.

Extracellular depolymerisation triggers fermentation of tamarind xyloglucan and wheat arabinoxylan by a porcine faecal inoculum.

Arabinoxylan (AX) and xyloglucan (XG) are important components of primary cell walls of cereal grains and vegetables/fruits, respectively. Despite the established health benefits of these non-starch polysaccharides, the mechanisms of their utilisation by the gut microbiota are poorly understood. In this study, the mechanisms of solubilised wheat AX and tamarind XG degradation were investigated under in vitro fermentation conditions using a porcine faecal inoculum.

Food Starch Structure Impacts Gut Microbiome Composition.

Starch is a major source of energy in the human diet and is consumed in diverse forms. Resistant starch (RS) escapes small intestinal digestion and is fermented in the colon by the resident microbiota, with beneficial impacts on colonic function and host health, but the impacts of the micro- and nanoscale structure of different physical forms of food starch on the broader microbial community have not been described previously. Here, we use a porcine fermentation model to establish that starch structure dramatically impacts microbiome composition, including the key amylolytic species, and markedly alters both digestion kinetics and fermentation outcomes.

Mechanisms of utilisation of arabinoxylans by a porcine faecal inoculum: competition and co-operation.

Recent studies show that a single or small number of intestinal microbes can completely degrade complex carbohydrates. This suggests a drive towards competitive utilisation of dietary complex carbohydrates resulting in limited microbial diversity, at odds with the health benefits associated with a diverse microbiome. This study investigates the enzymatic metabolism of wheat and rye arabinoxylans (AX) using in vitro fermentation, with a porcine faecal inoculum.

Male grower pigs fed cereal soluble dietary fibres display biphasic glucose response and delayed glycaemic response after an oral glucose tolerance test.

Acute and sustained soluble dietary fibre (SDF) consumption are both associated with improved glucose tolerance in humans and animal models (e.g. porcine).

Dietary pectin and mango pulp effects on small intestinal enzyme activity levels and macronutrient digestion in grower pigs.

The effects of refined pectin and mango pulp on macronutrient digestion and small intestinal enzyme activity were studied in grower pigs. Diets based on wheat starch with and without apple pectin or dried mango fruit pulp were fed to 30 grower pigs for 21 days. Pigs were euthanized two hours postprandially, and their gastrointestinal contents recovered.

In vitro fermentation gas kinetics and end-products of soluble and insoluble cereal flour dietary fibres are similar.

Insoluble dietary fibre is often considered to be fermented slower and to a lesser extent in (models for) the colon than soluble dietary fibre. However these comparisons are typically made for fibre components of different composition. In the case of fibre from refined cereal flours, there is little difference in fibre composition between soluble and insoluble forms, so effects of solubility on fermentation can be tested without this confounding factor.

Gut Fermentation of Dietary Fibres: Physico-Chemistry of Plant Cell Walls and Implications for Health.

The majority of dietary fibre (DF) originates from plant cell walls. Chemically, DF mostly comprise carbohydrate polymers, which resist hydrolysis by digestive enzymes in the mammalian small intestine, but can be fermented by large intestinal bacteria. One of the main benefits of DF relate to its fermentability, which affects microbial diversity and function within the gastro-intestinal tract (GIT), as well as the by-products of the fermentation process.

An updated method for the jugular catheterization of grower pigs for repeated blood sampling following an oral glucose tolerance test.

Jugular catheterization is a common procedure used under experimental conditions. However, there is considerable variation in the reported techniques, particularly for grower pigs (>40 kg and <60 kg) when larger volumes of blood per sample (>10 mL) are required. This paper provides a complete methodology including the use of current equipment and anaesthetic regimen for grower pigs.

Optimizing Prednisolone Loading into Distiller's Dried Grain Kafirin Microparticles, and In vitro Release for Oral Delivery.

Kafirin microparticles have potential as colon-targeted delivery systems because of their ability to protect encapsulated material from digestive processes of the upper gastrointestinal tract (GIT). The aim was to optimize prednisolone loading into kafirin microparticles, and investigate their potential as an oral delivery system. Response surface methodology (RSM) was used to predict the optimal formulation of prednisolone loaded microparticles.