High Molecular Weight Β-glucan Research Articles

Filtration enzymes applied during mashing affect beer composition and viscosity

Why was the work done: Filtration enzymes that target the degradation of arabinoxylan and β-glucan are widely used in the brewing industry to improve wort and beer filtration. Although these enzymes have proven their effectiveness in improved lautering efficiency and beer filterability, the effect of varying dosage and type of enzyme preparations on beer composition and quality has not been described.
 How was the work done: The impact of dosage of different filtration enzyme preparations (Laminex®750, Laminex®C2K, and Laminex®MaxFlow4G) was investigated on the free ferulic acid content in the wort, chemical composition and viscosity of beer, together with an emphasis on the content and structure of arabinoxylan and β-glucan.
 What are the main findings: The structural features of arabinoxylan and β-glucan in beer were strongly influenced by the dosage and type of filtration enzyme. In general, the high-molecular weight (HMW) arabinoxylan and HMW β-glucan content, and total β-glucan content in beers decreased with increasing enzyme dosage, while the total arabinoxylan levels increased. The HMW arabinoxylan content was strongly related to beer viscosity. The use of filtration enzymes led to a decreased HMW arabinoxylan content and decreased beer viscosity, which could affect the palate fullness of beers. Overdosing filtration enzymes resulted in more ferulic acid, the precursor (in the presence of phenolic yeast) to the clove-like 4-vinyl guaiacol.
 Why is the work important: This work provides brewers with insight on how filtration enzymes affect beer composition and viscosity. It can help make an informed choice of the type of filtration enzyme and the dosage applied during mashing.

FT-IR Method Limitations for β-Glucan Analysis.

β-glucans are known as biological response modifiers. However, different sources can result in structural differences and as a result differences in their biological activity. The hot water extraction method allows to obtain, high molecular weight β-glucans without altering their structure by using strong chemicals, such as alkalis or acids. Analysis of β-glucans by FT-IR and NMR spectroscopy in solid state is superior to analysis in solution as it allows researchers to study the preserved structure of the extracted polysaccharides. FT-IR spectroscopy was used in this study to make side-by-side comparison analysis of hot water extracted β-glucans from different yeast sources. NMR spectroscopy was used to confirm findings made by FT-IR spectroscopy. Extracted β-glucans exhibit characteristic structure of β-1,3/1,6-linked glucans with noticeable levels of proteins, possibly in a form of oligopeptides, chitin and other impurities. β-glucans obtained from C. guilliermondii, P. pastoris and S. pastorianus exhibited higher protein content. Differences in mannan, chitin and α-glucan content were also observed; however, the species-specific structure of obtained β-glucans could not be confirmed without additional studies. Structural analysis of high molecular weight β-glucans in solid state by FT-IR spectroscopy is difficult or limited due to band intensity changes and overlapping originating from different molecules.

Effects of diet hulless barley and beta-glucanase levels on ileal digesta soluble beta-glucan molecular weight and carbohydrate fermentation in laying hens

Exogenous β-glucanase (BGase) improves nutrient digestibility and production performance in laying hens fed barley-based diets, but the effect of enzyme and the dosage on β-glucan depolymerization and fermentation in the gastrointestinal tract is poorly understood. The objectives of the study were to determine the effects of hulless barley (HB) and BGase levels on digestive tract β-glucan depolymerization and fermentation in laying hens. A total of 108 Lohman-LSL Lite hens were housed in cages and fed 2 levels of HB (CDC Fibar; 0 and 73%) by substituting wheat in the diet and graded levels of BGase (Econase GT 200 P from ABVista; 0, 0.01 and 0.1% – 0, 20,000, and 200,000 BU/kg) in a 2 × 3 factorial arrangement. Birds were fed experimental diets for 8 weeks, starting at 35 wk of age. Digestive tract samples were collected at the end of the experiment. Statistical significance was set at P ≤ 0.05. Beta-glucan peak molecular weight was lower with the 0.1 compared to both 0 and 0.01% BGase levels, whereas weight average molecular weight was lower with the 0.1 compared to 0% BGase for 73% HB. The maximum molecular weight for the smallest 10% β-glucan molecules decreased with the increasing BGase. Overall, β-glucan molecular weight in the ileum was higher when the birds were given 73 in comparison to 0% HB diets. Total and major short chain fatty acids (SCFA) in the ileum were lower with 0.1 and 0.01 (except propionic acid) compared to 0% BGase in the birds fed 73% HB, but not 0% HB. Interactions between the main effects were found for the cecal acetic and isobutyric acids. In conclusion, exogenous BGase depolymerized high molecular weight β-glucan in HB and wheat. The effects of HB and BGase on carbohydrate fermentation were not apparent, although it appears ileal SCFA concentrations were lower with increasing levels of BGase.

Hulless barley and β-glucanase affect ileal digesta soluble beta-glucan molecular weight and digestive tract characteristics of coccidiosis-vaccinated broilers.

Exogenous β-glucanase (BGase) in barley-based feed has been shown to reduce digesta viscosity in chickens, and thereby improve performance. Less well studied is the potential for BGase to convert barley β-glucan into low molecular weight carbohydrates, which might influence digestive tract function and enteric disease. Coccidiosis-vaccinated broiler chickens were fed graded levels of hulless barley (HB) and BGase to determine their effects on β-glucan depolymerization and digestive tract characteristics. Broilers were fed high β-glucan HB (0%, 30% and 60% replacing wheat) and BGase (0%, 0.01% and 0.1%) in a 3 × 3 factorial arrangement. A total of 5,346 broilers were raised in litter floor pens and vaccinated for coccidiosis on d 5. Each treatment was assigned to 1 pen in each of 9 rooms. The significance level was set at P ≤ 0.05. At both 11 and 33 d of broiler ages, peak molecular weight of β-glucan in ileal digesta decreased with increasing BGase for 30% and 60% HB. The maximum molecular weight for the smallest 10% β-glucan molecules (MW-10%) decreased with BGase at both ages for 30% and 60% HB; for birds fed 0% HB, only 0.1% BGase decreased MW-10%. The 0.1% BGase increased caecal short chain fatty acids (SCFA) compared to the 0.01% BGase at d 11 only for the 60% HB. Ileal pH increased with increasing HB and BGase at d 11 and 33. Caecal pH was lower for 0.1% BGase than 0% BGase for 60% HB at d 11. Relative mRNA expression of interleukin 6 (IL-6) and IL-8 in the ileum increased with 0.1% BGase at d 11 and 33, respectively, whereas expression of ileal mucin 2 (MUC2) decreased with 0.1% BGase at d 33. In the caeca, interactions between HB and BGase were significant for monocarboxylate transporter 1 (MCT1) and mucin 5AC (MUC5AC) on d 11, but no treatment effects were found at d 33. In conclusion, BGase depolymerized high molecular weight β-glucan in HB in a dose-dependent manner. Hulless barley and BGase did not increase SCFA concentrations (except for 60% HB with 0.1% BGase at d 11) and caused minor effects on digestive tract histomorphological measurements and relative mRNA gene expression.

Low Molecular Weight Barley β-Glucan Affects Glucose and Lipid Metabolism by Prebiotic Effects.

We investigated the effect of low molecular weight barley β-glucan (LMW-BG) on cecal fermentation, glucose, and lipid metabolism through comparisons to high molecular weight β-glucan (HMW-BG). C57BL/6J male mice were fed a moderate-fat diet for 61 days. LMW-BG or HMW-BG was added to the diet corresponding to 4% β-glucan. We measured the apparent absorption of fat, serum biomarkers, the expression levels of genes involved in glucose and lipid metabolism in the liver and ileum, and bacterial counts of the major microbiota groups using real time PCR. The concentration of short-chain fatty acids (SCFAs) in the cecum was analyzed by GC/MS. Significant reductions in serum leptin, total- and LDL-cholesterol concentrations, and mRNA expression levels of sterol regulatory element-binding protein-1c (SREBP-1c) were observed in both BG groups. HMW-BG specific effects were observed in inhibiting fat absorption and reducing abdominal deposit fat, whereas LMW-BG specific effects were observed in increasing bacterial counts of Bifidobacterium and Bacteroides and cecal total SCFAs, acetate, and propionate. mRNA expression of neurogenin 3 was increased in the LMW-BG group. We report that LMW-BG affects glucose and lipid metabolism via a prebiotic effect, whereas the high viscosity of HMW-BG in the digestive tract is responsible for its specific effects.

Effect of oat β-glucan of different molecular weights on fecal bile acids, urine metabolites and pressure in the digestive tract – A human cross over trial

While the development of oat products often requires altered molecular weight (MW) of β-glucan, the resulting health implications are currently unclear. This 3-leg crossover trial (n = 14) investigated the effects of the consumption of oat bran with High, Medium and Low MW β-glucan (average > 1000, 524 and 82 kDa respectively) with 3 consequent meals on oat-derived phenolic compounds in urine (UHPLC-MS/MS), bile acids in feces (UHPLC-QTOF), gastrointestinal conditions (ingestible capsule), and perceived gut well-being. Urine excretion of ferulic acid was higher (p < 0.001, p < 0.001), and the fecal excretion of deoxycholic (p < 0.03, p < 0.02) and chenodeoxycholic (p < 0.06, p < 0.02) acids lower after consumption of Low MW β-glucan compared with both Medium and High MW β-glucan. Duodenal pressure was higher after consumption of High MW β-glucan compared to Medium (p < 0.041) and Low (p < 0.022) MW β-glucan. The MW of β-glucan did not affect gut well-being, but the perceptions between females and males differed.

Characterisation of the molecular properties of scleroglucan as an alternative rigid rod molecule to xanthan gum for oropharyngeal dysphagia

Scleroglucan, a neutral β(1–3) glucan with β(1–6) glucan branches every third residue, is being considered as an alternative rod-like, shear thinning high molecular weight β-glucan based polysaccharide to xanthan gum for the management of patients with oropharyngeal dysphagia. It is therefore important to understand more fully its hydrodynamic properties in solution, in particular heterogeneity, molecular weight distribution and its behaviour in the presence of mucin glycoproteins. A commercially purified scleroglucan preparation produced by fermentation of the filamentous fungus Sclerotium rolfsii was analysed in deionised distilled water with 0.02% added azide. Sedimentation velocity in the analytical ultracentrifuge showed the scleroglucan preparation to be unimodal at concentrations >0.75 mg/ml which resolved into two components at lower concentration and with partial reversibility between the components. Sedimentation coefficient versus concentration plots showed significant hydrodynamic non-ideality. Self-association behaviour was confirmed by sedimentation equilibrium experiments with molecular weights between ~3 × 106 g/mol to ~5 × 106 g/mol after correcting for thermodynamic non-ideality. SEC-MALS-viscosity experiments showed a transition between a rod-shape at lower molar masses to a more flexible structure at higher masses consistent with previous observations. Sedimentation velocity experiments also showed no evidence for potentially problematic interactions with submaxillary mucin.

Purified β-glucans of Different Molecular Weights Enhance Growth Performance of LPS-challenged Piglets via Improved Gut Barrier Function and Microbiota.

Simple SummaryBeta-glucan is currently under consideration as an alternative to in-feed antibiotics for the sustainable pig production industry in China. Modulating intestinal function by β-glucan treatment in young pigs is one potential way of decreasing disease susceptibility and presumably increasing growth performance. In the present study, as a newly developed commercial product, β-glucans have proved to modulate gut function, and have improved growth performance in lipopolysaccharide (LPS)-challenged piglets. The present study aimed to determine the mechanisms involved inβ-glucan of low and high molecular weight mediated growth alterations in weaned piglets. The results confirmed that β-glucans isolated from Agrobacterium sp. ZX09 could improve growth performance in weaned piglets and they showed intestinal modulatory properties via different mechanisms in regulating the mucosal barrier function and microbial populations between two different molecular weight β-glucans.This study investigated β-glucan derived from Agrobacterium sp. ZX09 with high (2000 kDa) and low (300 kDa) molecular weight (MW) to compare their effects on growth performance and gut function in LPS-induced weaned piglets. Changes in jejunal morphology, mucosal barrier function, microbial populations, and fermentation in the piglets were determined. Data showed that β-glucan prevented body weight loss in LPS challenged piglets. Supplementation with both β-glucan fractions improved jejunal morphology. Compared to low MW, β-glucan of high MW generally up-regulated transcripts of ZO-1, MUC1, and MUC2 in jejunal mucosa to a lesser extent. Mucosal D-lactate, diamine oxidase, and anti-oxidation index were effectively resumed in β-glucan treatment. Both β-glucan diets provoked the emergence of a balanced microbiota and a richer concentration of volatile fatty acids in the colon. The richest community of bifidobacterium and concentration of butyrate emerged after feeding β-glucan with high MW. Results suggested that the effect of Agrobacterium sp. ZX09 β-glucans on the gut-modulatory function is largely linked to their MW. Low MW β-glucan mainly improved the mucosal barrier function in the jejunum, while high MW β-glucan had profound effects on the microbial community and fermentation in the hindgut of piglets.

Effects of dietary supplementation with different levels and molecular weights of fungal β-glucan on performances, health and meat quality in broilers

ObjectiveTo investigate the effects of dietary supplementation with different levels and molecular weights of fungal β-glucan on productive performances, health, carcass traits and meat quality in broilers.MethodsTwo hundred and ten of one-day-old chicks with equal sex were assigned to seven experimental groups in 2×4 factorial arrangement. These groups were supplemented with (0, 10, 30, and 60 ppm) of molecular weight 1–3, 1–6 β-glucan (low or high). High molecular weight β-glucan (H: 943 kDa) was obtained from Ophiocordyceps dipterigena BCC 2073, whereas H with γ-Irradiation treatment was performed to achieve low molecular weight β-glucan (L: 8 kDa).ResultsThere was no statistical significance in productive performances, apparent digestibility and interaction between fixed factors along 42 days of experiment (p>0.05). A higher caecal amylase activity was present in the group that received L, while there was a dramatic decrease in H and the control groups, respectively (p<0.05). The increase of supplemental dose increased caecal amylase activity (p<0.05). Immunomodulatory effects from L was revealed by the marked increase of phagocytic activity, relative weight of thymus and bursa of fabricius (p<0.05). Similarly, the additive dose at 30 ppm provided the same results, whereas the only significant difference with supplementation at 60 ppm was an increase in phagocytic activity (p<0.05). Interestingly, villi height of broilers fed L was higher than other groups (p<0.05). The treatments did not influence haematology, blood chemistry, antibody production level against vaccination, carcass traits and meat quality (p>0.05).ConclusionThe supplementation of L at 30 ppm was suggested to achieve benefits of immune modulation without adverse effects on other parameters.

Local β-glucan source from oyster mushroom (Pleurotus flabellatus) as potential usage in medical applications

Event Abstract Back to Event Local β-glucan source from oyster mushroom (Pleurotus flabellatus) as potential usage in medical applications Shaiful A. Mohamad1*, Nur Hafizati Abd Halim1, Choong Yew Keong2, Ahmad Zainuri Mohd Dzomir1, Hafizal Yazid1, Mohd Yusof Hamzah1 and Everina Nuri1 1 Malaysian Nuclear Agency, Malaysia 2 Herbal Medicine Research Centre, Institute for Medical Research, Ministry of Health (Malaysia), Malaysia Background Many applications of mushroom polysaccharides have been reported such as in drug delivery system, skin applications and as immunomodulatory agents. The polysaccharides can be obtained from the fruit body, mycelium, culture broth and spores of mushroom. In this study, oyster mushroom (Pleurotus flabellatus) culture was produced by submerged culture fermentation due to its higher productivity and faster fermentation rate. Methods The biomass obtained from submerged culture fermentation was extracted by using hot water extraction. The polysaccharides were tested using β-glucan kit and also studied using small angle X-ray scattering (SAXS) equipment. Then the polysaccharides were separated using column chromatography before determining the molecular weight using gel permeation chromatography-multi angle laser light scattering (GPC-MALLS). Results Both endopolysaccharide and exopolysaccharide obtained have shown the presence of β-glucan (1,3;1,6). The polysaccharides also showed the presence of high molecular weight (~3×10^6 Da) and low molecular weight components. SAXS results showed that the maximum agglomerate size was ~27 nm and the average size of globular was 2.6 nm. Conclusion The presence of high molecular weight β-glucan showed potential application as immunomodulatory agents. The polysaccharides can be classified as nanobiomaterials. These studies supported potential usage of local compounds in medical applications. Keywords: Pleurotus flabellatus, Immunomodulation, Small angle X ray scattering, β-Glucan, Submerged fermentation Conference: International Conference on Drug Discovery and Translational Medicine 2018 (ICDDTM '18) “Seizing Opportunities and Addressing Challenges of Precision Medicine”, Putrajaya, Malaysia, 3 Dec - 5 Feb, 2019. Presentation Type: Poster Presentation Topic: Miscellaneous Citation: Mohamad SA, Abd Halim N, Keong C, Mohd Dzomir A, Yazid H, Hamzah M and Nuri E (2019). Local β-glucan source from oyster mushroom (Pleurotus flabellatus) as potential usage in medical applications. Front. Pharmacol. Conference Abstract: International Conference on Drug Discovery and Translational Medicine 2018 (ICDDTM '18) “Seizing Opportunities and Addressing Challenges of Precision Medicine”. doi: 10.3389/conf.fphar.2018.63.00112 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 12 Oct 2018; Published Online: 17 Jan 2019. * Correspondence: Dr. Shaiful A Mohamad, Malaysian Nuclear Agency, Kuala Lumpur, Malaysia, shaifulazuar@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Shaiful A Mohamad Nur Hafizati Abd Halim Choong Yew Keong Ahmad Zainuri Mohd Dzomir Hafizal Yazid Mohd Yusof Hamzah Everina Nuri Google Shaiful A Mohamad Nur Hafizati Abd Halim Choong Yew Keong Ahmad Zainuri Mohd Dzomir Hafizal Yazid Mohd Yusof Hamzah Everina Nuri Google Scholar Shaiful A Mohamad Nur Hafizati Abd Halim Choong Yew Keong Ahmad Zainuri Mohd Dzomir Hafizal Yazid Mohd Yusof Hamzah Everina Nuri PubMed Shaiful A Mohamad Nur Hafizati Abd Halim Choong Yew Keong Ahmad Zainuri Mohd Dzomir Hafizal Yazid Mohd Yusof Hamzah Everina Nuri Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Extraction and Isolation of β-Glucan from Grain Sources-A Review.

A collective report on the extraction and isolation of β-glucan from grain sources, namely, oat, barley, and wheat is presented. An analysis on the effect of medium, pH, and temperature on the purity and yield of the β-glucan derived under acidic/alkaline/aqueous/enzymatic conditions is also made. Water extraction and alkali extraction processes are preferred as the yield and recovery of extracted β-glucan were good. Cost-effective development of the process for deriving high molecular weight β-glucan is the current requirement for its wide applications in food and pharmaceutical industries.

Characterization of cereal β-glucan extracts from oat and barley and quantification of proteinaceous matter.

An extraction method for mixed-linkage β-glucan from oat and barley was developed in order to minimize the effect of extraction on the β-glucan structure. β-Glucan were characterized in terms of molecular size and molar mass distributions using asymmetric flow field-flow fractionation (AF4) coupled to multiangle light scattering (MALS), differential refractive index (dRI) and fluorescence (FL) detection. The carbohydrate composition of the extracts was analysed using polysaccharide analysis by carbohydrate gel electrophoresis (PACE) and high-performance anion-exchange chromatography (HPAEC). Whether there were any proteinaceous moieties linked to β-glucan was also examined. Purified extracts contained 65% and 53% β-glucan for oats and barley, respectively. The main impurities were degradation products of starch. The extracts contained high molecular weight β-glucan (105–108 g/mol) and large sizes (root-mean-square radii from 20 to 140 nm). No proteins covalently bound to β-glucan were detected; therefore, any suggested functionality of proteins regarding the health benefits of β-glucan can be discounted.

Retardation of oxidation by residual phytate in purified cereal β-glucans

Polysaccharides stabilize emulsions against phase separation and oxidation. This study focused on the role of molecule weight, origin, and residual phytate in the antioxidant activity of β-glucans. The antioxidant activity was investigated by measuring the retardation of lipid oxidation, iron binding capacity and hydroxyl radical scavenging ability of purified oat and barley β-glucans. Low molecular weight β-glucan stabilized the emulsions against phase separation and oxidation better than high molecular weight β-glucan. The oxidative stability of the emulsions, however, correlated to the content of residual phytate in the β-glucan samples. Oat β-glucans which contained higher amount of residual phytate showed higher antioxidant activity than barley β-glucans. When phytate was removed from the β-glucan samples by ion exchange, the antioxidant activity of all β-glucans was reduced to the same level. The study therefore showed that residual phytate played a major role in the antioxidant activity of cereal β-glucans. The study highlights that even at low concentration, phytate content should be considered when evaluating the antioxidant effect of plant polysaccharide extracts.

Hepato- and gastro- protective activity of purified oat 1–3, 1–4-β-d-glucans of different molecular weight

Protective and antioxidant properties of highly purified oat β-glucans of high and low molecular weight in liver and stomach were evaluated. The novelty in approach was to determine whether dietary β-glucans affect the parameters of oxidative stress directly in the stomach and indirectly in the liver, especially in inflammation states. Physicochemical properties e.g. viscoelastic was found as strictly dependent from molecular weight of oat β-glucans hence its metabolic activity could also show dependence. Three groups of rats were fed control diet and diet supplemented with low and high molecular weights oat β-glucans. Animals were divided into controls and individuals with experimentally induced intestinal inflammation. Most active in increasing of total antioxidant status was low molecular weight β-glucan. High molecular weight β-glucan supplementation inhibits lipid oxidation the most in LPS treated animals. The results obtained from experiment encourage for dietary intervention with oat β-glucans for stomach and liver protection during existing enteritis.

High-Molecular-Weight β-Glucan Decreases Serum Cholesterol Differentially Based on the CYP7A1 rs3808607 Polymorphism in Mildly Hypercholesterolemic Adults

Background: β-Glucan, a soluble fiber with viscous property, has a documented cholesterol-lowering effect. The molecular weight (MW) of β-glucan, which contributes to viscosity, and an individual's genotype might influence the cholesterol-lowering efficacy of β-glucan.Objectives: This study was designed to determine whether the cholesterol-lowering efficacy of barley β-glucan varied as a function of MW and the daily dose consumed. Our second aim was to determine whether any gene-diet interactions are associated with the cholesterol-lowering efficacy of β-glucan.Methods: In a randomized controlled crossover trial, 30 mildly hypercholesterolemic adults [12 men and 18 women, aged 27–78 y; body mass index (in kg/m2): 20–40; total cholesterol (TC): 5.0–8.0 mmol/L; LDL cholesterol: 2.7–5.0 mmol/L] were randomly assigned to receive a breakfast that contained either barley β-glucan at 3 g high MW (HMW)/d, 5 g low MW (LMW)/d, or 3 g LMW/d or a control diet, each for 5 wk. The washout period between the phases was 4 wk. Fasting blood samples were collected at the start and end of each phase for blood lipid analysis and genotyping.Results: Consumption of 3 g HMW β-glucan/d lowered TC by −0.12 mmol/L (95% CI: −0.24, −0.006 mmol/L) compared with the control diet (P = 0.0046), but the LMW β-glucan, at either 3 g/d or 5 g/d, did not change serum cholesterol concentrations. This effect of HMW β-glucan was associated with gene-diet interaction, whereby individuals with the single nucleotide polymorphism (SNP) rs3808607-G allele (GG or GT) of the cytochrome P450 family 7 subfamily A member 1 gene (CYP7A1) had greater responses to 3 g HMW β-glucan/d in lowering TC than TT carriers (P = 0.0006).Conclusions: The HMW β-glucan rather than LMW β-glucan reduced circulating TC effectively in mildly hypercholesterolemic adults. The cholesterol-lowering effect of β-glucan may also be determined by the genetic characteristics of an individual. These data show that individuals carrying the CYP7A1 SNP rs3808607-G allele are more responsive to the cholesterol-lowering effect of β-glucan with HMW than TT carriers. This trial was registered at clinicaltrials.gov as NCT01408719.

High Molecular Weight Barley β-Glucan Alters Gut Microbiota Toward Reduced Cardiovascular Disease Risk.

The physiological cholesterol-lowering benefits of β-glucan have been well documented, however, whether modulation of gut microbiota by β-glucan is associated with these physiological effects remains unknown. The objectives of this study were therefore to determine the impact of β-glucan on the composition of gut microbiota in mildly hypercholesterolemic individuals and to identify if the altered microbiota are associated with bioactivity of β-glucan in improving risk factors of cardiovascular disease (CVD). Using a randomized, controlled crossover study design, individuals received for 5-week either a treatment breakfast containing 3 g high molecular weight (HMW), 3 g low molecular weight (LMW), 5 g LMW barley β-glucan, or wheat and rice. The American Heart Association (AHA) diet served as the background diet for all treatment groups. Phases were separated by 4-week washout periods. Fecal samples were collected at the end of each intervention phase and subjected to Illumina sequencing of 16S rRNA genes. Results revealed that at the phylum level, supplementation of 3 g/d HMW β-glucan increased Bacteroidetes and decreased Firmicutes abundances compared to control (P < 0.001). At the genus level, consumption of 3 g/d HMW β-glucan increased Bacteroides (P < 0.003), tended to increase Prevotella (P < 0.1) but decreased Dorea (P < 0.1), whereas diets containing 5 g LMW β-glucan and 3 g LMW β-glucan failed to alter the gut microbiota composition. Bacteroides, Prevotella, and Dorea composition correlated (P < 0.05) with shifts of CVD risk factors, including body mass index, waist circumference, blood pressure, as well as triglyceride levels. Our data suggest that consumption of HMW β-glucan favorably alters the composition of gut microbiota and this altered microbiota profile associates with a reduction of CVD risk markers. Together, our study suggests that β-glucan induced shifts in gut microbiota in a MW-dependent manner and that might be one of the underlying mechanisms responsible for the physiological benefits of β-glucan.

Pressurized aqueous ethanol extraction of β-glucans and phenolic compounds from waxy barley

Beta-glucans and phenolics were extracted from waxy barley using pressurized aqueous ethanol in a stirred batch reactor at 25bar and 500rpm. The effect of temperature (135–175°C), extraction time (15–55min) and ethanol content (5–20%) was evaluated. Temperature had an opposite effect on the extraction of both compounds. The higher the temperature, the lower the β-glucan extraction yield due to fragmentation, but a significant increase on the phenolic recovery was observed. Long extraction times favored the extraction of β-glucans at low temperatures and phenolics at any temperature. The ethanol content was not statistically significant on the β-glucan extraction, but helped to maintain the molecular weight of the extracted β-glucan. To obtain liquid extracts rich in high molecular weight β-glucans and phenolics, mild conditions of 151°C, 21min and 16% ethanol are needed, leading to 51% β-glucan extraction yield with a molecular weight of 500–600kDa and 5mgGAE/g barley.

Dynamics of Phase Separation in Oat β-glucan/Milk Mixtures Studied with Ultrasonic and Diffusing Wave Spectroscopy

When high molecular weight β-glucan is added to milk, macroscopic phase separation occurs due to thermodynamic incompatibility between mixed-linkage β-glucan and milk proteins. In this research, the evolution of microphase separated domains was investigated using ultrasonic and diffusing wave spectroscopy. It was possible to follow the dynamics of phase separation, in situ, without dilution. Immediately after mixing, there was a significant decrease in the initial turbidity of the mixtures, measured using diffusing wave spectroscopy, even at concentrations below macroscopic phase separation. At low and intermediate concentrations of β-glucan (0.1–0.2 w/w) the turbidity parameter, 1/l*, changed after mixing, because of rearrangements within the protein rich domains and growth of the phase separated domains. At high concentrations of β-glucan (0.6 % w/w), after an initial change in 1/l*, no further changes in turbidity were observed, because of the high viscosity of the mobile phase and the low diffusivity of the micelles due to crowding within the phase separated domains. Similar conclusions were drawn by observing the changes in ultrasonic attenuation, when probing at larger length scales. By using these two spectroscopic techniques it was possible to obtain complementary information on the dynamics of phase separation in β-glucan milk mixtures, and determine which systems still show rearrangements within the domains after mixing.

Molecular weight of barley β-glucan does not influence satiety or energy intake in healthy male subjects

Previous studies have shown the ability of high molecular weight barley β-glucan with increased viscosity to attenuate glycemic response, gastric emptying and in vitro starch digestion. The main objective of this study was to investigate the effect of molecular weight of barley β-glucan in a semisolid meal on energy intake and subjective feelings of hunger, fullness, desire to eat and prospective food consumption in healthy male subjects. In a randomised, controlled, crossover trial, 23 healthy male subjects (BMI 24.2 ± 2.5 kg/m2) tested soups equivalent to 25 g available carbohydrate containing high or low molecular weight barley β-glucan (~3 g) as preload after a standard breakfast. The viscosity of soup with high molecular weight β-glucan was 350 Pa·s whereas the soup with low molecular weight β-glucan had a viscosity of 100 Pa·s. Appetite ratings before and for two hours after consumption of β-glucan soups and subsequent ad libitum energy intake at lunch were recorded and compared with a control soup with no β-glucan. There was no significant difference in food intake at the ad libitum meal or for the remainder of the day following consumption of the three test foods (p > 0.05). Similarly, there were no significant differences (p > 0.05) in hunger, fullness, desire to eat or prospective food consumption following β-glucan soups. The current study provides evidence that the molecular weight of barley β-glucan may not impact on perceived feelings of hunger or food intake at the current dose and viscosity.

Textural and Rheological Properties of Oat Beta-Glucan Gels with Varying Molecular Weight Composition

The impact of oat β-glucan concentration and molecular weight (MW) on gel properties was investigated. Mixed MW gels/viscous solutions at 3, 4, and 5% β-glucan with high molecular weight (HMW):low molecular weight (LMW) ratios of 0:100, 25:75, 50:50, 75:25, and 100:0 were evaluated. The 100:0 and 50:50 gels had the lowest tan δ values. The 50:50 gels had the highest storage moduli (G'), whereas 100:0 solutions did not gel. Peak melting temperature (TP) was highest for 0:100 gels and decreased with the addition of HMW β-glucan. Hardness, at 40% compression, increased with concentration, and 25:75 and 50:50 gels were hardest at each concentration. Ordered microstructure, apparent in 0:100 gels, diminished with HMW β-glucan addition. Glucose addition resulted in lower tan δ values and firmer, harder gels compared to gels without glucose. Thus, the textural properties and melting profiles of β-glucan gels can be manipulated by adjusting the ratios of molecular weight fractions or addition of sugar for different applications.