Β-glucan Solution Research Articles

Molecular conformation and dilute solution properties of barley β-glucan: unveiling β-glucan as a highly flexible biopolymer under different processing conditions

BackgroundThe functional properties of food fluids containing hydrocolloids are influenced by temperature, soluble salts, pH and the presence of sugars. In this research, the properties of a dilute barley β-glucan (BBG) solution were evaluated in the presence of various factors. Different models were explored to determine the intrinsic viscosity of BBG.ResultsThe results indicated that the models of Higiro and Tanglertpaibul–Rao were more efficient in determining the intrinsic viscosity of BBG at different temperatures, different pH, the presence of sodium chloride, calcium chloride, and sucrose. Every 10 °C increase in temperature from 25 to 65 °C caused a decrease in intrinsic viscosity by 7.8, 10, 5.7 and 7.2%, respectively. In relation to the non-ionic structure of BBG, the presence of monovalent and bivalent salts had a negligible effect on reducing the intrinsic viscosity. The increase in pH from 3 to 7 caused a rise in intrinsic viscosity. But a further increase in pH, up to 9, caused a decrease in intrinsic viscosity. However, these changes were not significant and indicated that the non-ionic structure of BBG was independent of the pH. Since the constant b values of BBG were close to 1 at all temperatures, salt concentrations, different pH values and different sucrose concentrations, it can be assumed that the structure of BBG in the dilute range was close to the random coil conformation.ConclusionsThe values of flexibility index and activation energy for BBG were calculated as 789.52 and {0.65times 10}^{7} J/kmole, respectively, which indicated that this hydrocolloid was highly flexible in different environmental conditions and it was independent of the processing temperature. Therefore, BBG can be recommended as a natural thickener in food-related fluids.Graphical

Role of β-glucan content, molecular weight and phytate in the bile acid binding of oat β-glucan

There is controversy about the role of viscosity and co-migrating molecules on the bile acid binding of beta-glucan. Thus, this study aimed to investigate the impact of β-glucan molecular weight and the content of both β-glucan and phytate on the mobility of bile acids by modelling intestinal conditions in vitro. Two approaches were used to evaluate factors underlying this binding effect. The first studied bile acid binding capacity of soluble β-glucan using purified compounds. Viscosity of the β-glucan solution governed mainly the mobility of bile acid since both a decrease in β-glucan concentration and degradation of β-glucan by enzyme hydrolysis resulted in decreased binding. The second approach investigated the trapping of bile acids in the oat bran matrix. Results suggested trapping of bile acids by the β-glucan gel network. Additionally, hydrolysis of phytate was shown to increase bile acid binding, probably due to better extractability of β-glucan in this sample.

Freeze-thaw Properties of β-glucan Gels with Different Concentrations

The β-glucan gel was prepared in freeze-thawing method. The formation of freeze-thawed gel was studied by low-field nuclear magnetic resonance (NMR). Three relaxing components with different transverse relaxation time (T21, T22 and T23) were founded in the β-glucan system. With the increase of the number of freezing and thawing, the T22 of barley β-glucan increased rapidly after 5th freezing and thawing and A22 increased significantly after 3th freezing and thawing. The relaxation time T21, T22 and T23 rose first and then did not change. A21 and A22 first increased and then changed little while A23 first declined and then changed little. By performing the principal component analysis on the relaxation distribution curve, β-glucan gel of different concentrations. The rheological study showed that β-glucan gel with higher mass fraction has a larger elastic viscous modulus. This indicated that it formed more more physical ross-linked structure in gel. The results of scanning electron microscopy showed that β-glucan solut ion with higher mass fraction formed structure compact gel while β-glucan solution with lower mass fraction formed structure loose gel.

Preparation of Grain β-glucan Gel and Characteristics of Its Slow-release

The β-glucan freeze-thaw gel has been used as a carrier to release curcumin. The freeze-dried gel has the ideal sustained release following 5% β-glucan solution by adding 1% β-glucan quality curcumin, repeated freezing and thawing 8 times. The Peppas equation can significantly describe the release mechanism of curcumin in the β-glucan gel. This study further shows that the release of curcumin in the oat β-glucan gel is the Fick diffusion mechanism and coated barley β-glucan is a non-Fick release. Trying to use β-glucan as a completely natural drug delivery carrier opens up new ideas for the use of β-glucan.

Slow Release Characteristics of β-Glucan

β-glucan freeze-thaw gel was used as a carrier to release curcumin. The results showed that the freeze-dried gel had the ideal sustained release following 5% β-glucan solution by adding 1% β-glucan quality curcumin, repeated freezing and thawing 8 times. The Peppas equation can significantly describe the release mechanism of curcumin in the β-glucan gel. This study further demonstrated that the release of curcumin in the oat β-glucan gel is the Fick diffusion mechanism and coated barley β-glucan is a non-Fick spread.

Catalytic Efficiency, Structure, and Recycling Behavior of Electrospun Polyvinyl Alcohol-Xylanase Fibers Cross-Linked by Glutaraldehyde

A versatile and effective method of producing polyvinyl alcohol (PVA)-xylanase (XY) fibers cross-linked by glutaraldehyde vapor (GA) is reported in the present study. Crosslinking was performed for 30, 60, 90, and 180 min. The morphology, structure, and thermal stability of the fibers were investigated by scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FTIR), and thermogravimetric analyses (TGA). The enzymatic activity was studied under different storage time and reutilization cycles. The enzyme’s ability to reduce the turbidity of a standard β–glucan solution was also verified. Cross-linked fibers presented denser and more compacted structures. There was an improvement in thermal properties as well as in the recycling and storage efficiency of cross-linked XY–PVA fibers, compared to their non-cross-linked counterparts. Free and 180 min-cross-linked immobilized enzymes were able to reduce the turbidity of the β-glucan solution by a similar degree.

Effects of the incorporation of β-glucans in chicken breast during storage

β-glucans are cereal-derived soluble fiber compounds that elicit health benefits when consumed in amounts of 0.75 g/serving. The use of β-glucans in whole muscle meat products, such as chicken breast, is unexplored and needs clarification at a discovery level. The objective of this study was to evaluate the incorporation of β-glucan in the whole muscle chicken breast and identify changes in physical, chemical, textural, microbiological, and thermal properties during 9 D of aerobic storage at refrigeration temperatures. Treatments were 1) control (no salt or β-glucan added; CON), 2) salt solution (2% NaCl and 0.2% phosphate curing solution; SALT), 3) β-glucan solution (1.5% β-glucan; βG), and 4) combination of salt and β-glucan solutions (2% NaCl, 0.2% phosphate, and 1.5% β-glucan; SALT+βG). The target injection level was 20%, however the average uptake level was 8.15%. Color, pH, shear force, and bacteria count were minimally affected by treatment during the 9 D of aerobic storage at 4°C. Cooking loss (P < 0.01) was greater in CON samples compared to all other treatments indicating the presence of salt or fiber or both improved water retention. The β-glucan concentration in uncooked chicken following injection was 0.125 g/100 g product and 0.133 g/100g product in βG and SALT+βG treatments, respectively. Following cooking, the β-glucan concentration was 0.010 g/100g product and 0.004 g/100g product in βG and SALT+βG treatments, respectively. There was no storage day effect (P = 0.42) for the β-glucan concentration in cooked product, therefore it was assumed that during cooking, β-glucan concentration in whole muscle injected products was lost. Finally, thermal behavior measured with a differential scanning calorimeter indicated that there were only minimal differences, although some significant, among treatments in this study. Overall, the application of β-glucan injection in whole chicken breast was not detrimental to product quality and actually improved water retention levels. However, new methods need to be developed for the incorporation of β-glucan in injected whole muscle meat product so that β-glucan can be retained during and after cooking.

Effect of β-Glucan Stabilized Virgin Coconut Oil Nanoemulsion on Properties of Croaker Surimi Gel

ABSTRACTEffects of virgin coconut oil (VCO) nanoemulsion stabilized by β-glucan and β-glucan solution at final β-glucan levels of 5–20% (based on solid weight of surimi) on croaker surimi gel were comparatively studied. Increases in breaking force, deformation, and fracture constant were found in surimi gel containing VCO nanoemulsion stabilized by 5% β-glucan, whereas a decrease in all properties was observed as the level of β-glucan in nanoemulsion increased. The addition of β-glucan solutions led to continuous decrease in breaking force, deformation, and fracture constant, compared to the control. Addition of both β-glucan stabilized nanoemulsion and β-glucan solutions resulted in decrease in viscoelastic moduli. Power law model represented viscoelastic behavior of all the gels. Expressible moisture content decreased, while whiteness increased with the addition of β-glucan-stabilized nanoemulsion, compared with gel containing VCO. However, both expressible moisture content and whiteness increased with the addition of β-glucan solutions, at all levels used. Addition of β-glucan-stabilized nanoemulsion resulted in finer gels compared to the control gel added with only VCO. Generally, overall likeness score increased for gel containing VCO nanoemulsion stabilized by 5% β-glucan. The surimi gel containing both medium chain fatty acids and β-glucan, functional ingredients, could be developed as a new product.

Rheological investigations of beta glucan functionality: Interactions with mucin

The shear and extensional rheology of β-glucan and mucin mixtures have been studied as to probe the functionality-related thickening effects of consumed β-glucan during food digestion. Mucins, the main viscosity-inducing components of oral and gastrointestinal fluids, can increase the shear viscosity of β-glucan solutions, e.g. when 3% mucin is added into 1% β-glucan, the shear viscosity increases from 0.4 Pa s (1% β-glucan) to 2 Pa s at a shear rate of 0.1 s−1. The 3% mucin contributes 1.6 Pa s in the presence of β-glucan, which is nearly 16 times of the viscosity induced by 4% mucin alone at the same shear rate. Mucin affects the extensional viscosity in a similar way, e.g. incorporation of 2% mucin into a 2% β-glucan system increases the extensional viscosity from 4 Pa s to 8 Pa s. Substitution of β-glucan for an equal concentration of mucin results in the decrease of the shear and extensional viscosities: Α 4% β-glucan solution has a maximum extensional viscosity of 92 Pa s; substitution of 1% β-glucan for 1% mucin (1% mucin+3% β-glucan) reduces the maximum recorded extensional viscosity to 36 Pa s; this is further reduced down to 8 Pa s at 2% mucin+2% β-glucan, and then on to 4 Pa s at 3% mucin+1% β-glucan, and to 0.8 Pa s at 4% mucin. A similar trend is observed for the shear viscosities. The shear and extensional moduli and the extensional relaxation times also follow such patterns. The Trouton ratio values are lower than 100, that is they are not as high as in other food hydrocolloids; this strongly suggests a fine in vivo interplay between shear and extensional viscosities. The effect of mucin on β-glucan solutions rheology is primarily attributed to excluded-volume interactions, which increase the effective concentration of the glucans. The implications of the above on the rheology-related functionality of β-glucans are discussed.

Characterization of cereal β-glucan extracts: Conformation and structural aspects

Several health benefits have been established for cereal mixed-linkage β-glucan of high molar mass (M), and are said to be attributed to the ability of β-glucan to form viscous slurries in the gut. As no comprehensive understanding exists yet, the characterization of β-glucan solution behavior is crucial. β-Glucan was characterized in terms of M, molecular size and conformation characteristics in aqueous solutions utilizing asymmetric flow field-flow fractionation (AF4) coupled to multi-angle light scattering (MALS) and differential refractive index (dRI) detectors. Polymers and aggregates were investigated using conformational data from comparing hydrodynamic radii (rhyd, from AF4) and root-mean-square radii (rrms, from MALS), Kratky plots (from MALS) and persistence length determination (from small-angle x-ray scattering (SAXS)). The aggregated structures were also analyzed with cryo-transmission electron microscopy (cryo-TEM). The results show the presence of highly aggregated structures in aqueous solution, in addition to dissolved, highly polydisperse polymers. The structural and conformational properties of the aggregates are different between oat and barley β-glucan. While oat β-glucan seems to be aggregated in a widely distributed, loose structure, barley β-glucan showed surprisingly dense and well-defined aggregates.

Evaluation of the Incorporation of β-Glucans in Whole Muscle Chicken Breast

ObjectivesThe use of soluble fiber (β-glucans) incorporated into whole muscle meat products is still unexplored and needs clarification on a number of factors including 1) if incorporation can be achieved, 2) possible levels of incorporation, 3) stability and bioavailability under conditions of storage and cooking, and 4) influence on the quality characteristics of the meat. Therefore, this study evaluated the incorporation of soluble fiber (β-glucans) in whole muscle chicken meat and identified changes in physical-chemical, textural, and microbiological properties during 9 d of storage under refrigeration at 4°C.Materials and MethodsBarley β-glucan solutions were incorporated by injection into whole muscle chicken breast 48 h after slaughter. Three chicken breast samples were injected with a handheld injector with target pump uptake of 20% for each treatment. Treatments were injected at 4°C and included 1) a salt solution (2% NaCl and 0.2% sodium tripolyphosphate (STPP); Treatment A), 2) a β-glucan solution (1.5% of β-glucan; Treatment B), and 3) a combination of salt and β-glucan solution (2% NaCl, 0.2% STPP, and 1.5% of β-glucan; Treatment C). Three independent replications were produced for each treatment. The treatments were injected at 4°C into the chicken breast samples. The samples were stored under refrigeration and evaluated at d 1, 6, and 9 for pH, cooking loss, instrumental color, shear force, microbiology, and thermal behavior by differential scanning calorimetry (DSC). One-way ANOVA analysis and means separation using a Duncan test comparison adjustment were performed using Statistica version 7.0. Statistical significance was assumed at P < 0.05.ResultsAbsorption of treatments was 8.15 ± 1.38% (m/m) without a significant difference among treatments, indicating a low absorption capacity of the samples. The maximum amount of β-glucan concentration remaining in the chicken breast after injection was 0.59 ± 0.1%. Cooking loss was less (P < 0.05) in Treatment C on d 6 and 9 compared with Treatment A and Treatment B. Shear force values were between 18 and 25 Newton (N) during storage. Shear force values were less (P < 0.05) in Treatment C samples (d 1 and 6) and Treatment A samples (d 9) when compared with other treatments on given days. No differences (P > 0.05) among treatments were observed in microbiology analyses. Coliforms decreased and psychrotrophic bacteria increased in all treatment groups during the storage period. After cooking, the maximum amount of β-glucan concentration that remained in the chicken breast was less than 0.1%, indicating that soluble fiber concentration is greatly impacted by cooking of whole muscle products injected with both β-glucans alone and in combination with a salt solution.ConclusionThe application of β-glucans in whole muscle chicken breast did not present advantages in cooking loss with respect to samples injected with salt alone. Under the conditions evaluated, incorporation of β-glucans into whole muscle chicken did not present detrimental effects to product quality or safety. However, after cooking, the fiber concentration in the final product was reduced to levels where it would not be sufficient for health benefits or for the product to be declared as a source of dietary fiber. Therefore, challenges to increase the concentration of dietary fiber in whole muscle meat products continues.

بهینهیابی شرایط استخراج آبی بتاگلوکان از جو بدون پوشینه رقم لوت به روش سطح پاسخ

در این پژوهش تاثیر شرایط استخراج شامل زمان، نسبت حلال به آرد جو و pH بر ویژگی‌های فیزیکوشیمایی، رفتار جریان، پایدارکنندگی کف و امولسیون و رنگ بتاگلوکان استخراج شده از دانه جو بدون پوشینه رقم لوت توسط طرح مرکب مرکزی و به روش سطح پاسخ تعیین گردید. نتایج تجزیه و تحلیل آماری و ضرایب مدل‌ها نشان داد که مدت زمان استخراج، نسبت حلال به آرد جو و pH اثر معنی‌داری بر بازدهی و خلوص بتاگلوکان، پایداری کف و امولسیون، ضریب قوام (k)، شاخص رفتار جریان (n) و مولفه های رنگیL*، a* و b* داشت. افزایش زمان استخراج و نسبت حلال به آرد جو اثر مطلوبی بر بازدهی و خلوص بتاگلوکان استخراج شده گذاشت که این امر خود موجب بهبود خاصیت قوام‌دهندگی و ویژگی‌های رفتار جریان آن شد. از طرفی با افزایش قدرت قوام‌دهندگی بتاگلوکان، توانایی پایدارکنندگی سیستم‌های کف و امولسیون نیز افزایش یافت. افزایش pH موجب کاهش بازدهی استخراج و افزایش خلوص بتاگلوکان گردید. بهترین شرایط استخراج زمانی حاصل شد که زمان استخراج 90 دقیقه، نسبت حلال به آرد جو 10 به 1 و pH، 33/7 بود. در این نقطه بهینه، بازدهی استخراج، 12/4 درصد؛ خلوص، 11/69 درصد؛ پایداری کف، 95/86 درصد؛ پایداری امولسیون، 77/88 درصد؛ ضریب قوام، Pa.sn 51/1؛ شاخص رفتار جریان، 62/0؛ L*، 42/73 ؛ a*، 81/0 و b*، 72/8 بود.

Impact of flavouring substances on the aggregation behaviour of dissolved barley β-glucans in a model beer

Structural polymers such as cereal β-glucan may cause various processing problems in beverage industry depending on concentration, molar size distribution and agglomeration behaviour. In this context, influences of the beer volatiles dodecanoic acid, octyl butanoate, ethyl decanoate and decyl acetate on molar mass and radii of barley β-glucan were investigated in ethanolic (4% w/w) model solution. After addition of 100mg/l ethyl decanoate and decyl acetate to the β-glucan solution, a wider-ranging molar mass distribution could be observed by means of asymmetric field-flow-fractionation. Due to agglomeration, average molar mass of β-glucan standard (MW=6.8×106g/mol) increased by 2×106g/mol (P<0.05) in solution containing decyl acetate. Furthermore, a significant growth (P<0.05) from 86 to 102nm in gyration radius was measured. The obtained results elucidate the importance of fatty acid derived flavouring substance composition in beer regarding the aggregation behaviour of β-glucan.

Viscosity based quantification of endogenous β-glucanase activity in flour

High molecular weight (MW) is a key parameter for cereal β-glucans physiological benefits like decreased serum cholesterol and attenuated post prandial blood glucose. However, the activity of endogenous flour enzymes during bread production results in a decrease of β-glucan MW. The depolymerization of a standard β-glucan solution by different flour extracts (wheat, barley and rye) was followed by measuring the viscosity decrease with a Rheometer. The slope of the inverse viscosity (1/η) against degradation time was used to quantify β-glucanase activity by comparison with slopes obtained with known concentrations of the β-glucanase Lichenase. Results correlated well with depolymerization rates estimated by HPSEC. The viscosity based method is rapid (20min per sample), accurate (≤6% variation), and a powerful screening tool for identifying flour fractions with low β-glucanase activity, treatments that can inactivate β-glucanases in flour, or the development of β-glucanase inhibitors for the use in e.g. bread making.

Editorial

Cereal β-glucan is a soluble dietary fiber and a versatile functional food ingredient, which is known to be degraded during food processing non-enzymatically. The degradation of β-glucan induced by iron(II) was investigated at different temperatures (25, 50 and 100 °C) in pure β-glucan solution. Increasing the temperature of storage enhanced the formation of hydroxyl radical induced by iron(II), hence causing more intense β-glucan degradation. β-Glucan was able to reduce iron(III) into iron(II) allowing the formation of hydroxyl radical to be maintained up to 24 h. Moreover, the addition of ascorbic acid accelerated the degradation of β-glucan to the same extent as heating at 100 °C. Thus, both heating and the presence of a reducing agent enhanced the deleterious effect of iron(II) on β-glucan in an aqueous system. These factors need to be considered when processing functional foods that are enriched with β-glucan.

Effect of the temperature on the degradation of β-glucan promoted by iron(II)

Cereal β-glucan is a soluble dietary fiber and a versatile functional food ingredient, which is known to be degraded during food processing non-enzymatically. The degradation of β-glucan induced by iron(II) was investigated at different temperatures (25, 50 and 100 °C) in pure β-glucan solution. Increasing the temperature of storage enhanced the formation of hydroxyl radical induced by iron(II), hence causing more intense β-glucan degradation. β-Glucan was able to reduce iron(III) into iron(II) allowing the formation of hydroxyl radical to be maintained up to 24 h. Moreover, the addition of ascorbic acid accelerated the degradation of β-glucan to the same extent as heating at 100 °C. Thus, both heating and the presence of a reducing agent enhanced the deleterious effect of iron(II) on β-glucan in an aqueous system. These factors need to be considered when processing functional foods that are enriched with β-glucan.

열처리 온도에 따른 보리 β-Glucan의 이화학적 특성

This study was performed to investigate the changes of total and soluble β-glucan contents, purity, and physical characteristics of three heated barley varieties: Saessalbori (SSB), Saechalssalbori (SCSB), and Hinchalssalbori (HCSB). The barleys were heated at different temperatures of 110, 120, 130, 140 and 150℃ for 2 hours. The total β-glucan contents of raw SSB, SCSB, and HCSB were 8.40, 7.77 and 8.28%, and the soluble β-glucan contents were 4.79, 4.14, and 4.61%, respectively. After heating at 130℃, the total β-glucan contents increased to 11.59, 14.6, and 13.36%, as did the soluble β-glucan contents to 4.21, 7.96, and 7.23%, respectively. The purities of soluble β-glucan of the raw barleys were 35.11, 32.74 and 25.62%, but after heating at 150℃, it increased to 83.43, 91.02, and 88.01%, respectively. The molecular weight and viscosity of the β-glucan solution decreased with increasing heating temperature. The re-solubility of raw barley β-glucan was about 50%, but it was increased to 97% with increasing heating temperature. These results suggest that heating of β-glucan can improve the utilization of barley β-glucan.

Highlights from the Macromolecular X-ray Crystallography Facility at Pennsylvania State University (a) crystal structures of bacterial expansin in complex with cellohexoase and β-glucan (b) solution scattering and crystal structure of sorbitol dehydrogenase with a substrate (c) computation model of human Ron receptor with its juxta-membrane domain and (d) model of phospholipase a2 with procyanidins

Highlights from the Macromolecular X-ray Crystallography Facility at Pennsylvania State University (<i>a</i>) crystal structures of bacterial expansin in complex with cellohexoase and β-glucan (<i>b</i>) solution scattering and crystal structure of sorbitol dehydrogenase with a substrate (<i>c</i>) computation model of human Ron receptor with its juxta-membrane domain and (<i>d</i>) model of phospholipase a2 with procyanidins

Oxidation of oat β-glucan in aqueous solutions during processing.

The study investigated carbonyl group formation along the chain and the chain cleavage of cereal β-glucan during heat treatments, high pressure homogenisation, cold storage and ascorbic acid treatment of aqueous solutions of this soluble dietary fibre. The carbonyl group content and its distribution along the chain were simultaneously determined with the chain cleavage using a HPSEC/labelling method, originally developed for water-insoluble cellulose. Ascorbic acid treatment resulted in a relatively high degree of carbonyl content and extensive degradation of β-glucan, even in concentrations typically found in foods. The thermal oxidation of the β-glucan was considerable at 120°C in a β-glucan solution with co-extracted compounds from oat ingredient, and in the highly purified solutions in presence of ferrous ions. Oxidation also probably contributed to the molecular properties during high pressure homogenisation, even thou the main degradation mechanism is the hydrolysis caused by mechanical energy. In addition to the cleavage of the β-glucan chain, the formation of compact, high molar mass species or molecule clusters were obtained in the study after ascorbic acid, heat (120°C) and homogenisation treatments.

Oxidative and radical mediated cleavage of β-glucan in thermal treatments

Oat β-glucan is a dietary fibre with solid and well evidenced health benefits. Its beneficial properties, however, largely depend on its molecular properties and processing history. In this study, the cleavage of oat β-glucan in heat treatments (95°C and 120°C) and role of oxidative reactions were investigated in highly purified β-glucan solution and in β-glucan extracts of oat bran. Both viscosity and molar mass decreased during the heat-treatments, and the degradation was more intensive in the extract solutions with co-extracted phytates, proteins, minerals and other compounds. Oxidative reactions, most likely Fenton chemistry, played a role in the degradation, since oxidative free radicals and hydrogen peroxide were formed during the heating, and the addition of an oxidation catalyst (Fe2+-ions) accelerated the thermal degradation. Inhibition of the oxidative reactions by antioxidants appeared to be challenging; for example, ascorbic acid alone accelerated the thermal degradation of β-glucan, but its use with sulfite slowed down the rate of thermal degradation.