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

Partial replacement of saturated fats in liver pâté by an olive oil-in-water emulsion containing β-glucan shows no compromise in sensory and storage oxidation of lipids and protein

BACKGROUND

The consumption of olive oil has been shown to have a positive effect on preventing obesity and hypertension. At the same time, it is recommended to avoid processed meat products as they contain saturated fats. The inclusion of highly unsaturated lipids in food products can lead to rapid oxidation and deterioration of sensory characteristics. The objective of the current work was to encapsulate olive oil and incorporate it into traditional Polish liver pâté. The oil-in-water emulsions were formulated with varying levels of oat β-glucan and were evaluated for droplet size, pH, encapsulation efficiency and rheology. The liver pâtés made using the emulsions with and without β-glucan were then evaluated for pH, texture, colour, lipid and protein oxidation, thermal stability and sensory properties.

RESULTS

The results showed that the oil-in-water emulsions had a 100% encapsulation rate of olive oil after 30 days of storage at 4 °C, regardless of the presence of β-glucan. Although the texture of the emulsion-enriched liver pâté was different from that of the control, this difference was reduced when β-glucan was added to the emulsion and then to the pâté matrix.

CONCLUSION

Replacing 50% of animal fat with an olive oil emulsion enriched with β-glucan did not result in any compromise of sensory properties, increase lipid or protein oxidation. These results suggest that it is possible to replace saturated lipids with omega-3-rich olive oil. © 2024 Society of Chemical Industry.

Distinctions in structure, rheology, antioxidation, and α-glucosidase inhibitory activity of β-glucans from different species

To investigate the distinctions between β-glucans from different species, Lentinula edodes β-glucan (LG), yeast β-glucan (YG), and oat β-glucan (OG) were extracted with hot water and determined as β-d-glucopyranose form by HPLC and FT-IR analysis. The molecular weight (Mw) of LG, YG, and OG was 670 kDa, 341 kDa, and 66 kDa, respectively. Scanning electron microscopy exhibited different micro surfaces of three β-glucans and the relative crystallinity of YG was the highest (29.8 %), followed by that of LG (23.2 %) and OG (20.3 %) determined by X-ray diffraction. Congo red analysis and atomic force microscopy showed that LG and YG have triple helical structures. The apparent viscosity, storage modulus (G'), and loss modulus (G") of β-glucans were increased with the increase of Mw. DPPH·, ABTS+·, HO·, and reducing power assays showed that β-glucans from different species exhibited different antioxidant activities, and the DPPH· scavenging rate of 2 mg/mL LG reached >80 % higher than that of YG and OG. The α-glucosidase inhibitory activity of OG was better than YG and LG. In summary, β-glucans from different species have different structures, physicochemical properties, and physiological functions, which provides theoretical evidence for the precise processing and utilization of β-glucan.

Understanding the health benefits and technological properties of β-glucan for the development of easy-to-swallow gels to guarantee food security among seniors

The world's population is growing rapidly and the number of elderly people with undernutrition and malnutrition is increasing. Common health problems among seniors are cardiovascular, inflammatory, gastrointestinal, and cognitive disorders, cancer, diabetes, psychological and dental problems. The food industry is trying to meet the demands of an aging society, but these efforts are not sufficient. New strategies are needed, and they demand foods development with modified textures that are easy to swallow, such as gels suitable for seniors. Depending on the specific needs of the elderly, bioactive compounds with health benefits should be included in food systems. Novel foods may play an important role in the prevention, maintenance, and treatment of age-related diseases. One of the most studied bioactive compound is β-glucan, a polysaccharide with approved health claims confirmed by clinical trials, such as "β-glucan contributes to the maintenance of normal blood cholesterol levels" and "the consumption of β-glucan from oats or barley contributes to the reduction of postprandial glucose spikes." In this review, the health benefits, and technological properties of β-glucan for the development of senior-friendly ready-to-swallow gels were described. In addition, some patents and studies conducted in connection with the development of the gel systems were collected.

Insights into the modification of physicochemical properties and digestibility of pea starch gels with barley β-glucan

The influences of barley β-glucan (BBG) on the physicochemical properties and in vitro digestibility of pea starch were investigated. BBG was found to decrease pasting viscosity in a concentration dependent manner and inhibited the aggregation of pea starch. After the presence of BBG, the gelatinization enthalpy of pea starch was decreased (from 7.83 ± 0.03 to 5.55 ± 0.22 J/g), whereas the gelatinization temperature was enhanced (from 62.64 ± 0.01 to 64.52 ± 0.14°C) according to the differential scanning calorimeter results. In addition, BBG inhibited the swelling of pea starch and amylose leaching. When amylose leached out from pea starch to form a BBG-amylose barrier, starch gelatinization was inhibited. The starch gels exhibited weak gels and shear thinning behaviors by rheological tests results. The interaction between BBG and amylose led to lower viscoelasticity and texture parameters in pea starch gels. The structure analysis results unveiled that the force between BBG and amylose was mainly hydrogen bonds. Pea starch hydrolysis was inhibited when BBG was present in the system, which was connected with the restricted starch gelatinization. These results obtained in the study would supply insights into incorporating BBG into various food systems.

Perspectives in the Application of High, Medium, and Low Molecular Weight Oat β-d-Glucans in Dietary Nutrition and Food Technology-A Short Overview

For centuries human civilization has cultivated oats, and now they are consumed in various forms of food, from instant breakfasts to beverages. They are a nutrient-rich food containing linear mixed-linkage (1 → 3) (1 → 4)-β-d-glucans, which are relatively well soluble in water and responsible for various biological effects: the regulation of the blood cholesterol level, as well as being anti-inflammatory, prebiotic, antioxidant, and tumor-preventing. Numerous studies, especially in the last two decades, highlight the differences in the biological properties of the oat β-d-glucan fractions of low, medium, and high molecular weight. These fractions differ in their features due to variations in bioavailability related to the rheological properties of these polysaccharides, and their association with food matrices, purity, and mode of preparation or modification. There is strong evidence that, under different conditions, the molecular weight may determine the potency of oat-extracted β-d-glucans. In this review, we intend to give a concise overview of the properties and studies of the biological activities of oat β-d-glucan preparations depending on their molecular weight and how they represent a prospective ingredient of functional food with the potential to prevent or modulate various pathological conditions.

Influence of polysaccharide concentration on polyphenol-polysaccharide interactions

Non-covalent interactions between polysaccharides and phenolics affect the physical properties of polysaccharide solutions. These interactions may in turn be influenced by polysaccharide-polysaccharide interactions. To test this hypothesis, we studied the influence of polysaccharide concentration (with guar, β-glucans, and xanthan) on the variations of rheological and water-binding properties upon addition of phenolics compounds (vanillin, caffeic acid, gallic acid, and epigallocatechin gallate). Addition of phenolics led to increased flow behavior index and decreased flow consistency index, with maximum effects at polysaccharide concentrations ranging between 0.6 × C* and 1.4 × C*, where C* is the critical overlap concentration of each polysaccharide. Water mobility was generally not significantly influenced by the addition of phenolics. The results showed that the ability of phenolic compounds to induce aggregation of polysaccharides in solution was strongly influenced by polysaccharide concentration around C* and therefore by polysaccharide-polysaccharide interactions.

Characterization of acid hydrolysates from barley β-glucan concentrate for their physico-chemical and rheological properties

The present study was aimed at assessing the influence of acid hydrolysis on the physicochemical and rheological properties of β-glucan concentrate. Barley β-glucan concentrate was subjected to acid hydrolysis for 30 and 60 min. The molecular weight and viscosity were observed to be a function of hydrolysis time and decreased in a duration-based approach. Significant reduction in water binding capacity and swelling power was observed after acid hydrolysis. Acid hydrolysis dramatically altered the flow properties and a Newtonian behavior was observed for HBG₆₀. The oscillatory measurements revealed enhanced visco-elasticity for HBG₃₀ solutions in comparison to its native counterpart and were greatly reliant on molecular weight and concentration. DSC measurements showed reduced thermal stability of acid hydrolysates in comparison to native β-glucan concentrate. Overall, this study provides useful information on the hydration, thermal and rheological behavior of β-glucan concentrates and could be helpful in optimizing the concentration of β-glucan concentrates in food formulations.

Relation between glycosidic linkage, structure and dynamics of α- and β-glucans in water

In a molecular dynamics simulation study of several oligosaccharides comprising of the very basic building block of carbohydrate, the α- or β-d glucopyranose units, linked by any one of the 1-3/1-4 or 1-6 glycosidic linkages, we compare and contrast their structural and dynamical properties. Results indicate that the litheness of the oligosaccharide chain is noticeably controlled by the composition, anomeric nature and glycosidic linkage type of the units. In mixed β 1-4/1-3 d-glucopyranosides, as those found in oats and barley, the ratio of the β 1-4 and β 1-3 linked residues is crucial in determining the structural and dynamical attributes. Principal component analysis (PCA) using the internal coordinates of torsion angles subtended by glycosidic oxygen atoms and subsequent K-means clustering of the dynamical space spanned by PC1 to PC2 point to the dynamical and structural disparity in the various types of oligosaccharides studied. The properties simulated in this work are meant to provide a systematic yet comparative understanding of the importance of linkage and anomericity on the oligosaccharide chain properties and are in line with some experimental structural attributes.

Evaluation of oat β-glucan-marine collagen peptide mixed gel and its application as the fat replacer in the sausage products

The food industry is currently shown the concern with low-fat products. This study aims to evaluate the properties of oat β-glucan(OG)-marine collagen peptide (MCP) mixed gels induced by high pressure at different ratios, pressures, pH levels and the superiority of application in the sausage. The results indicated that the typical gel with high levels of hardness, cohesiveness, springiness, and chewiness, as well as high water holding and oil adsorption capacities was formed using the OG/MCP ratio of 10:1 under 400 MPa at pH 6.0. The mixed gel replacing with 50% fat significantly increased the springiness and chewing(P<0.05), and sausages with 80% mixed gel were significantly juicier than that of the control sausage(P<0.05). Therefore, OG-MCP mixed gel could be used in the reformulation of low-fat meat products to enhance their safety and nutritional value.

The impact of different levels of oat β-glucan and water on gluten-free cake rheology and physicochemical characterisation

The demand for new gluten-free (GF) products is still very crucial issue in food industry. There is also a need for bioactive compounds and natural alternatives for food additives. For now, not only providing structure without gluten is major challenge, but also high sensory acceptance and nutritional value are on the top. This study is focused on the effect of high-purity oat β-glucan as a structure-making agent on physicochemical and sensory properties of gluten-free yeast leavened cake. The response surface methodology (RSM) was used to set the design of the experiment. Water and oat β-glucan were chosen as independent variables. Enzymatic extraction was conducted in order to obtain pure oat β-glucan (approx. 85%). Physicochemical and microstructure analyses, and a consumer hedonic test were carried out to check the quality of the final product. As a last step, verification was undertaken to compare the predicted and experimental values of the results. The results showed that the optimisation process was crucial in obtaining high-quality, gluten-free yeast leavened cake. The optimised amounts of water and oat β-glucan were 66.12% and 2.63% respectively. This proves that the application of oat β-glucan to gluten-free products is possible and gives positive results in terms of texture, volume and sensory acceptance. Due to oat β-glucan’s pro-health benefits, the final product can be seen as a functional alternative for common gluten-free products in the market.

Structures, fabrication mechanisms, and emulsifying properties of self-assembled and spray-dried ternary complexes based on lactoferrin, oat β-glucan and curcumin: A comparison study

Protein-polyphenol-polysaccharide non-covalent ternary complexes possess many unique structural and functional properties. However, rare work is available to fabricate the neutral polysaccharide-based ternary complexes. Herein, the ternary complexes composed of lactoferrin (LF), oat β-glucan (OG), and curcumin (Cur) with three binding sequences were successfully developed through self-assembly technique and spray drying technique, respectively. Spray drying could enhance the extent of the intermolecular associations among LF, OG, and Cur, leading to the formation of ternary complexes with smaller particle sizes and lower turbidities. Cur can be loaded in LF-OG complexes to form an amorphous complex through the intermolecular interactions (mainly hydrophobic interactions and hydrogen bonding). The ternary complexes can be used as potential emulsifiers to stabilize oil-in-water Pickering emulsions. The emulsifying capacity (to enhance physical stability) of the complexes was in the order as follows: the spray-dried ternary complexes > the spray-dried LF-OG complexes > the self-assembled ternary complexes > the self-assembled LF-OG complexes. The structural and functional properties (e.g., emulsifying property) of OG-based ternary complexes can be controlled by adjusting the binding sequences. These results will broaden our current understanding of protein-polyphenol-polysaccharide ternary complexes and provide more applications of OG in food, cosmetics, and pharmaceutical industries.

Pasting, rheological, and dough mixing behavior of rice flour as affected by the addition of native and partially hydrolyzed β-glucan concentrate

This study was aimed at evaluating the potential of barley β-glucan concentrates (native and partially hydrolyzed) in modifying the techno-functionality of rice flour dough. β-Glucan concentrate was partially hydrolyzed to obtain a low molecular weight polymer and their influence on the pasting, rheological, and thermal properties of rice dough were assessed. Hydration, thermal, and pasting properties were significantly modified with the added β-glucans. The rice dough supplemented with β-glucan concentrates showed improved viscoelastic and creep behavior and the effectiveness of β-glucans in imparting strength to rice dough depended on its molecular weight. Hydrolyzed β-glucan concentrates having low molecular weight increased dough elasticity to the greater extent in comparison to native β-glucan concentrates. The micrographs of supplemented dough showed a strong and dense network indicating improved structure and strength.

The properties and formation mechanism of oat β-glucan mixed gels with different molecular weight composition induced by high-pressure processing

High pressure, an emerging nonthermal technology has been widely applied in food product modifications. The effects of oat β-glucan concentration and pressure on the properties of mixed gels with the different ratios of varying molecular weight (MW) β-gulcan induced by HPP were investigated. The results showed that the lowest β-glucan concentration forming a gel was 15% at 200 MPa, while 8% β-glucan was required to form a gel at 500 MPa. The gel intensity and textural properties increased with elevating β-glucan total concentration and pressure. The characteristic compact and smooth mixed gel formed with 12% β-glucan at a ratio of 50:50 at 400 MPa for 30 min. Under this optimal parameters, the mixed solution showed a relatively lower particle size and turbidity, and the hydrogen bonding and electrostatic interaction played the main role during the gel formation process by high pressure. In addition, the core molecular structure of β-glucan was maintained in the mixed gel formed under the optimal parameters.

A Concise Review on the Molecular Structure and Function Relationship of β-Glucan

β-glucan is a non-starch soluble polysaccharide widely present in yeast, mushrooms, bacteria, algae, barley, and oat. β-Glucan is regarded as a functional food ingredient due to its various health benefits. The high molecular weight (Mw) and high viscosity of β-glucan are responsible for its hypocholesterolemic and hypoglycemic properties. Thus, β-glucan is also used in the food industry for the production of functional food products. The inherent gel-forming property and high viscosity of β-glucan lead to the production of low-fat foods with improved textural properties. Various studies have reported the relationship between the molecular structure of β-glucan and its functionality. The structural characteristics of β-glucan, including specific glycosidic linkages, monosaccharide compositions, Mw, and chain conformation, were reported to affect its physiochemical and biological properties. Researchers have also reported some chemical, physical, and enzymatic treatments can successfully alter the molecular structure and functionalities of β-glucan. This review article attempts to review the available literature on the relationship of the molecular structure of β-glucan with its functionalities, and future perspectives in this area.

In vitro assessment of oat β-glucans nutritional properties: An inter-laboratory methodology evaluation

The purpose of this inter-laboratory study was to test the repeatability and reproducibility of an in vitro method aimed at analyzing the physicochemical properties under physiological conditions of β-glucans from foods. After evaluating β-glucans molar mass and quantification methods using five β-glucan controls, four laboratories ran six oat-based products through in vitro digestion, measured β-glucans solubility and viscosity and molar mass of solubilized β-glucans. The determination of the molar mass of β-glucan controls, their viscosity in solution and β-glucans content in food samples exhibited relative standard reproducibility of 20.9-40.9%, 10.2-40.9% and 2.3-14.8%, respectively. After in vitro digestion, relative standard reproducibility ranged 12.1-60.0%, 12.2-64.3% and 9.7-36.3% for molar mass of extracted β-glucans, their viscosity and their solubility, respectively. Although the characterization methods were satisfactory within the limits of current technology, the in vitro extraction contributed significantly to the uncertainty of final characterization.

Use of the Extended Fujita method for representing the molecular weight and molecular weight distributions of native and processed oat beta-glucans

Beta 1-3, 1-4 glucans ("beta-glucans") are one of the key components of the cell wall of cereals, complementing the main structural component cellulose. Beta-glucans are also an important source of soluble fibre in foods containing oats with claims of other beneficial nutritional properties such as plasma cholesterol lowering in humans. Key to the function of beta-glucans is their molecular weight and because of their high polydispersity - molecular weight distribution. Analytical ultracentrifugation provides a matrix-free approach (not requiring separation columns or media) to polymer molecular weight distribution determination. The sedimentation coefficient distribution is converted to a molecular weight distribution via a power law relation using an established procedure known as the Extended Fujita approach. We establish and apply the power law relation and Extended Fujita method for the first time to a series of native and processed oat beta-glucans. The application of this approach to beta-glucans from other sources is considered.

Chia and oat emulsion gels as new animal fat replacers and healthy bioactive sources in fresh sausage formulation

This paper examines the effect of emulsion gels (EG) prepared with chia (CEG) and oats (OEG) used as animal fat replacers in reduced-fat fresh sausages (longaniza) (LRF) during chilled storage. Reduced-fat samples were reformulated with CEG and OEG, (LRF/CEG and LRF/OEG respectively). Normal (LNF/P) and reduced-fat (LRF/P) (all-pork-fat) sausages were used as controls. Nutritional composition and microbiological, technological and sensory characteristics of sausages were evaluated. The presence of an EG affected (P<0.05) the concentrations of some minerals and amino acids in sausages. CEG improved MUFA and PUFA contents. Cooking loss was lower (P<0.05) in LRF/CEG and LRF/OEG than in the controls. Of all the reduced-fat samples, Kramer shear force values (KSF) were highest (P<0.05) in the ones containing an EG. KSF generally increased (P<0.05) over storage in all samples. The microbial count was significantly affected by the use of CEG. Sensory properties were affected by the incorporation of an EG, but all sausages were judged acceptable.

Emulsion gels as potential fat replacers delivering β-glucan and healthy lipid content for food applications

Oat emulsion gels and oil-free oat gels were formulated with varying proportions of oat bran/olive oil (from 12/40 to 28/0) without or with alginate or gelatin used as animal fat replacers and/or to provide β-glucan and MUFA for meat products. Composition, technological properties (thermal stability, colour, texture, etc.) and the effects of chilled and frozen storage of samples were evaluated. Depending on the proportion, samples developed for use as animal fat replacers in meat products may endow these with properties qualifying them for nutrition and health claims. No samples showed any noticeable syneresis and all showed good thermal stability. Increasing of oat bran/olive oil increased a* and reduced b* values, while differences in L* depended on the gelling agent. Penetration force (PF) and gel strength increased when the oat bran/oil ratio increased, with the highest values in the samples containing alginate or gelatin. Thermal losses and PF generally increased during chilled and frozen storage, and no significant differences were observed in colour or pH over storage.

Characterization of Oat (Avena nuda L.) β-Glucan Cryogelation Process by Low-Field NMR

Low-field nuclear magnetic resonance (LF-NMR) is a useful method in studying the water distribution and mobility in heterogeneous systems. This technique was used to characterize water in an oat β-glucan aqueous system during cryogelation by repeated freeze-thaw treatments. The results indicated that microphase separation occurred during cryogelation, and three water components were determined in the cryostructure. The spin-spin relaxation time was analyzed on the basis of chemical exchange and diffusion exchange theory. The location of each water component was identified in the porous microstructure of the cryogel. The pore size measured from the SEM image is in accordance with that estimated from relaxation time. The formation of cryogel is confirmed by rheological method. The results suggested that the cryogelation process of the polysaccharide could be monitored by LF-NMR through the evolution of spin-spin relaxation characteristics.