Characterisation of soluble and insoluble cell wall fractions from rye, wheat and hull-less barley endosperm flours

Journey of dietary fiber along the gastrointestinal tract: role of physical interactions, mucus, and biochemical transformations

Dietary fiber-rich foods have been associated with numerous health benefits, including a reduced risk of cardiovascular and metabolic diseases. Harnessing the potential to deliver positive health outcomes rests on our understanding of the underlying mechanisms that drive these associations. This review addresses data and concepts concerning plant-based food functionality by dissecting the cascade of physical and chemical digestive processes and interactions that underpin these physiological benefits. Functional transformations of dietary fiber along the gastrointestinal tract from the stages of oral processing and gastric emptying to intestinal digestion and colonic fermentation influence its capacity to modulate digestion, transit, and commensal microbiome. This analysis highlights the significance, limitations, and challenges in decoding the complex web of interactions to establish a coherent framework connecting specific fiber components' molecular and macroscale interactions across multiple length scales within the gastrointestinal tract. One critical area that requires closer examination is the interaction between fiber, mucus barrier, and the commensal microbiome when considering food structure design and personalized nutritional strategies for beneficial physiologic effects. Understanding the response of specific fibers, particularly concerning an individual's physiology, will offer the opportunity to exploit these functional characteristics to elicit specific, symptom-targeting effects or use fiber types as adjunctive therapies.

Role of particle size in modulating starch digestibility and textural properties in a rye bread model system

In cereal products, the use of flour containing clusters of intact cells has been indicated as a potential strategy to decrease starch digestion. Rye possesses more uniform and thicker cell walls than wheat but its protective effect against starch digestion has not been elucidated. In this study, rye flours with three different particle sizes, large (LF) (∼1700 μm), medium (MF) (∼1200 μm), and small (SF) (∼350 μm), were used to produce model bread. The textural properties of these breads were analysed using Textural Profile Analysis (TPA). The starch digestibility of both the flour and the bread was measured using Englyst's method, while the presence of intact cell clusters was examined using Confocal Laser Scanning Microscopy (CLSM). Additionally, the disintegration of bread digesta during simulated digestion was assessed through image analysis. CLSM micrographs revealed that bread made with MF and LF retained clusters of intact cells after processing, whereas bread made with SF showed damaged cell walls. Starch digestibility in LF and MF was lower (p ≤ 0.05) than that in SF. Bread produced with MF and LF exhibited the least (p ≤ 0.05) cohesive and resilient texture, disintegrated more during digestion, and exhibited higher starch digestibility (p ≤ 0.05) than bread made with SF. These results highlight the central role of bread texture on in vitro starch digestibility.

Exploring the cholesterol-lowering effects of cereal bran cell wall-enriched diets

Cell wall polysaccharides (dietary fiber) in cereal grains contribute to health benefits. The novelty of the current study was an effort to explore the in vivo therapeutic potential of different cereal bran cell walls against hypercholesterolemia. For this purpose, the cell walls were isolated from different cereal brans (wheat, maize, oats, and barley), and the intake of these cereal bran cell walls was evaluated for their anti-lipidemic activity in normal and hypercholesterolemic rats. The serum taken from the rats was tested for cholesterol, lipid, and triglyceride profiles before and after treatment. The outcomes of the current study have shown that the cereal cell wall has a significant hypercholesterolemia effect. The biochemical parameters of the control animals were within the normal clinical ranges, indicating that the experimental diets were safe. Among cereal bran cell walls, barley bran significantly decreased cholesterol (56.35 ± 1.35 mg/dL), low-density lipoprotein (56.35 ± 1.05 mg/dL), triglycerides (105.29 ± 1.95 mg/dL), and increased high-density lipoprotein level (48.35 ± 1.35 mg/dL). These findings provide conclusive evidence that the cereal cell wall is beneficial in the treatment of hypercholesterolemia and may potentially provide protection against other acute, recurring, or chronic illnesses.

Structural characteristics and biological activities of polysaccharides from barley: a review

Barley (Hordeum vulgare L.) is rich in starch and non-starch polysaccharides (NSPs), especially β-glucan and arabinoxylan. Genotypes and isolation methods may affect their structural characteristics, properties and biological activities. The structure-activity relationships of NSPs in barley have not been paid much attention. This review summarizes the extraction methods, structural characteristics and physicochemical properties of barley polysaccharides. Moreover, the roles of barley β-glucan and arabinoxylan in the immune system, glucose metabolism, regulation of lipid metabolism and absorption of mineral elements are summarized. This review may help in the development of functional products in barley.

Effect of chemical, thermal, and enzymatic processing of wheat bran on the solubilization, technological and biological properties of non-starch polysaccharides

Wheat bran is a low-cost by-product with significant nutritional value, but it is primarily utilized in animal feed applications. This study sought to investigate chemical methodologies for modifying the wheat bran's structure, enhancing non-starch polysaccharides solubility in water, and assessing alterations in functional and biological attributes. Chemical modifications were conducted under aqueous, alkaline, acid, and oxidizing conditions. Parameters such as yield, monosaccharides, arabinoxylans, β-glucan and phenolic content, molecular weight, functional properties, and prebiotic in vitro capacity were examined. The samples exhibited higher yields than the control, particularly in alkaline and acidic extractions. Notably, all soluble polysaccharide fractions (SPF) displayed a reduced molecular weight (<25KDa). β-glucan contents were raised in alkaline and acid extractions compared to the control, despite only in alkaline extraction were observed increase in arabinoxylans, confirmed by enzymatic-driven linkage analyses. Phenolic compounds and their antioxidant activities were low across all SPF. The samples showed heightened solubility, minimal foaming, and reduced water absorption properties. An alkaline extraction demonstrated a potential high prebiotic effect. Most samples showed positive relative growth and prebiotic activity for Lactobacillus and Bifidobacterium. This study suggests that an alkaline extraction of wheat by-product could enhance its value by increasing β-glucan content, arabinoxylans release, and prebiotic potential.

Integration of subcritical water extraction and treatment with xylanases and feruloyl esterases maximises release of feruloylated arabinoxylans from wheat bran

Wheat bran is an abundant and low valued agricultural feedstock rich in valuable biomolecules as arabinoxylans (AX) and ferulic acid with important functional and biological properties. An integrated bioprocess combining subcritical water extraction (SWE) and enzymatic treatments has been developed for maximised recovery of feruloylated arabinoxylans and oligosaccharides from wheat bran. A minimal enzymatic cocktail was developed combining one xylanase from different glycosyl hydrolase families and a feruloyl esterase. The incorporation of xylanolytic enzymes in the integrated SWE bioprocess increased the AX yields up to 75%, higher than traditional alkaline extraction, and SWE or enzymatic treatment alone. The process isolated AX with tailored molecular structures in terms of substitution, molar mass, and ferulic acid, which can be used for structural biomedical applications, food ingredients and prebiotics. This study demonstrates the use of hydrothermal and enzyme technologies for upcycling agricultural side streams into functional bioproducts, contributing to a circular food system.

Effects of starch hydration properties on the batter properties and oil absorption of fried crust and battered ham sausages

Water plays an important role in deep-frying. To assess the effects of water on oil absorption by fried crust and battered ham sausages (FCBHSs), we selected four starch types with different hydration properties: tapioca starch (TS), freeze-thawed tapioca starch (FTS), carboxymethyl tapioca starch (CMTS), and carboxymethyl freeze-thawed tapioca starch (CM-FTS). CMTS had the best hydration properties, followed by CM-FTS, FTS, and TS, respectively. CM-FTS with its medium hydration properties strengthened batter properties which reduced FCBHSs oil absorption. Low-field nuclear magnetic resonance analysis revealed that CM-FTS increased the percentages of bound and semi-bound water in the batter, thereby enhancing water retention and delaying water loss during deep-frying. Analyses of protein particle size distribution, zeta potential, disulfide bonding and microstructure revealed that CM-FTS promotes protein aggregation and the formation of a protein network structure, leading to a denser internal structure, which inhibits oil absorption. Additionally, differential scanning calorimetry analysis indicated that CM-FTS enhances the batter's thermal stability of batter, thereby rendering it more resistant to frying. However, the use of CMTS, with its strong hydration properties increased FCBHSs oil absorption. In conclusion, we propose that suitable modification of starch's hydration properties can aid in preparing deep-fried battered food characterized by low oil absorption.

The Influence of Biomolecule Composition on Colloidal Beer Structure

Recent studies have revealed an interest in the composition of beer biomolecules as a colloidal system and their influence on the formation of beer taste. The purpose of this research was to establish biochemical interactions between the biomolecules of plant-based raw materials of beer in order to understand the overall structure of beer as a complex system of bound biomolecules. Generally accepted methods of analytical research in the field of brewing, biochemistry and proteomics were used to solve the research objectives. The studies allowed us to establish the relationship between the grain and plant-based raw materials used, as well as the processing technologies and biomolecular profiles of beer. The qualitative profile of the distribution of protein compounds as a framework for the formation of a colloidal system and the role of carbohydrate dextrins and phenol compounds are given. This article provides information about the presence of biogenic compounds in the structure of beer that positively affect the functioning of the body. A critical assessment of the influence of some parameters on the completeness of beer taste by biomolecules is given. Conclusion: the conducted analytical studies allowed us to confirm the hypothesis about the nitrogen structure of beer and the relationship of other biomolecules with protein substances, and to identify the main factors affecting the distribution of biomolecules by fractions.

The Effect of the Addition of Fiber Preparations on the Color of Medium-Grounded Pasteurized and Sterilized Model Canned Meat Products

A beneficial aspect of the use of fiber preparations in the meat industry is the improvement of some quality characteristics of meat products. However, the preparation added in the amount of 3 or 6% may affect their color. The effect of the addition of barley, wheat and oat fiber preparations with different fiber lengths, in quantities allowing the product to be indicated as “high in fiber” or “source of fiber”, to pasteurized or sterilized medium-grounded canned meat products on their color, was determined. In the obtained canned meat products, the basic chemical composition and the L*, a* and b*, C* (Chroma) and h* (hue angle) color components were determined. The addition of the barley fiber preparation BG 300 to the model canned meat products caused a significant (p ≤ 0.05) darkening and an increase in the proportion of yellow color. In an industrial practice, this may result in poorer consumer acceptance of the meat product. Fiber length of wheat and barley fiber had no effect on the color components of products. The 6% addition of the wheat fiber preparations WF 200R and WF 600R or the oat fiber preparations HF 200 and HF 600 caused an apparent lightening of their color (ΔE > 2) compared to the control products.

Multimodularity of a GH10 Xylanase Found in the Termite Gut Metagenome

Xylan is the major hemicellulosic polysaccharide in cereals and contributes to the recalcitrance of the plant cell wall toward degradation. Bacteroidetes, one of the main phyla in rumen and human gut microbiota, have been shown to encode polysaccharide utilization loci dedicated to the degradation of xylan. Here, we present the biochemical characterization of a xylanase encoded by a bacteroidetes strain isolated from the termite gut metagenome.

The functional screening of a Pseudacanthotermes militaris termite gut metagenomic library revealed an array of xylan-degrading enzymes, including P. militaris 25 (Pm25), a multimodular glycoside hydrolase family 10 (GH10). Sequence analysis showed details of the unusual domain organization of this enzyme. It consists of one catalytic domain, which is intercalated by two carbohydrate binding modules (CBMs) from family 4. The genes upstream of the genes encoding Pm25 are susC-susD-unk, suggesting Pm25 is a Xyn10C-like enzyme belonging to a polysaccharide utilization locus. The majority of Xyn10C-like enzymes shared the same interrupted domain architecture and were vastly distributed in different xylan utilization loci found in gut Bacteroidetes, indicating the importance of this enzyme in glycan acquisition for gut microbiota. To understand its unusual multimodularity and the possible role of the CBMs, a detailed characterization of the full-length Pm25 and truncated variants was performed. Results revealed that the GH10 catalytic module is specific toward the hydrolysis of xylan. Ligand binding results indicate that the GH10 module and the CBMs act independently, whereas the tandem CBM4s act synergistically with each other and improve enzymatic activity when assayed on insoluble polysaccharides. In addition, we show that the UNK protein upstream of Pm25 is able to bind arabinoxylan. Altogether, these findings contribute to a better understanding of the potential role of Xyn10C-like proteins in xylan utilization systems of gut bacteria.

IMPORTANCE Xylan is the major hemicellulosic polysaccharide in cereals and contributes to the recalcitrance of the plant cell wall toward degradation. Members of the Bacteroidetes, one of the main phyla in rumen and human gut microbiota, have been shown to encode polysaccharide utilization loci dedicated to the degradation of xylan. Here, we present the biochemical characterization of a xylanase encoded by a Bacteroidetes strain isolated from the termite gut metagenome. This xylanase is a multimodular enzyme, the sequence of which is interrupted by the insertion of two CBMs from family 4. Our results show that this enzyme resembles homologues that were shown to be important for xylan degradation in rumen or human diet and show that the CBM insertion in the middle of the sequence seems to be a common feature in xylan utilization systems. This study shed light on our understanding of xylan degradation and plant cell wall deconstruction, which can be applied to several applications in food, feed, and bioeconomy.

Effect of thermal treatment on the physicochemical, ultrastructural and nutritional characteristics of whole grain highland barley

Highland barley (HB) was subjected to three thermal treatments (heat fluidization, microwave, and baking) and assessed for physicochemical, ultrastructural and nutritional properties. After thermal treatments, the hardness, bulk density, thousand kernel weight, length/breadth ratio, and color difference decreased significantly, while puffing index increased. Meanwhile, the formation of fissure was observed in the appearance. Microstructure images illustrated that numerous micropores were evenly distributed in the endosperm structure, and aleurone layer cells were deformed by compression. Furthermore, a dramatically disruption of endosperm cell walls and slightly deformation of outer layers were observed by confocal laser scanning microscopy. Moreover, a notably decrease in total phenolics (14.02%-36.91%), total flavonoids (25.28%-44.94%), and bound phenolics (8.99%-27.53%) was detected, while free phenolics (8.81%-43.40%), β-glucan extractability (4.71%-43.66%), antioxidant activity (71.87%-349.77%), and reducing power (3.05%-56.13%) increased significantly. Greatest increase in nutritional values was caused by heat fluidization, which possessed the potential for development of ready-to-eat functional foods.

Non-Starch Polysaccharides in Wheat Beers and Barley Malt beers: A Comparative Study

Non-starch polysaccharides (NSPs) in beers attract extensive attention due to their health benefits. The aim of this work was to investigate and compare NSPs including arabinoxylan, arabinogalactan, β–glucans, and mannose polymers in wheat and barley malt beers as well as the influence on its quality. NSPs in wheat beers (1953–2923 mg/L) were higher than that in barley malt beers (1442–1756 mg/L). Arabinoxylan was the most abundant followed by arabinogalactan. In contrast to barley malt beers, wheat beers contained more mannose polymers (130–182 mg/L) than β-glucan (26–99 mg/L), indicating that more arabinoxylan, arabinogalactan, and mannose polymers came from wheat malt. The substitution degree of arabinoxylan in wheat beers (0.57–0.66) was lower than that in barley malt beers (0.68–0.72), while the degree of polymerization (38–83) was higher (p < 0.05) than that in barley malt beers (38–48), indicating different structures of arabinoxylan derived from barley malt and wheat malt. NSPs, especially arabinoxylan content, positively correlated (p < 0.01) with real extract and viscosity of beers. Furthermore, wheat and barley malt beers were well separated in groups by principal component analysis.

The effect of different dietary levels of hybrid rye and xylanase addition on the performance and egg quality in laying hens

1. In this study, 240 ISA Brown hens were fed diets containing different levels of hybrid rye, and the influence of xylanase addition on laying performance and egg quality was evaluated. 2. Birds were allocated to 10 treatment groups with 12 replicates (cages) of two hens and were fed, from week 26 to 50, isocaloric and isonitrogenous experimental diets. A 5 × 2 experimental arrangement was applied, using diets with increasing level of rye (0%, 10%, 15%, 20% or 25%) with or without xylanase supplementation (200 mg/kg of feed; Ronozyme WX (CT) with minimum xylanase activity of 1,000 FXU/g). 3. Increasing dietary level of rye did not affect daily mass of eggs, mean egg weight or feed conversion ratio (P > 0.05). Laying rate decreased in all groups fed with rye. Egg and eggshell quality indices were unaffected by dietary rye grain (P > 0.05); however, rye inclusion significantly decreased yolk colour on the DSM scale (P < 0.05). In comparison with the control group, high dietary levels of rye (25%) significantly increased viscosity of small intestine content (P < 0.05). Diet supplementation with xylanase had no significant effect on egg production indices and egg quality (except for yolk colour) but decreased the viscosity of intestinal content in laying hens fed high levels of rye (P < 0.05). 4. The results of this experiment suggest that rye may be incorporated to a level of 25% in the diet of laying hens without any strong negative effect on egg performance, while xylanase added to high-rye grain reduced the viscosity of intestinal content; however, it did not positively affect the laying performance or egg quality.

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. For each of wheat, rye, and hull-less barley, soluble and insoluble fibre fractions from refined flour and models for baking and extrusion had comparable in vitro fermentation rates and extents, with similar levels of short chain fatty acid metabolites. This study suggests that there should be little difference in the large intestinal nutritional functionality of the soluble and insoluble fibre fractions from cereal grain flours, either unprocessed or after baking or extrusion processing.

Structural Variation and Content of Arabinoxylans in Endosperm and Bran of Durum Wheat (Triticum turgidum L.)

Arabinoxylans are one group of dietary fiber components in cereal grains, and specific health benefits have been linked with their molecular fine structures and hence with physicochemical properties such as solubility in aqueous media. To characterize the fiber quality for functional foods, starchy endosperm and bran fractions from 11 durum wheat lines were analyzed for total and water-soluble arabinoxylans, (1,3;1,4)-β-glucan, and bound ferulic acid. The arabinoxylan contents ranged from 11 to 16.4% (w/w) in bran and from 1.5 to 1.8% in the starchy endosperm. Of the starchy endosperm arabinoxylans, 37% was soluble in water. No correlation was found between arabinoxylan content and bound ferulic acid in bran, although a relatively high level of this antioxidant was found in endosperm (38.3 μg/g endosperm flour). Enzymatic fingerprinting was performed to define the major fine structural features of arabinoxylans from both regions of the grain. Five major oligosaccharides released by xylanase hydrolysis were identified and characterized in the 11 durum lines. In addition, DP5, DP6, and DP7 oligosaccharides containing five, six, and seven pentosyl residues, respectively, were purified.

Studies on the Simultaneous Formation of Aroma-Active and Toxicologically Relevant Vinyl Aromatics from Free Phenolic Acids during Wheat Beer Brewing

During the brewing process of wheat beer, the desired aroma-active vinyl aromatics 2-methoxy-4-vinylphenol and 4-vinylphenol as well as the undesired and toxicologically relevant styrene are formed from their respective precursors, free ferulic acid, p-coumaric acid, and cinnamic acid, deriving from the malts. Analysis of eight commercial wheat beers revealed high concentrations of 2-methoxy-4-vinylphenol and 4-vinylphenol always in parallel with high concentrations of styrene or low concentrations of the odorants in parallel with low styrene concentrations, suggesting a similar pathway. To better understand the formation of these vinyl aromatics, each process step of wheat beer brewing and the use of different strains of Saccharomyces cerevisiae were evaluated. During wort boiling, only a moderate decarboxylation of free phenolic acids and formation of desired and undesired vinyl aromatics were monitored due to the thermal treatment. In contrast, this reaction mainly occurred enzymatically catalyzed during fermentation with S. cerevisiae strain W68 with normal Pof(+) activity (phenolic off-flavor) resulting in a wheat beer eliciting the typical aroma requested by consumers due to high concentrations of 2-methoxy-4-vinylphenol (1790 μg/L) and 4-vinylphenol (937 μg/L). Unfortunately, also a high concentration of undesired styrene (28.3 μg/L) was observed. Using a special S. cerevisiae strain without Pof(+) activity resulted in a significant styrene reduction (<LoQ), but also in low amounts of 2-methoxy-4-vinylphenol (158 μg/L) and 4-vinylphenol (46.7 μg/L), resulting in a less pronounced wheat beer aroma.