Microstructure and mechanical properties of arabinoxylan and (1,3;1,4)-β-glucan gels produced by cryo-gelation

Hydration and mechanical properties of arabinoxylan, (1,3;1,4)-β-glucan, and cellulose multilayer films simulating the cell wall of wheat endosperm

The cell walls of wheat endosperm, which play a pivotal role in seed germination, exhibit a laminated structure primarily composed of polysaccharides. In this study, composite multilayer films were prepared using arabinoxylan (AX), (1,3;1,4)-β-D-glucan (MLG), and cellulose nanofibers (CNFs), and the effect of polymer blend structure on cell wall hydration and mechanical properties was investigated. Atomic force microscopy and X-ray diffraction indicated that the network structure of MLG/CNF exhibits a higher degree of continuity and uniformity compared to that of AX/CNF. Mechanically, the extensive linkages between MLG and CNFs chains enhance the mechanical properties of the films. Moreover, water diffusion experiments and TD-NMR analysis revealed that water molecules diffuse faster in the network structure formed by AX. We propose a structural model of the endosperm cell wall, in which the CNFs polymer blend coated with MLG serves as the framework, and the AX network fills the gaps between them, providing diffusion channels for water molecules.

Effect of compositions and physical properties on 3D printability of gels from selected commercial edible insects: Role of protein and chitin

Compositions and rheological properties of alternative protein sources, including honey bee pupa, grasshopper, cricket, earthworm, and scorpion, and their relationships with 3D printing behaviors were investigated. Protein was found to be the major composition in all insects, while chitin exhibited the most variation. At optimal moisture contents, honey bee pupa and earthworm gels displayed sufficient fluidity but resulted in unstable printed structures, as observed visually and microstructurally. Grasshopper and scorpion gels possessed weak fluidity but produced more stable printed structures. Cricket gel exhibited the most balanced flow behavior and self-supportability. Protein-to-chitin mass ratio proved to be a main factor affecting the 3D printing behavior of the gels. Possible mechanisms on how compositions and properties affected the printing behavior of the gels were proposed. Suggestions for improving the 3D printability of insect and invertebrate resembling insect gels were provided based on these proposed mechanisms.

A comparison between partially peeled hulless barley and whole grain hulless barley: beneficial effects on the regulation of serum glucose and the gut microbiota in high-fat diet-induced obese mice

Though the hypoglycemic effect of whole grain hulless barley (Hordeum vulgare L.) has been documented, whether glucose metabolism would be improved by hulless barley with moderate peeling is still unclear. The purpose of this study was to compare the differences in glucose metabolism and gut microbiota between partially (10%) peeled hulless barley (PHB) and whole grain hulless barley (WHB) intervention in obese mice induced by a high-fat diet. The results showed that both PHB and WHB interventions significantly improved the impaired glucose tolerance, fat accumulation in fat and liver tissues, and the impaired intestinal barrier in mice. The dysbiosis of gut microbiota was improved and the relative abundance of some beneficial bacteria such as genera Lactobacillus, Bifidobacterium, Ileibacterium, and norank_f__Mutibaculaceae was increased by both, PHB and WHB, interventions. Spearman correlation analysis revealed that the abundance of Bifidobacterium was negatively correlated with the area under the blood glucose curve. In conclusion, our results provide evidence that hulless barley improved the gut microbiota and impaired glucose tolerance in mice, and also showed that there was little loss of hypoglycemic effect even when hulless barley was moderately peeled.

Recent advances of cereal β-glucan on immunity with gut microbiota regulation functions and its intelligent gelling application

β-glucan from cereals such as wheat, barley, oats and rye are a water-soluble dietary fiber, which are composed of repeating (1→4)-β-bond β-D-glucopyranosyl units and a single (1→3)-β-D-bond separated unit. β-glucan has a series of physicochemical properties (such as viscosity, gelling properties, solubility, etc.), which can be used as a food gel and fat substitute. Its structure endows the healthy functions, including anti-oxidative stress, lowering blood glucose and serum cholesterol, regulating metabolic syndrome and exerting gut immunity via gut microbiota. Due to their unique structural properties and efficacy, cereal β-glucan are not only applied in food substrates in the food industry, but also in food coatings and packaging. This article reviewed the applications of cereal β-glucan in hydrogels, aerogels, intelligent packaging systems and targeted delivery carriers in recent years. Cereal β-glucan in edible film and gel packaging applications are becoming more diversified and intelligent in recent years. Those advances provide a potential solution based on cereal β-glucan as biodegradable substances for immune regulation delivery system and intelligent gelling material in the biomedicine field.

Preparation and characterisation of a novel hydrogel based on Auricularia polytricha β-glucan and its bio-release property for vitamin B12 delivery

BACKGROUND

This study investigates a novel hydrogel synthesis method and its bio-release property. This hydrogel, with a three-dimensional network structure based on Auricularia polytricha β-glucan, was characterised by means of Fourier transform infrared spectroscopy, ¹ H NMR and scanning electron microscopy. Vitamin B₁₂ (VB₁₂ , cobalamin) as a hydrophilic functional food component was entrapped into these hydrogels. The in vitro release profile of VB₁₂ was established in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF).

RESULTS

The results showed that the hydrogel had medium pore size from 30 to 300 µm, and the swelling ratio increased with the degree of substitution. The hydrogel demonstrated good stability in SGF and bio-release capability in SIF for VB₁₂ . The accumulated release rate is about 80% in SIF and below 20% in SGF, which indicated the significant different release property in stomach and intestine.

CONCLUSION

The Auricularia polytricha β-glucan-based hydrogel has a good swelling ratio, pepsin stability and pancrelipase-catalysed biodegradation property. The bio-release rate is significantly different in SIF and SGF, which indicated that this hydrogel could be a good intestinal target carrier of VB₁₂ . © 2017 Society of Chemical Industry.

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

Recent studies show that a single or small number of intestinal microbes can completely degrade complex carbohydrates. This suggests a drive towards competitive utilisation of dietary complex carbohydrates resulting in limited microbial diversity, at odds with the health benefits associated with a diverse microbiome. This study investigates the enzymatic metabolism of wheat and rye arabinoxylans (AX) using in vitro fermentation, with a porcine faecal inoculum. Through studying the activity of AX-degrading enzymes and the structural changes of residual AX during fermentation, we show that the AX-degrading enzymes are mainly cell-associated, which enables the microbes to utilise the AX competitively. However, potential for cross-feeding is also demonstrated to occur by two distinct mechanisms: (1) release of AX after partial degradation by cell-associated enzymes, and (2) release of enzymes during biomass turnover, indicative of co-operative AX degradation. This study provides a model for the combined competitive-co-operative utilisation of complex dietary carbohydrates by gut microorganisms.

Emerging models on the regulation of intercellular transport by plasmodesmata-associated callose

The intercellular transport of molecules through membranous channels that traverse the cell walls-so-called plasmodesmata-is of fundamental importance for plant development. Regulation of plasmodesmata aperture (and transport capacity) is mediated by changes in the flanking cell walls, mainly via the synthesis/degradation (turnover) of the (1,3)-β-glucan polymer callose. The role of callose in organ development and in plant environmental responses is well recognized, but detailed understanding of the mechanisms regulating its accumulation and its effects on the structure and permeability of the channels is still missing. We compiled information on the molecular components and signalling pathways involved in callose turnover at plasmodesmata and, more generally, on the structural and mechanical properties of (1,3)-β-glucan polymers in cell walls. Based on this revision, we propose models integrating callose, cell walls, and the regulation of plasmodesmata structure and intercellular communication. We also highlight new tools and interdisciplinary approaches that can be applied to gain further insight into the effects of modifying callose in cell walls and its consequences for intercellular signalling.