Effect of soluble polysaccharides addition on rheological properties and microstructure of chitin nanocrystal aqueous dispersions

Chitin nanocrystals as natural gel modifier for yielding stronger acid-induced soy protein isolate gel

This study aimed to enhance the rheological properties and thermal stability of acid-induced soy protein isolate (SPI) gels by incorporating chitin nanocrystals (ChNCs) and proposing a gelation mechanism. SPI gels exhibited pseudo-plastic behavior. Increasing ChNCs concentration from 0.00 % to 1.00 % improved G' values, recovery rate, and initial degradation temperature: from 75.6 Pa to 1024.3 Pa, 80.27 % to 85.47 %, and 261.5 °C to 275.8 °C, respectively. FTIR analysis confirmed electrostatic and hydrogen bonding interactions between SPI and ChNCs. Adding 1.00 % ChNCs reduced α-helix content from 19.7 % to 12.1 % while increasing β-sheet content from 46.5 % to 52.6 %. This led to protein unfolding, exposure of Trp residues, and orderly aggregation, forming a dense cross-linked gel network. Gel particle size increased from 185.5 nm (no ChNCs) to 504.4 nm (1.00 % ChNCs), with reduced surface charges. Hydrophobic and electrostatic interactions were key forces stabilizing SPI-ChNCs gels. These findings offer a practical approach to enhancing traditional acid-induced protein gel-based functional foods using naturally sourced chitin nanocrystals.

Preparation and characterisation of linalool oil-in-water starch-based Pickering emulsions and the effects of the addition of cellulose nanocrystals on their stability

Creaming could be generated during storage of the starch-based Pickering emulsions. And cellulose nanocrystals in the solution are usually dispersed by relatively strong mechanical force, otherwise they may appear in the form of aggregates. In this work, we investigated the effects of cellulose nanocrystals on the stability of the starch-based Pickering emulsions. Results showed that the stability of Pickering emulsions was significantly improved by adding cellulose nanocrystals. Cellulose nanocrystals increased the viscosity, electrostatic repulsion and steric hindrance of the emulsions, which delayed the movement of droplets and obstructed the contact between droplets. This study provides new insights into the preparation and stabilisation of starch-based Pickering emulsions.

Pickering emulsion stabilized by composite-modified waxy corn starch particles

The starch-based Pickering stabilizer has attracted more research interest recently, however, its application in food system is limited due to the low digestibility of raw starch particles. In this study, waxy corn starches were modified with octenyl succinic anhydride and then treated by dry heating at 180 °C for 20-60 min. Pickering emulsions stabilized by the composite-modified starch particles were fabricated, the physical stability, rheology property and microstructure of the emulsions were investigated. The results showed that the composite-modified starches maintained granule structure, their gelatinization temperatures and enthalpy significantly reduced after heat treatment (p < 0.05). Compared with native starch, the composite-modified starches had bigger three-phase contact angles and higher in vitro digestibility, while the relative crystallinity decreased from 32.46% to 24.87%. Pickering emulsions stabilized by composite-modified starch particles had long-term stability up to 300 days. The rheology results showed that all emulsions exhibited pseudoplastic behaviors and had higher storage modulus than loss modulus. Moreover, the viscosities decreased when the starch was roasted for 40 and 60 min. The composite-modified starch particles and few starch macromolecules at oil-water interface stabilized the emulsions collectively. These results provide a new strategy for designing an edible Pickering stabilizer.

WITHDRAWN: Reinforcing the rheological and mechanical properties of WPI nanocomposite hydrogels with birefringence morphologies

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Liquid crystalline and rheological properties of chitin whiskers with different chemical structures and chargeability

The liquid crystalline and rheological properties of chitin whiskers (CHWs) are significant for their application in fabrication of highly ordered composite materials and optical components. The aim of this work was to elucidate the influence of chemical structure and chargeability (zeta potential, electropositivity, electronegativity or zwitterionic character) on the liquid crystalline and rheological properties of CHWs. Firstly, CHWs with different chemical structure, including positively charged whiskers (CHWs and CHWs-D/60 min) and negatively charged whiskers (mCHWs), were designed via acid hydrolysis, deacetylation, and maleation, respectively. Subsequently, the chargeability of the above whiskers was further regulated by protonation or deprotonation. The whisker aqueous suspensions with high zeta potential behaved as nematic liquid crystals or chiral nematic liquid crystals, whereas those with low zeta potential had no liquid crystal characteristics. The viscosity, G', and G" values of the CHWs and CHWs-D/60 min aqueous suspensions treated with protonation were lower than those of the corresponding whiskers treated with deprotonation. However, the mCHWs exhibited different changes in their rheological properties under protonation or deprotonation due to the electronegativity and zwitterionic characteristics. In addition, the effects of ionic strength and pH on the liquid crystalline and rheological properties of CHWs, CHWs-D/60 min, and mCHWs aqueous suspensions varied since the chemical structure and chargeability of whiskers differ.

Macromolecular properties and hypolipidemic effects of four sulfated polysaccharides from sea cucumbers

The present study investigates the relationship between the high-order structure and hypolipidemic activity of four well-defined sulfated fucans from sea cucumber. The chain conformation, determined by a combination of AFM and SEC-MALLS-RI, indicate that fucosylated chondroitin sulfate (fCS) from Pearsonothuria graeffei (fCS-Pg) and Isostichopus badionotus (fCS-Ib), and fucoidan from P.graeffei (fuc-Pg) were assigned as a random coil conformation with polysaccharide chain outstretched, while I. badionotus (fuc-Ib) was assigned as a spherical conformation and exhibited high viscosity. Fuc-Pg and fuc-Ib with higher molecular weights had a greater impact in inhibiting pancreatic lipase activity in vitro. However, fCS-Pg, fCS-Ib and fuc-Pg with random linear conformation exhibited excellent hypolipidemic activity in Sprague-Dawley rats (SD rats) fed on high-fat diet (HFD), whereas fuc-Ib showed only a modest effect. Our results indicate that structural characteristics, including side branch and sulfation pattern can affect the chain conformation of polysaccharides, which determine their physicochemical properties and hypolipidemic activity.

Housing tubes from the marine worm Chaetopterus sp.: biomaterials with exceptionally broad thermomechanical properties

The housing tube material of the marine worm Chaetopterus sp. exhibits thermal stability up to 250°C, similar to other biological materials such as mulberry silkworm cocoons. Interestingly, however, dynamic mechanical thermal analysis conducted in both air and water elucidated the lack of a glass transition in the organic tube wall material. In fact, the viscoelastic properties of the anhydrous and undried tube were remarkably stable (i.e. constant and reversible) between -75°C and 200°C in air, and 5°C and 75°C in water, respectively. Moreover, it was found that hydration and associated-water plasticization were key to the rubber-like flexible properties of the tube; dehydration transformed the material behaviour to glass-like. The tube is made of bionanocomposite fibrils in highly oriented arrangement, which we argue favours the biomaterial to be highly crystalline or cross-linked, with extensive hydrogen and/or covalent bonds. Mechanical property characterization in the longitudinal and transverse directions ascertained that the tubes were not quasi-isotropic structures. In general, the higher stiffness and strength in the transverse direction implied that there were more nanofibrils orientated at ± 45° and ± 65° than at 0° to the tube axis. The order of the mechanical properties of the soft-tough tubes was similar to synthetic rubber-like elastomers and even some viscid silks. The complex structure-property relations observed indicated that the worm has evolved to produce a tubular housing structure which can (i) function stably over a broad range of temperatures, (ii) endure mechanical stresses from specific planes/axes, and (iii) facilitate rapid growth or repair.

Chitin hybrid materials reinforced with graphene oxide nanosheets: chemical and mechanical characterisation

A novel hybrid material of chitin–nGO was obtained. nGO reinforces the material by rearrangement of chitin chains, improving its chemical and mechanical properties.

Soluble chitosan-carrageenan polyelectrolyte complexes and their gastroprotective activity

The soluble polyelectrolyte complexes (PEC) κ-carrageenan (κ-CG):chitosan was obtained. Binding constant value (2.11 × 10(7)mol(-1)) showed high affinity of κ-CG to chitosan. The complex formation of κ-CG:chitosan 1:10 and 10:1 w/w was shown by centrifugation in a Percoll gradient. Using atomic force microscopy we showed that the supramolecular structure of the complexes is different from each other and from the macromolecular structure of the initial polysaccharides. The gastroprotective and anti-ulcerogenic effect of κ-CG, chitosan and their complexes was investigated on the model of stomach ulcers induced by indometacin in rats. PEC κ-CG:chitosan have gastroprotective properties which depend on their composition. Complex κ-CG:chitosan 1:10 w/w possesses higher gastroprotective activity than the complex 10:1 w/w. These results suggest that the gastroprotective effect of complexes can be associated with their protective layer on the surface of the mucous membrane of a stomach, which avoids a direct contact with the ulcerogenic agent.