Evaluation of the composition of konjac glucomannan on the color changes during the deacetylation reaction

Physicochemical and rheological properties of konjac glucomannan and its mixed gels with κ-carrageenan: Effect of deacetylation by L-arginine

Konjac glucomannan (KGM) is a natural functional polysaccharide, and deacetylation (removing acetyl groups) impacts its physicochemical and gel properties. In order to study KGM's gel properties and explore new deacetylation modifiers, three deacetylated konjac glucomannan (DKGM) with different deacetylation degrees (DD, 17.51 %, 35.41 %, and 54.52 %) were prepared using L-arginine. Results showed that L-arginine deacetylated and retained the main structure and high molecular weight of KGM. Solubility decreased from 85.38 % to 81.17 %, transparency decreased from 38.52 % to 35.73 %, water absorbing and swelling slowed down, and molecular morphology changed from chain structures to micelle-like aggregates after deacetylation. Dynamic viscoelastic analysis showed that deacetylation facilitated the formation of the entangled network structure of KGM. The strength of konjac glucomannan and κ-carrageenan mixed gels increased after deacetylation, and this enhancement was mainly through hydrogen bonds and hydrophobic interactions. These findings will provide theoretical guidance for the application of KGM.

Sustainable management of mixed soil contaminants through integrated biosystems: Efficacy of biochar and humic acid amendments in marigold phytoremediation

A study investigated the fate and transport of mixed contaminants-chromium (Cr), cadmium (Cd), and perfluorooctanoic acid (PFOA)-in soil using an integrated biosystem. Known concentrations of contaminants and organic amendments (biochar and humic acid) were introduced into unpolluted soil to assess degradability, mobility, bioavailability, and phytoremediation potential using marigold plants. Contaminants reduced plant physiological traits, including photosynthetic rate (33%), stomatal conductance (58%), and transpiration rate (74%) compared to control plants. Root traits and the effectiveness of biochar and humic acid were evaluated using "GiA Roots" software. Root architecture varied significantly due to contamination, with seven traits analyzed through principal component analysis (PCA). PC1 accounted for 79% variance, highlighting amendment effects, while PC2 (21%) grouped mixed contaminant treatments, indicating that biochar and humic acid enhanced root growth in contaminated soil. Additionally, untreated contaminated soil produced the root growth inhibitor 2-methyl cortisol, identified via GC/MS analysis. Scanning electron microscope analysis showed that roots in control soil had well-defined stele structures, whereas contaminated soil led to severe structural collapse. Post-harvest soil analysis revealed that humic acid treatments reduced Cr, Cd, and PFOA by 48.5%, 40.1%, and 88%, respectively, while biochar treatments achieved reductions of 68.3%, 52.7%, and 92%. These results highlight the effectiveness of biochar and humic acid in reducing contamination through sorptive properties and chemical binding. Applying biochar at 5 t ha⁻1 or humic acid at 20 kg ha⁻1, combined with phytoremediation, effectively mitigated soil toxicity, improving crop productivity by lowering contaminant levels.

Use of ozone oxidation in combination with deacetylation for improving the structure and gelation properties of konjac glucomannan

In this study, oxidized deacetylated konjac glucomannans with different degrees of oxidation were prepared by a combination of deacetylation and ozone oxidation. Carboxyl groups were found to be introduced into the modified konjac glucomannan while acetyl groups were removed. The backbone, branched chains, and crystal structure of modified konjac glucomannan were not significantly affected. The whiteness was enhanced to 97-99 % and the thermal degradation temperature was up to 250 °C after modification. The solubility of the modified konjac glucomannan (oxidized for 60 min) was significantly increased to 84.56 % (p < 0.05), while its viscosity and swelling power were notably decreased owing to the changes in molecular weight (from 106 to 104) and functional groups. Rheological analysis showed that oxidized deacetylated konjac glucomannan has the ability to form soft-textured gels and the potential to develop dysphagia foods. Future studies should focus on the gelation mechanisms of oxidized deacetylated konjac glucomannan.

Effect of pretreatment with electron beam irradiation on the deacetylation efficiency of konjac glucomannan and its structural, physicochemical and gel properties

Due to its emulsifying and thickening properties, konjac glucomannan (KGM) is widely used in the food, medicine, and materials industries. Nevertheless, its high viscosity and significant water absorption limit its application range. Therefore, electron beam (e-beam) irradiation pretreatment was carried out to improve the deacetylation efficiency of KGM, and the physicochemical and gel properties of KGM were investigated. The results show that e-beam irradiation and deacetylation decrease the water absorption, solubility, transparency, molecular weight, and viscosity of KGM. Conversely, the moisture content, thermal stability, and water-binding capacity increase. FTIR and X-ray diffraction analysis revealed no significant changes in the chemical and crystalline structure of KGM before and after modification. However, modification weakens the intermolecular interaction of KGM hydrosols, which affects their rheology. Furthermore, deacetylation improves the mechanical properties and water retention capacity of KGM gels. Overall, the e-beam irradiation pretreatment provides a method to increase the efficiency of KGM deacetylation and improve the physical and chemical properties of KGM, thus expanding its potential applications in the food and chemical industries, among others.

The synergetic effect of alginate-derived hydrogels and metal-phenolic nanospheres for chronic wound therapy

Management of diabetic wounds presents a global health challenge due to elevated levels of ROS in the wound microenvironment, persistent dysregulation of inflammation modulation, and limitations in commercially available dressings. Addressing this issue, we have developed a pH-responsive and glucose-sensitive multifunctional hydrogel dressing that dynamically responds to the wound microenvironment and enables on-demand drug release. The dressing incorporates a matrix material based on aminophenylboronic acid-functionalized alginate and a polyhydroxy polymer, alongside an enhancer phase consisting of self-assembled metal-phenol coordination nanospheres formed by tannic acid and iron ions. Using the dynamic borate ester bonds and catechol-metal ion coordination bonds, the dressing exhibits remarkable shape adaptability, self-healing capability, tissue adhesiveness, antioxidant activity, and photothermal responsiveness, without additional curatives or crosslinking agents. As a wound dressing, it elicits macrophage polarization towards an anti-inflammatory phenotype while maintaining long-lasting antimicrobial effects. In a diabetic mouse model of full-thickness wound infections, it effectively mitigated inflammation and vascular damage, significantly expediting the wound healing process with a commendable 97.7% wound closure rate. This work provides a new direction for developing multifunctional smart hydrogel dressings that can accelerate diabetic wound healing for human health.

Konjac glucomannan/carboxymethyl chitosan film embedding gliadin/casein nanoparticles for grape preservation

Constructing biopolymer-based packaging films with fantastic water resistance and mechanical properties for food preservation is highly desirable and challenging. In this work, Gliadin/Casein nanoparticles (GCNPs) were prepared by pH-driven method and embedded into konjac glucomannan/carboxymethyl chitosan (KC) film matrix to improve the water resistance and mechanical properties of KC film. Gliadin and Casein showed good compatibility and co-assembled to form compact GCNPs clusters through hydrogen bonding and hydrophobic interaction verified by FT-IR spectroscopy, and fluorescence spectroscopy. The particle size and zeta potential of GCNPs was 269.7 nm and -7.6 mV, respectively. The effect of GCNPs on the mechanics, water barrier, thermal stability, and UV-shielding of KC-GCNPs film was investigated. SEM images revealed that GCNPs uniformly distributed into KC film matrix and significantly improved the mechanics (tensile strength: 75.6 MPa, elongation at breaking: 36.7 %), water barrier ability (water contact angle: 91.3°, water vapor permeability: 0.994 g mm/m2 day kPa, water solubility: 52.0 %), thermal stability and UV blocking property of KC-GCNPs film. Furthermore, KC-GCNPs film could also be applied to extend the shelf life of grapes. This paper demonstrated the great potential of GCNPs as functional nanofillers in enhancing the physicochemical properties of KC film.