Polysaccharide solutions and gels: Isothermal dehydration study by dynamic calorimetric experiments with DSC

Controlled hydrolysis and EGCG conjugation enhance the ADH/ALDH activation activity of chia seed meal protein hydrolysates: Fabrication and structural characterization

This study examines the effects of hydrolysis duration (20-100 min using flavourzyme) and EGCG conjugation on the structure and bioactivity of chia seed meal protein hydrolysates (CSPH) through multi-spectroscopic techniques and physicochemical property evaluation. Subsequently, the activation effects of EGCG-conjugated peptides on alcohol metabolism-related enzymes were further analyzed through the integration of peptidomics, bioinformatics, and computational chemistry. It was found that with the extension of hydrolysis time, the thermal stability of CSPH diminishes, its rigid structure becomes more flexible, and its crystallinity decreases (by up to 27.19 %). Meanwhile, the activation effects on alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activity were significantly enhanced (P < 0.05). CSPH hydrolyzed for 60 min demonstrated the highest binding affinity for EGCG, primarily driven by hydrophobic interactions and hydrogen bonds. The CSPH-EGCG conjugate exhibited enhanced physicochemical properties and significantly elevated activation of ADH and ALDH, with ADH activation rising from 22.66 % to 95.56 % and ALDH activation from 9.45 % to 30.93 %, compared to unmodified CSPH. Seven active peptides were identified from PE-60 by peptidomics and bioinformatics. Computer docking optimized selected three optimal peptides (IPW, FPIH, and IYP). Two-dimensional and three-dimensional interaction analyses showed that these peptides bind to EGCG, ADH, and ALDH via hydrogen bonds, hydrophobic interactions, and salt bridges. These findings highlight the potential of controlled hydrolysis with flavourzyme and EGCG incorporation to enhance CSPH's properties and bioactivities and offer insights into the practical applications of CSPH and its EGCG complexes in food processing and therapeutic systems.

Insights into structure-antioxidant activity relationships of polyphenol-phospholipid complexes: The effect of hydrogen bonds formed by phenolic hydroxyl groups

Five typical polyphenols (catechin, quercetin, gallic acid, ellagic acid, and chlorogenic acid) were selected to form non-covalent complexes with soy lecithin, confirmed by 1H NMR, X-ray, DSC, and molecular docking simulations. Subsequently, the impacts of complexation on the antioxidant activity were evaluated using five different methods to analyze structure-activity relationships. The results showed that the complexation with phospholipids would not reduce the antioxidant activity of polyphenols, mainly attributed to three mechanisms: (i) the amphiphilic nature of phospholipids enhanced polyphenol solubility via encapsulation and amorphous state stabilization, (ii) hydrogen-bond networks immobilized reactive hydroxyl groups while shielding them from oxidative environments, and (iii) phospholipid-mediated kinetic solvent effects reduced the bond dissociation energy and optimized sustained antioxidant release kinetics. This study provides deeper insights into the interaction mechanisms between polyphenols and phospholipids and supports wider potential applications of polyphenols.

PEG-based-ultrasound-microwave synergistic extraction of mucilage polysaccharides from chia seed: Structural characterization and bioactivity

In this study, the effects of microwave, ultrasound, ultrasound-microwave synergy, and polyethylene glycol (PEG)-200 on the chia seed mucilage's (CSM) structural, thermal, and functional properties have been evaluated by modern spectroscopic techniques, crystal diffraction, and thermal analyses. The results showed that CSM, extracted by PEG-200 aqueous solution has the largest particles (1120-1231 μm), and the smallest size (44.06-317.19 μm) has been observed in microwave extraction. Furthermore, microwave exposure seems to impact the primary structure of CSM profoundly, evidenced by shifts and changes in spectroscopy under high-frequency microwave conditions. However, the incorporation of ultrasound significantly mitigates microwave's effect on the particle size, structural characteristics, coloration, and thermal stability of CSM. Interestingly, the exclusive use of PEG-200 in extraction results in a notably decreased absorption at 280 nm in the UV-vis spectrum, suggesting the near-complete exclusion of nucleic acids and proteins. CSM extracted by PEG-200 aqueous solution exhibits the highest enthalpy value (199.960 ± 2.920 J/g), glass transition temperature (200.449 ± 1.118 °C), the most abundant monosaccharide composition, and the highest molecular weight (3,456,558 Da), far exceeding the reported values in literature. In vitro bioactivity demonstrates that CSM extracted through the synergistic use of ultrasound and microwave exhibits the strongest DPPH and ABTS radical scavenging abilities, while CSM extracted with PEG-200 performs exceptionally well in iron ion chelating capacity. This study introduces a novel approach to CSM extraction by innovatively employing the green solvent PEG-200 and broadening the application of ultrasound-microwave synergistic technology in the extraction of plant polysaccharides.

Comparison of extraction process, physicochemical properties, and in vitro digestion characteristics of chia seed mucilage polysaccharide

The study explored five (acidic, alkaline, heating, ionic liquid, and urea solvent) extraction methods' effects on chia seed mucilage polysaccharide (CSM), an anionic polymeric macromolecule, regarding its physicochemical properties, structure, and digestion behavior. The results showed that extraction parameters have a considerable effect on modulating CSM properties. Significant differences emerged in the predominant chemical compositions: the carbohydrates and protein content ranged from 49.20±0.06 % to 85.81±0.03 %, and 3.20±0.13 % to 14.57±0.30 %, respectively. The structural analysis revealed that alkaline heating treatment facilitated the formation of protein-polysaccharide conjugates, resulting in reduced particle size, enhanced ζ-potential, and improved thermal stability (194.72±2.19 J/g). The crystallinity of CSM varied, peaking at 42.9±0.22 % without pH adjustment and heating. CSM extracted using 6 M urea exhibited the lowest protein content, and crystallinity (25.50±0.09 %), coupled with the highest gastrointestinal digestion rate and poorest thermal stability (with a carbohydrate degradability of 24.223±1.78 % and enthalpy value of 62.82±0.32 J/g). The CSM obtained under alkaline heating showed minute particles (201.1±10.35 μm), the highest ζ-potential absolute value (20.95±2.28 mV), and robust thermal stability (194.72±2.19 J/g of enthalpy value), which is ideal for stabilizing emulsions or encapsulating thermolabile substances. Additionally, compared to monovalent cations‑sodium ions, divalent cations‑magnesium ions, is more tend to aggregate the CSM structure, resulting in larger molecular particles and a higher protein content. Elevated ionic concentration further diminished thermal stability. These findings suggest that CSM is a customizable, multi-purpose polymer that can be extracted in various ways based on the end-product requirements.

Physicochemical and Rheological Properties of Succinoglycan Overproduced by Sinorhizobium meliloti 1021 Mutant

Commercial bacterial exopolysaccharide (EPS) applications have been gaining interest; therefore, strains that provide higher yields are required for industrial-scale processes. Succinoglycan (SG) is a type of bacterial anionic exopolysaccharide produced by Rhizobium, Agrobacterium, and other soil bacterial species. SG has been widely used as a pharmaceutical, cosmetic, and food additive based on its properties as a thickener, texture enhancer, emulsifier, stabilizer, and gelling agent. An SG-overproducing mutant strain (SMC1) was developed from Sinorhizobium meliloti 1021 through N-methyl-N'-nitro-N-nitrosoguanidine (NTG) mutation, and the physicochemical and rheological properties of SMC1-SG were analyzed. SMC1 produced (22.3 g/L) 3.65-fold more SG than did the wild type. Succinoglycan (SMC1-SG) overproduced by SMC1 was structurally characterized by FT-IR and 1H NMR spectroscopy. The molecular weights of SG and SMC1-SG were 4.20 × 105 and 4.80 × 105 Da, respectively, as determined by GPC. Based on DSC and TGA, SMC1-SG exhibited a higher endothermic peak (90.9 °C) than that of SG (77.2 °C). Storage modulus (G') and loss modulus (G″) measurements during heating and cooling showed that SMC1-SG had improved thermal behavior compared to that of SG, with intersections at 74.9 °C and 72.0 °C, respectively. The SMC1-SG's viscosity reduction pattern was maintained even at high temperatures (65 °C). Gelation by metal cations was observed in Fe3+ and Cr3+ solutions for both SG and SMC1-SG. Antibacterial activities of SG and SMC1-SG against Escherichia coli and Staphylococcus aureus were also observed. Therefore, like SG, SMC1-SG may be a potential biomaterial for pharmaceutical, cosmetic, and food industries.

Structure and physicochemical properties of amphiphilic agar modified with octenyl succinic anhydride

A novel amphiphilic agar with high transparency and freeze-thaw stability was prepared using octenyl succinic anhydride (OSA). Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy confirmed that the hydrophobic OS groups were successfully introduced in OSA-modified agar (OSAR) backbone. The OSAR showed higher emulsion stability and oil loading capacity than the native agar (NA). Compared with gel transparency (47.1 %), syneresis (42.1 %) of NA, OSAR exhibited high gel transparency (80 %) and low syneresis (3.3 %) when the degree of substitution (DS) was 0.06 and 0.12, respectively. Meanwhile, the OSAR showed a decreased interface tension and average molecular weight after modification. Thermogravimetric analysis indicated the thermal stability of OSAR was decreased, while texture profile analysis showed the springiness of the OSAR gel was enhanced. Dynamic rheology measurements revealed the OSAR with low gel strength displayed more liquid-like properties. Moreover, the OSAR exhibited lower turbidity and melting temperatures than the NA.