Search Results (28)

Background/Objectives: Natural calcium carbonate materials such as Rügen chalk have a long history of use in balneology and rehabilitation, particularly for musculoskeletal disorders, yet their application remains largely confined to traditional, labour-intensive forms such as powders, suspensions, and packs, which limit usability and broader clinical translation. This study aimed to develop an alginate-based solid foam incorporating Rügen chalk and to evaluate how key formulation components influence its structural, mechanical, and thermal properties relevant for therapeutic use. Methods: Alginate–chalk foams were prepared by mechanical mixing of a sodium alginate–Rügen chalk paste with an amino acid-based surfactant, while in situ CO₂ generation from D–glucono–δ–lactone (GDL) induced calcium-mediated alginate gelation and foam stabilization. A central composite design with response surface methodology was used to assess the effects of alginate, chalk, and Perlastan^®–GDL content on foam pH, overrun, firmness, springiness, pore volume, sphericity, pore density, specific internal surface area, and heat-loss time. Foam microstructure was characterized by optical microscopy and microcomputed tomography (µCT), and the thermal conductivity and cooling behaviour of the selected formulation were compared with therapeutic peat. Results: Stable, elastic solid foams with a three-dimensional porous architecture were obtained across the investigated composition range. Foam overrun (30.8–57.1%) was primarily governed by sodium alginate and Rügen chalk concentrations, while firmness (7.4–15.2 N) increased predominantly with alginate content, and springiness remained high (70–78%), indicating good elastic recovery. Response surface modelling and ANOVA confirmed sodium alginate as the dominant factor influencing both mechanical and structural properties, with statistically significant effects on overrun, firmness, springiness, heat loss, porosity, and specific internal surface. µCT analysis revealed that all foam formulations were predominantly composed of fine, closed-cell pores, with over 96% of pores having volumes below 0.5 mm³ and a consistent median pore volume of 0.02 mm³. Structural differences between formulations were governed primarily by pore number and spatial distribution rather than pore size. Strong correlations were identified between µCT-derived parameters, particularly between specific internal surface, porosity, and pore density, confirming that internal architecture is controlled by pore population rather than individual pore dimensions. Thermal analysis demonstrated that the optimized formulation exhibited thermal conductivity comparable to therapeutic peat and maintained clinically relevant temperatures (35–45 °C) for more than one hour. Based on predefined performance criteria (overrun ≥ 50%, firmness ≤ 10 N, heat loss ≥ 120 s), formulation 7 was identified as optimal, combining favourable mechanical properties, structural uniformity and thermal retention. Conclusions: Alginate-based solid foams incorporating Rügen chalk constitute a feasible and tunable platform that combines efficient mineral loading, elastic porosity, and effective heat retention, offering a practical and modern alternative to conventional mineral-based therapeutic applications in balneology and rehabilitation. Full article

Electrostatic protein–polysaccharide hydrogels are attractive materials formed without thermal denaturation or chemical crosslinkers and at low biopolymer contents. Their broader application in foods, however, has been limited by slow gelation, with network development often requiring many hours (~18 h). In this study, millimeter-scale hydrogel beads were fabricated from amaranth proteins and xanthan gum by extrusion into glucono-δ-lactone (GDL) solutions (1–5 mg/mL) using hardening times of 10 or 30 min. Beads were successfully formed under all conditions (3.07–3.95 mm diameter), and their physicochemical properties, intermolecular interactions, microstructure, and gel strength were evaluated. Electrostatic attraction remained the dominant force driving gelation. Furthermore, 10 min hardening favored interpolymeric electrostatic interactions, whereas longer exposure reduced them and promoted hydrogen bonding and hydrophobic interactions. These molecular rearrangements were accompanied by a decreased size, lower water retention capacity (WRC), and higher mechanical strength. The mildest treatment (1 mg/mL GDL, 10 min) was post-loaded with a coffee pulp phenolic extract and showed reduced gel strength and electrostatic interactions, suggesting competition for binding sites within the macromolecular network. The extrusion of amaranth protein–xanthan gum mixtures into a GDL bath markedly shortens electrostatic gelation time, supporting this approach as a potential alternative to ionic gelation for the production of millimeter-scale hydrogel beads for food applications. Full article

In this study, we investigated the effect of ultrasound-assisted Maillard glycosylation reaction time on the structural, physicochemical, and acid-induced gel properties of Zophobas morio protein–maltodextrin (ZMP–MD) conjugates. Ultrasound treatment up to 45 min (100 kHz, 450 W, 70 °C) significantly accelerated the conjugation efficiency (15.81%) compared to that of wet heating at 70 °C for 6 h (13.62%) (p < 0.05). Fourier transform infrared spectroscopy (FT-IR) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses confirmed that both Maillard glycosylation methods formed ZMP–MD conjugates. In addition, the results for secondary structure, surface hydrophobicity, and zeta potential revealed that the ultrasound treatment promoted greater protein structural unfolding, decreasing α-helix while increasing β-sheet and random coil content compared to wet heating. These changes in structural and physicochemical properties of ZMP–MD conjugates impacted the glucono-δ-lactone (GDL)-based acid-induced gel properties. Even though Maillard glycosylation with MD weakened gel properties compared to native ZMP, the gel obtained after 45 min of ultrasound treatment exhibited a higher storage modulus, gel strength, and water-holding capacity than the wet-heated ZMP–MD gel. In conclusion, these findings suggest that properly controlled ultrasound-assisted Maillard glycosylation can modify protein structure, potentially improving its gel properties. Full article

Acid-induced coagulation of milk plays an important role in the production of dairy products with high quality. The gel texture is significantly affected by processing conditions such as heat treatment and mineral composition. This study examines the effect of moderate heat treatment applied at 65 °C for 5 min and ionic calcium supplementation (10 mM CaCl₂) on coagulation at 30 °C for 180 min of cow’s milk induced by glucono-δ-lactone (GDL). A slow and gradual protonation was induced, reaching pH values of 4.3–4.5. Rheological analysis revealed an increase in G′ from 59.28 Pa for raw milk gel to 224.1 Pa after the addition of CaCl₂. An inverse trend was observed for gel produced with heated milk after the addition of CaCl₂. However, the gel produced from calcium-fortified heated milk showed G′ values of 136.7 Pa. Turbiscan analysis showed the highest TSI for gels made from heated milk. Scanning electron microscopy analysis indicates that raw milk gels supplemented with CaCl₂ exhibit dense and homogeneous networks, while heat-treated GDL gels show more porous networks. Mid-infrared (3000–2800 cm⁻¹, 1700–1500 cm⁻¹, and 1500–900 cm⁻¹) and fluorescence spectra revealed changes in protein–protein, protein–water, and protein–protein–lipid interactions throughout coagulation. Full article

In this paper, the effect of sodium carboxymethyl cellulose (CMC-Na) on the structure and gel properties of ovalbumin (OVA) gels induced by glucono-δ-lactone (GDL) and heat treatment was investigated. The results suggested that the interaction between CMC-Na and OVA was mainly through hydrogen bonding. The water-holding capacity of CMC-Na/OVA composite gels gradually increased as CMC-Na concentration increased, while the viscoelasticity was first enhanced and then weakened. The hardness and elasticity of the composite gels were higher than those of the pure OVA gels when the CMC-Na concentration was lower than 0.4%. However, the hardness and springiness of the composite gels decreased significantly after further increasing the CMC-Na addition. The change in texture properties induced by CMC-Na under glucono-δ-lactone (GDL) and heat treatment provided theoretical support for developing soft gel products with abundant protein for special groups, such as the elderly, teenagers, and pregnant women. Full article

This study aimed to investigate the effects of high-pressure homogenization (HPH) (0, 25, 50, 100, and 150 MPa) pretreatment on the structural, rheological, and gelling properties of alkaline-extracted hazelnut protein isolate gels induced by glucono-δ-lactone (GDL). Homogenization pretreatment shortened the time required to obtain the maximum G′ value (12.65 Pa) from 32 to 28 min in the control sample. The particle size of protein isolates decreased with increasing pressure, resulting in lower particle size aggregates after gelation and in a denser gel structure with increasing gel hardness (from 1.52 g to 2.06 g) and WHC (from 31.95% to 48.36%). FT-IR spectroscopy revealed that HPH pretreatment and gelling time changed the secondary structure of the protein, promoting the formation of hazelnut protein gels. Hazelnut gel pretreated at 150 MPa exhibited the highest apparent viscosity and G′ value, indicating a more elastic and stronger gel network structure. The gel intermolecular force results showed that the contribution of hydrophobic interactions to gel formation was significant, and the chemical bond content of the gels increased with the increase in pressure up to 100 MPa. The physical stability of the gels was also improved by HPH pretreatment. Although the best WHC and physical stability were observed in the 100 MPa-pretreated gel sample, the hazelnut protein isolate pretreated at 150 MPa exhibited the best gel performance. Overall, HPH pretreatment has the potential to enhance hazelnut protein gel properties for industrial food applications. Full article

A polydopamine polyelectrolyte hydrogel was developed by ionic crosslinking dextran sulfate with a copolymer of polyethyleneimine and polydopamine. Gelation was promoted by the slow hydrolysis of glucono-δ-lactone. Within this hydrogel, silver nanoparticles were generated in situ, ranging from 25 nm to 200 nm in size. The antibacterial activity of the hydrogel was proportional to the quantity of silver nanoparticles produced, increasing as the nanoparticle count rose. The hydrogels demonstrated broad-spectrum antibacterial efficacy at concentrations up to 10⁸ cells/mL for P. aeruginosa, K. pneumoniae, E. coli and S. aureus, the four most prevalent bacterial pathogens in chronic septic wounds. In ex vivo studies on human skin, biocompatibility was enhanced by the presence of polydopamine. Dextran sulfate is a known irritant, but formulations with polydopamine showed improved cell viability and reduced levels of the inflammatory biomarkers IL-8 and IL-1α. Silver nanoparticles can inhibit cell migration, but an ex vivo human skin study showed significant re-epithelialization in wounds treated with hydrogels containing silver nanoparticles. Full article

Soluble starch (SS) could significantly accelerate the process of bovine serum albumin (BSA) cold-set gelation by glucono-δ-lactone (GDL) and microbial transglutaminase (MTGase) coupling inducers, and enhance the mechanical properties. Hardness, WHC, loss modulus (G″) and storage modulus (G′) of the gel increased significantly, along with the addition of SS, and gelation time was also shortened from 41 min (SS free) to 9 min (containing 4.0% SS); the microstructure also became more and more dense. The results from FTIR, fluorescence quenching and circular dichroism (CD) suggested that SS could bind to BSA to form their composites, and the hydrogen bond was probably the dominant force. Moreover, the ability of SS to bind the original free water in BSA gel was relatively strong, thereby indirectly increasing the concentration of BSA and improving the texture properties of the gel. The acceleration of gelling could also be attributed to the fact that SS reduced the negative charge of BSA aggregates and further promoted the rapid formation of the gel. The embedding efficiency (EE) of quercetin in BSA-SS cold-set gel increased from 68.3% (SS free) to 87.45% (containing 4.0% SS), and a controlled-released effect was detected by simulated gastrointestinal digestion tests. The work could put forward new insights into protein gelation accelerated by polysaccharide, and provide a candidate for the structural design of new products in the food and pharmaceutical fields. Full article

To enhance the mechanical strength and cell adhesion of alginate hydrogel, making it satisfy the requirements of an ideal tissue engineering scaffold, the grafting of Arg-Gly-Asp (RGD) polypeptide sequence onto the alginate molecular chain was conducted by oxidation of sodium periodate and subsequent reduction amination of 2-methylpyridine borane complex (2-PBC) to synthesize alginate dialdehyde grafted RGD derivatives (ADA-RGD) with good cellular affinity. The interpenetrating network (IPN) composite hydrogels of alginate/polyvinyl alcohol/cellulose nanocrystals (ALG/PVA/CNCs) were fabricated through a physical mixture of ion cross-linking of sodium alginate (SA) with hydroxyapatite/D-glucono-δ-lactone (HAP/GDL), and physical cross-linking of polyvinyl alcohol (PVA) by a freezing/thawing method, using cellulose nanocrystals (CNCs) as the reinforcement agent. The effects of the addition of CNCs and different contents of PVA on the morphology, thermal stability, mechanical properties, swelling, biodegradability, and cell compatibility of the IPN composite hydrogels were investigated, and the effect of RGD grafting on the biological properties of the IPN composite hydrogels was also studied. The resultant IPN ALG/PVA/CNCs composite hydrogels exhibited good pore structure and regular 3D morphology, whose pore size and porosity could be regulated by adjusting PVA content and the addition of CNCs. By increasing the PVA content, the number of physical cross-linking points in PVA increased, resulting in greater stress support for the IPN composite hydrogels of ALG/PVA/CNCs and consequently improving their mechanical characteristics. The creation of the IPN ALG/PVA/CNCs composite hydrogels’ physical cross-linking network through intramolecular or intermolecular hydrogen bonding led to improved thermal resistance and reduced swelling and biodegradation rate. Conversely, the ADA-RGD/PVA/CNCs IPN composite hydrogels exhibited a quicker degradation rate, attributed to the elimination of ADA-RGD by alkali. The results of the in vitro cytocompatibility showed that ALG/0.5PVA/0.3%CNCs and ADA-RGD/PVA/0.3%CNCs composite hydrogels showed better proliferative activity in comparison with other composite hydrogels, while ALG/PVA/0.3%CNCs and ADA-RGD/PVA/0.3%CNCs composite hydrogels displayed obvious proliferation effects, indicating that PVA, CNCs, and ADA-RGD with good biocompatibility were conducive to cell proliferation and differentiation for the IPN composite hydrogels. Full article

Herein, improving the antibacterial activity of a hydrogel system of sodium alginate (SA) and basic chitosan (CS) using sodium hydrogen carbonate by adding AgNPs was investigated. SA-coated AgNPs produced by ascorbic acid or microwave heating were evaluated for their antimicrobial activity. Unlike ascorbic acid, the microwave-assisted method produced uniform and stable SA-AgNPs with an optimal reaction time of 8 min. Transmission electron microscopy (TEM) confirmed the formation of SA-AgNPs with an average particle size of 9 ± 2 nm. Moreover, UV-vis spectroscopy confirmed the optimal conditions for SA-AgNP synthesis (0.5% SA, 50 mM AgNO₃, and pH 9 at 80 °C). Fourier transform infrared (FTIR) spectroscopy confirmed that the –COO⁻ group of SA electrostatically interacted with either the Ag⁺ or –NH₃⁺ of CS. Adding glucono-δ-lactone (GDL) to the mixture of SA-AgNPs/CS resulted in a low pH (below the pKa of CS). An SA-AgNPs/CS gel was formed successfully and retained its shape. This hydrogel exhibited 25 ± 2 mm and 21 ± 1 mm inhibition zones against E. coli and B. subtilis and showed low cytotoxicity. Additionally, the SA-AgNP/CS gel showed higher mechanical strength than SA/CS gels, possibly due to the higher crosslink density. In this work, a novel antibacterial hydrogel system was synthesized via 8 min of microwave heating. Full article

Convenient cuts of poultry products are of significant interest, but they are perishable products with a short shelf life. Modified atmosphere packaging (MAP) or the application of active packaging based on edible and biodegradable coatings could extend the shelf life of perishable foods. The aim of the present work was the kinetic modelling of the effect of MAP and active coatings with antimicrobial agents on the microbial growth and shelf life of chicken cuts. Broiler chicken thighs processed with pectin-based (2% w/w aqueous solution) edible coatings enriched with 1% extract of citrus bioflavonoids (flavomix) or 0.5% glucono-δ-lactone were stored under aerobic conditions at 0, 5 and 10 °C. Untreated thighs were also stored aerobically or in MAP (42.7% O₂, 18.5% CO₂). Quality evaluation was based on the growth of spoilage bacteria (TVC, Pseudomonas spp., Brochothrix thermosphacta), pH, colour, and sensory scoring. The tested quality indices were kinetically modelled and the Arrhenius model was used for the definition of the temperature dependence of the quality loss rates. Pseudomonas spp. dominated spoilage at all packaging and temperature conditions. Microbial growth correlated well with sensory degradation (E_a = 80–100 kJ/mol). Glucono-δ-lactone-enriched edible coatings resulted in 2 days of shelf life extension for chicken thighs at 5 °C. MAP and active, edible coatings with citrus extract showed a similar effect on the quality deterioration rate, and thus the shelf life of chicken cuts. Based on microbial growth, the shelf life was 6–7, 11, and 13 days at 5 °C for the control, EC-glu, MAP, and EC-flav samples, respectively (limit of acceptability = 10⁷ cfu/g for TVC). The results of the study show the potential for using MAP or edible, active coatings to extend the shelf life and improve the commercial value of broiler chicken cuts. Full article

We provide a method for quantifying the kinetics of gelation in milk acidified with glucono-$\delta$-lactone (GDL) using image analysis techniques, particle image velocimetry (PIV), differential variance analysis (DVA) and differential dynamic microscopy (DDM). The gelation of the milk acidified with GDL occurs through the aggregation and subsequent coagulation of the casein micelles as the pH approaches the isoelectric point of the caseins. The gelation of the acidified milk with GDL is an important step in the production of fermented dairy products. PIV qualitatively monitors the average mobility of fat globules during gelation. The gel point estimated by PIV is in good agreement with that obtained by rheological measurement. DVA and DDM methods reveal the relaxation behavior of fat globules during gelation. These two methods make it possible to calculate microscopic viscosity. We also extracted the mean square displacement (MSD) of the fat globules, without following their movement, using the DDM method. The MSD of fat globules shifts to sub-diffusive behavior as gelation progresses. The fat globules used as probes show the change in matrix viscoelasticity caused by the gelling of the casein micelles. Image analysis and rheology can be used complementarily to study the mesoscale dynamics of the milk gel. Full article

Alginate hydrogel commonly suffers from defects, such as weak mechanical properties, the shortage of long-term stability in physiological medium and the lack of mammalian cell adhesivity due to its strong hydrophilicity in biomedical application. For this reason, the homogeneous alginate hydrogels (Alg Gel) were successfully prepared by the D-glucono-δ-lactone/hydroxyapatite (HAP/GDL) cross-linking system, and then, the physical blending and alternating electrostatic assembly technology were proposed to fabricate alginate composite hydrogels (Alg-GT, Alg-CS-GT and ALG/GT-CS). The feasibility of the design methods was verified through the comparative analysis of their physicochemical properties and biological activity. In particular, the effects of physical blending and alternating electrostatic assembly technology on the pore structure, mechanical properties, swelling, degradation, cell adhesion and proliferation of composite hydrogels were also investigated. Experimental results showed that the formation of polyelectrolyte complexes by electrostatic assembly between biological macromolecules and the covalent cross-linking of EDC/NHS to GT improved the vulnerability of ion cross-linking, enhanced the mechanical properties and swelling stability of the composite hydrogels, and regulated their pore structure and in vitro biodegradability properties. Furthermore, MC3T3-E1 cells could exhibit good cell adhesion, cell viability and cell proliferation on the alginate composite hydrogels. Among them, Alg-CS-GT showed the best cell proliferation ability and differentiation effect due to its good cell adhesion. In view of the excellent physicochemical properties and biological activity of Alg-CS-GT, it exhibited great potential in biomedical application for tissue engineering. Full article

Due to growing interest in health and sustainability, the demand for replacing animal-based ingredients with more sustainable alternatives has increased. Many studies have been conducted on plant-based meat, but only a few have investigated the effect of adding a suitable binder to plant-based meat to enhance meat texture. Thus, this study investigated the effects of the addition of transglutaminase (TG) and glucono-δ-lactone (GdL) on the physicochemical, textural, and sensory characteristics of plant-based ground meat products. The addition of a high quantity of GdL(G10T0) had an effect on the decrease in lightness (L* 58.98) and the increase in redness (a* 3.62). TG and GdL also decreased in terms of cooking loss (CL) and water holding capacity (WHC) of PBMPs. G5T5 showed the lowest CL (3.8%), while G3T7 showed the lowest WHC (86.02%). The mechanical properties also confirmed that G3T7-added patties have significantly high hardness (25.49 N), springiness (3.7 mm), gumminess (15.99 N), and chewiness (57.76 mJ). The improved textural properties can compensate for the chewability of PBMPs. Although the overall preference for improved hardness was not high compared to the control in the sensory test, these results provide a new direction for improving the textural properties of plant-based meat by using binders and forming fibrous structures. Full article

In this study, the protein bioaccessibility of soymilk gels produced by the addition of glu-cono-δ-lactone (GDL) and fermentation with lactic acid bacteria (LAB) was examined using an in vitro gastrointestinal simulated digestion model. The in vitro protein digestibility, soluble protein content, free amino acids contents, degree of hydrolysis, electrophoretic patterns, and peptide content were measured. The results suggested that acid-induced soymilk gel generated by GDL (SG) showed considerably reduced in vitro protein digestibility of 75.33 ± 1.00% compared to the soymilk gel induced by LAB (SL) of 80.57 ± 1.53% (p < 0.05). During the gastric digestion stage, dramatically higher (p < 0.05) soluble protein contents were observed in the SG (4.79–5.05 mg/mL) than that of SL (4.31–4.35 mg/mL). However, during the later intestinal digestion phase, the results were the opposite. At the end of the gastrointestinal digestion phase, the content of small peptides was not significantly different (p > 0.05) between the SL (2.15 ± 0.03 mg/mL) and SG (2.17 ± 0.01 mg/mL), but SL showed higher content of free amino acids (20.637 g/L) than that of SG (19.851 g/L). In general, soymilk gel induced by LAB had a higher protein bioaccessibility than the soymilk gel coagulated by GDL. Full article