The development of plant protein-based delivery systems is often limited by poor stability and low retention efficiency under gastrointestinal conditions. This study investigated how pH (4 and 7) during external gelation influences the physicochemical properties, entrapment efficiency (EE), and in vitro gastrointestinal behaviour of alginate beads loaded with hemp protein concentrate (HPC), pea protein concentrate (PPC), or soy protein isolate (SPI). Zeta potential and Fourier transform infrared (FTIR) analyses suggested that at pH 4, the charge profiles of plant proteins favoured electrostatic association with anionic alginate, which was associated with higher EE values, with HPC achieving the maximum of 89.5% at pH 4. Conversely, at pH 7, electrostatic repulsion between biopolymers was associated with reduced EE. During in vitro digestion, beads formulated at pH 4 exhibited greater protein release than those prepared at pH 7, consistent with the expansion of the polymeric network under intestinal conditions. Size exclusion chromatography showed that released proteins underwent extensive proteolysis, generating low-molecular-weight fractions smaller than 300 Da. These results indicate that gelation pH is a relevant processing parameter for modulating protein retention and the extent of protein release of simulated digestion in alginate-based systems, with potential applications in protein-enriched food formulations.
Sea cucumber mouthpart peptides (SCPs) are marine bioactive peptides with considerable application potential. However, their oral delivery remains challenging because of their poor stability and low intestinal bioavailability. To develop a delivery system for SCPs with gastric protection and pH-responsive intestinal sustained-release properties, double-layer gel beads (SCP-BMs) were fabricated through ionic gelation, with SCPs as the core material and sodium alginate (SA) and chitosan (CS) as the wall materials. The preparation conditions of the gel beads were optimized using single-factor experiments and response surface methodology (RSM). The optimized gel beads were then characterized for their morphology, thermal stability, in vitro gastrointestinal release behavior, and antioxidant activity. The results showed that the optimal preparation conditions were 1.67% (w/v) sodium alginate, 0.96% (w/v) chitosan, and 2.16% (w/v) CaCl2. Under the optimized conditions, the encapsulation efficiency (EE) reached 94.33%, significantly higher than that of the single-layer gel beads (SCP-SMs, 58.61%). Structural characterization showed that SCP-BMs exhibited a more compact structure than SCP-SMs, along with improved thermal stability. In vitro release and antioxidant assays demonstrated that SCP-BMs exhibited better gastric protection, pH-responsive intestinal release, and higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity compared with SCP-SMs. This study demonstrated that the SA/CS double-layer wall material system effectively improved the encapsulation efficiency, structural stability, and intestinal release behavior of SCP gel beads. These findings provide a feasible strategy for the development of SCP delivery systems and offer a theoretical basis for the high-value utilization of sea cucumber byproducts.
Yi-Ge Wu, Li-Jun Hu, Yue Li et al.· Marine Drugs· 0 citations
Citral is often used as a flavoring agent in food, beverages, and cosmetics. It deteriorates during storage due to its susceptibility to oxygen and acidic pH. In this work, we examined the influence of protein type, pH, and ratio on citral nanoencapsulation. To achieve this objective two protein types, whey protein concentrate (WPC) and skim milk (S), were used to nanoencapsulate citral via complex coacervation. Response surface methodology (RSM) using a Box-Behnken design optimized pH, protein type, and ratio. The maximum desirability was observed in 4% WPC and 1% carrageenan at pH 3. Different pH values (3, 6, and 9) were used for post-optimization characterization of the freeze-dried optimized formulation. The encapsulation efficiencies ranged from 64% to 35%, depending on pH. SEM results of citral-loaded nanocomplexes confirmed that the nanocapsules were spherical without holes under acidic conditions. These findings suggest that WPC-carrageenan complex coacervation is a promising approach for citral nanoencapsulation and may improve its applicability in food systems.
This study investigates how electrostatic interactions between whey protein isolate (WPI) and polysaccharides (konjac glucomannan, guar gum, pectin, sodium alginate, chitosan) affect the stability and encapsulation of high-internal-phase emulsions (HIPEs, oil fraction >74%), revealing charge-driven structural and network stabilization mechanisms. The findings demonstrate that anionic WPI (pH 7.0) alone was more effective than cationic WPI (pH 4.0) in stabilizing oil-in-water HIPEs. Neutral polysaccharides enhanced emulsifying performance through viscosity-induced stabilization. While electrostatic repulsion increased ζ-potential of the complexes, thereby synergistically strengthening hydrophobic interaction-driven emulsifying activity. In contrast, excessive attraction (pectin, ζ-potential -17.0 mV) destabilized structural network through bridging or depletion flocculation, whereas moderate attraction (sodium alginate, ζ-potential -11.5 mV), facilitated the formation of stable emulsion systems. Notably, sodium alginate-WPI systems demonstrated robust stability (for 4 months) across all electrostatic conditions and offered excellent biocompatibility (<5%) and probiotic protection (>9.05 log CFU/mL). Collectively, these findings elucidate the mechanism of electrostatic tuning in stabilization of HIPEs, providing a promising approach for probiotics delivery.
The use of biodegradable hydrogels for the removal or controlled release of agrochemicals is a promising approach that has been widely investigated. This study aims to investigate the effect of chitosan (CH) and zeolite on polymerization solution viscosity, thermal properties, and sorption and desorption properties of the herbicides paraquat (PQ) and difenzoquat methylsulfate (DFZ), in different pH and ionic strength, using poly(methacrylic acid)-co-polyacrylamide (PMAA-co-PAAm) as polymeric matrices. The results indicated that the presence of polysaccharide CH and zeolite increased the thermal stability and viscosity of the polymerization solution. From kinetic studies, it was possible to observe that zeolite-based nanocomposites had slower adsorption of DFZ (k2 = 0.026 g/mg.h) when compared to PQ (k2 = 0.054 g/mg.h) pesticides. However, slower adsorption led to a more controlled release, whereas a broader pH range improved herbicide retention in these nanocomposites. Another important factor was the influence of Ca2+ and Al3+ ions on the release behavior, releasing almost all the herbicide contained in the hydrogels, except for the nanocomposites, which released 87.3% of the sorbed PQ. These results indicate that the performance of these materials is influenced by both the application environment and the molecular structure of the compound. In this way, these nanocomposites demonstrate high efficiency in removing unwanted chemicals from water, aligning their application primarily with environmental remediation and wastewater treatment systems to mitigate pesticide pollution.
Fabrício C. Tanaka, U. G. Yonezawa, M. D. de Moura et al.· Bioscience Nanotechnology· 0 citations
Postharvest spoilage of fresh fruits demands efficient bio-based packaging films. Here, chitosan/gelatin (CG) films were incorporated with β-cyclodextrin-encapsulated clove essential oil microcapsules (β-CD@CEO MCs) at varying loadings. The results suggested that CEO encapsulation occurred within β-CD cavities and hydrogen-bond binding of MCs to the CG matrix. At 0.4% MCs, the composite film showed 60.11% higher tensile strength, excellent UV shielding, lower water vapor transmission rate, and strong antioxidant activity (DPPH 89.6%, ABTS 97.1), along with 58.21% biodegradation after 16 days of soil burial. In vitro release studies revealed a pH-responsive sustained release profile of CEO from the composite films, with faster release under acidic conditions (98.5% at pH 3.5 after 72 h) compared to neutral conditions (87.2% at pH 7.0), indicating the potential for targeted release on the weakly acidic grape surface. The film also exhibited significant antimicrobial effects against Botrytis cinerea, Penicillium gladioli, Staphylococcus aureus, and Escherichia coli. In table grape preservation, CG/MCs-0.4 film effectively delayed decay, reduced weight loss by 38.79%, maintained firmness and color, and preserved higher levels of soluble solids, titratable acidity, reducing sugars, and vitamin C compared to polyethylene packaging and untreated controls.