Novel food-grade water-in-water Pickering emulsions for encapsulation and delivery of hydrophilic bioactives.

Kinetic and Oxidative Stability of Oil-in-Water Pickering Emulsions Stabilized by Lysozyme-Ferulic Acid Conjugates

The demand for ingredients with natural appeal has driven the development of multifunctional natural emulsifiers. This study aimed to synthesize covalent conjugates of lysozyme (LYS) and ferulic acid (FA) via a free radical reaction and investigate their application in stabilizing soybean oil Pickering emulsions. Conjugate formation was confirmed by SDS-PAGE and FTIR and UV-Vis spectroscopy, indicating alterations in the protein’s tertiary structure. The LYS-FA conjugate exhibited techno-functional properties superior to native lysozyme, including higher emulsifying capacity and antioxidant activity, with inhibition values above 74% for both DPPH and ABTS. Furthermore, in vitro digestion studies demonstrated that conjugation protected FA from degradation in the gastric phase. Oil-in-water Pickering emulsions were prepared with different conjugate concentrations from 2 to 4% w/w in the aqueous phase. The formulation with 4% LYS-FA resulted in an excellent kinetic stability, showing no creaming for 8 days. Rheology revealed pseudoplastic behavior with a predominantly elastic character, where G’ was higher than G’’, suggesting the formation of a robust network at the interface. In addition to physical stability, the Pickering emulsions significantly retarded the primary and secondary lipid oxidation of the encapsulated soybean oil compared to the control, attributed to the interfacial barrier and antioxidant action formed by the conjugate. These results suggest that LYS-FA conjugates are promising candidates as emulsifiers with good techno-functional properties and antioxidant capacity for applications in the food industry.

Soy Protein Isolate-Chitosan Maillard Graft-Stabilized Curcumin-Loaded Emulsions for Encapsulation and Sustained Release

Hydrophobic bioactive compounds are difficult to deliver because of poor water solubility, limited stability, and uncontrolled release. In this study, chitosan-soy protein isolate (CS-SPI) conjugates were prepared by dry-heat Maillard reaction and used as natural polymeric emulsifiers for curcumin-loaded emulsions. The highest grafting degree of 15.3% was obtained at 70 °C, 74.50% relative humidity, 96 h, and a CS:SPI mass ratio of 1:3. Compared with chitosan and CS-SPI non-covalent complex-stabilized emulsions, the CS-SPI conjugate-stabilized emulsion showed the smallest droplets (7.23 μιη) and a more uniform distribution. It maintained high encapsulation efficiency after 6 days of storage (94.28%) and suppressed burst release during simulated gastric digestion, extending curcumin release to about 72 h. These results suggest that CS-SPI conjugates improve emulsion stability and sustained-release performance.

Chitosan–cinnamaldehyde–whey protein concentrate stabilized W1/O/W2 double emulsion for co-encapsulation of tea polyphenols and β-carotene

Gelatin/chitosan/MIL-101(Fe) hybrid-stabilized Pickering emulsion with dual pH/redox responsiveness for sustained pendimethalin release and improved foliar adhesion.

Sustainable and stimuli-responsive delivery systems provide a promising strategy to improve agrochemical utilization efficiency while mitigating the environmental risks of conventional pesticide formulations. Herein, we report a volatile organic solvent-free Pickering emulsion stabilized by gelatin, chitosan, and MIL-101(Fe) nanoparticles, which achieves dual pH- and redox-responsive co-delivery of the herbicide pendimethalin and antibacterial thyme essential oil. The pH-triggered swelling of the biopolymer matrix and the redox-induced degradation of the MIL-101(Fe) framework jointly contribute to on-demand release of active ingredients. Meanwhile, the composite stabilizer system significantly enhances foliar deposition, as reflected by a 30.8% decrease in contact angle and an 88.9% increase in liquid holding capacity compared with a commercial emulsifiable concentrate (EC). The Pickering emulsion shows herbicidal activity equivalent to that of the commercial formulation, together with favorable antibacterial performance and no obvious phytotoxicity to maize. Collectively, this work constructs a sustainable, multifunctional, and stimuli-responsive agrochemical delivery platform with enhanced deposition efficiency and biosafety, providing a universal strategy for the design of next-generation green pesticide formulations.

Photothermal controlled-release packaging films based on chitosan-gelatin incorporated with pickering emulsions for tea tree oil delivery and their application in freshness preservation of berries.

Natural antimicrobial agents are both environmentally friendly and safe, and exhibit excellent biocompatibility. However, their instability and rapid release characteristics limit their application in food preservation packaging. In this study, a photothermal-responsive packaging film was developed by incorporating a Pickering emulsion of soy protein isolate-tannic acid-Fe3+(STF) nanoparticles stabilizing tea tree oil (TTO) into a chitosan (CS)/gelatin (Gel) matrix. The STF nanoparticles, synthesized via coordination-driven self-assembly, stabilized the Pickering emulsion and achieved an encapsulation efficiency of 84% for TTO. Under near-infrared (NIR) irradiation, STF nanoparticles transform light energy into thermal energy. On the one hand, the localized increase in temperature provides the film with a certain sterilizing effect. On the other hand, the film allows for the rapid, controlled release of tea tree oil as needed. Through the synergistic effect of localized thermal therapy and controlled release of essential oils, the film exhibits over 98% antibacterial activity against E. coli and S. aureus. Furthermore, the resultant film has outstanding mechanical strength, barrier properties, and antioxidant effects. Preservation experiments were ultimately carried out using strawberries and grapes as representative berries, and the results showed that the film can extend the shelf life by 3-8 days depending on the fruit type. These results demonstrate the application potential of this photothermal controlled-release film in the field of berry preservation.

Pickering emulsions for intelligent curcumin delivery: Synergistic stabilization by starch nanocrystals and soy β-conglycinin or glycinin.

Starch nanocrystals (SNCs) derived from rice starch were complexed with soybean β-conglycinin (7S) or glycinin (11S) to develop food-grade Pickering emulsifiers for curcumin delivery. The effects of the SNC-to-protein mass ratio on particle structure, interfacial properties, emulsion stability, and gastrointestinal digestion were systematically evaluated. At an SNC-to-protein mass ratio of 1:1, the SNCs-7S and SNCs-11S complexes exhibited the smallest particle sizes of 110 ± 4 and 234 ± 6 nm, respectively. Their three-phase contact angles approached 90°, indicating favorable interfacial wettability. SNCs induced concentration-dependent fluorescence quenching of 7S and 11S, with maximum quenching efficiencies of 61.02 ± 1.41% and 37.51 ± 1.09%, respectively. Raman spectroscopy and molecular docking analyses indicated that complex formation involved rearrangements of the protein secondary structure and hydrogen bonding. All calculated binding energies were below -6.0 kcal/mol, with the lowest value of -6.5 kcal/mol observed for SNCs-11S. Pickering emulsions containing 60% soybean oil exhibited shear-thinning and predominantly elastic behavior (G' > G″). The 1:1 composite systems formed the strongest network structures and exhibited no evident creaming, flocculation, or oiling-off after storage at 4 °C for 30 days. The SNCs-7S emulsion achieved a curcumin encapsulation efficiency (EE) and loading capacity of 90% and 7.5%, respectively, exceeding the corresponding values of 86% and 6.0% obtained for the SNCs-11S emulsion. After intestinal digestion, free fatty acid release from the SNCs-7S and SNCs-11S emulsions reached 46.31 ± 2.71% and 40.68 ± 0.71%, respectively. Overall, the 1:1 SNCs-7S system exhibited the most favorable interfacial assembly, storage stability, curcumin encapsulation, and lipid digestibility.