Yanling Lu

To evaluate the potential of defatted and dephenolized walnut meal as a modified functional food ingredient, this study examined how ball milling and processing time affect its structural, physicochemical, and functional properties. Walnut meal was ball-milled for 5, 10, 15, and 20 h. Ball milling increased the lightness and whiteness, reduced particle size, and broadened the particle size distribution into a characteristic three-peak pattern. Scanning electron microscopy revealed the progressive formation of flake-like surface structures. With increasing milling duration, free sulfhydryl groups, surface hydrophobicity, and solubility were increased, while dynamic surface tension decreased, leading to improved foaming capacity and foaming stability. SDS-PAGE confirmed that the primary structure remained unchanged, while Fourier transform infrared spectroscopy indicated a decrease in α-helix and β-sheet contents and an increase in random coil structures. X-ray diffraction revealed a reduction in the diffraction peak at 2θ = 8.963°, and differential scanning calorimetry showed irregular changes in the thermal stability with ball milling time. Overall, increasing ball milling time is beneficial for improving the functional properties of walnut meal, providing a preliminary theoretical reference for the potential application of walnut powder in foods with specific functional properties, such as aerated foods.

Objectives: To enhance the stability of proliposomes co-encapsulating Rosa roxburghii Tratt seed oil (RSO) and β-carotene (βC), sodium alginate (SA) and chitosan (CS) were utilized for bilayer surface modification. In this study, the proliposomes containing RSO and βC are referred to as Ps, while the modified formulations are denoted as sodium alginate–chitosan-modified proliposomes (SA-CS-Ps). Materials and methods: The physicochemical properties, structural characteristics, thermal stability, microstructure, rheological behavior, storage stability, and oxidation kinetics of SA-CS-Ps were investigated and compared with those of unmodified Ps and CS monolayer-modified Ps (CS-Ps). Results: The particle size and turbidity of Ps increased with the addition of modification layers, reaching 563.73 nm and 0.697, respectively, for SA-CS-Ps. CS and SA formed a protective bilayer through electrostatic interactions, which preserved the spherical structure of Ps while enhancing its apparent viscosity and stress. Thermal stability analysis indicated that the phase transition temperatures of CS-Ps and SA-CS-Ps were elevated by 10.57 and 15.76 °C, respectively, compared with that of unmodified Ps. During storage, the retention rates (RRs) of RSO and βC followed the order SA-CS-Ps>CS-Ps>Ps, whereas malondialdehyde and peroxide values exhibited the opposite trend. Elevated temperatures accelerated oxidation, thereby compromising the protective effect of the carriers. After 24 d at 4 °C, SA-CS-Ps demonstrated superior stability, with malondialdehyde of 0.016 μg/mg, peroxide value of 2.697 mmol/kg, and RRs of RSO of 97.15% and βC of 96.37%. The oxidation kinetics conformed to a first-order reaction model. Conclusions: Given its enhanced protection against degradation and stability, SA-CS-Ps represents a promising candidate for the delivery of sensitive bioactive compounds. This study provides a theoretical basis for the application of bilayer-modified proliposomes in functional food delivery systems requiring enhanced stability.

Soy protein isolate (SPI)–soy isoflavone (SI) complexes were prepared via a pH-driven method at varying SI concentrations (0–7.0 mg/mL) to study their interactions and to analyze the structural and functional characteristics of the complexes. The findings showed that the SPI-SI complexes’ particle size first reduced and then rose with higher SI concentration. Fourier transform infrared spectroscopy revealed a reduction in β-sheet content (35.72%), indicating a limited structural rearrangement toward increased conformational flexibility. Consistently, fluorescence spectroscopy revealed that the fluorescence intensity of SPI diminished with the addition of SI, suggesting hydrogen-bond-mediated interactions. At 3.0 mg/mL SI, the complexes exhibited optimal physicochemical properties, with the most negative zeta potential (−29.78 mV), a solubility increase from 41.90% to 64.70%, and an elevated denaturation temperature from 86.77 °C to 88.79 °C, as well as 1.25-fold higher emulsifying capacity, and 1.86-fold greater emulsion stability; collectively establishing 3.0 mg/mL SI as the concentration where functional advantages are maximized. Overall, these findings demonstrate that pH-induced, non-covalent SPI-SI complexation effectively modulates protein conformation and interfacial properties, providing a green and effective approach for enhancing plant protein functionality in food systems.

To investigate the effects of different treatment methods on soybean protein amyloid fibrils (SPAF), this study examined the effects of ultrasonication, cold plasma, heat, and NaCl treatment on the formation, structure, and functional properties of SPAF. SPAF structural analyses indicated that all treatments promoted SPAF assembly, with the order of effectiveness being: heat treatment > ultrasonication > cold plasma treatment > NaCl treatment. Regarding functional properties, the heat treatment group also demonstrated superior overall performance, including the highest solubility (88.15%), optimal emulsifying activity (79.63 m²/g) and foaming capacity (169.44%), and the highest thermal denaturation temperature (107.49 °C). Conversely, ultrasonication and cold plasma treatments, which generated shorter fibrils, offered moderate functional improvements. In contrast, NaCl treatment provided limited functional enhancement due to the formation of coarse aggregates. Consequently, heat treatment was identified as the most effective approach to promote SPAF formation and enhance functional properties. These findings provide a theoretical basis for the process optimization of SPAF in the food industry.

Walnut gluten (WGLU) is a plant-based protein rich in essential amino acids for the human body. Due to its poor water solubility and functional properties, its application in the food industry is limited. For the first time, this study looks into how different durations (0, 30, 60, 90, and 120 s) of atmospheric cold plasma (ACP) treatment affect the structure and functional properties of WGLU. ACP processing destroys the spatial structure of the WGLU and alters its functional properties. The comprehensive performance reached its best after 60 s of ACP treatment, the main manifestations included increased β-sheet content, reduced α-helix content, and unfolding of the tertiary structure, which ultimately improved the stability of emulsification and foam. Meanwhile, the solubility (86.35%), water retention rate (2.15 g/g), oil retention rate (5.31 g/g), emulsification rate (10.59 m²/g), and foaming rate (24.67%) of WGLU reached their maximum values. However, longer treatment times (90 and 120 s) induce WGLU aggregation, followed by decreased functional properties. In summary, the physicochemical and functional properties of WGLU can be significantly enhanced through ACP treatment, enhancing the bioavailability of gluten and providing an effective strategy for its application in food processing.

To enhance the functional properties of walnut protein isolate (WalPI), hydrophilic whey protein isolate (WPI) was selected to formulate WalPI-WPI nanoparticles (nano-WalPI-WPI) via a pH cycling technique. These nano-WalPI-WPI particles were subsequently employed to stabilize high internal phase Pickering emulsions (HIPEs). By adjusting the mass ratio of WalPI to WPI from 9:1 to 1:1, the resultant nano-WalPI-WPI exhibited sizes ranging from 70.98 to 124.57 nm, with a polydispersity index of less than 0.326. When the mass ratio of WalPI to WPI was 7:3, there were significant enhancements in various functional properties: the solubility, denaturation peak temperature, emulsifying activity index, and emulsifying stability index increased by 6.09 times, 0.54 °C, 318.94 m²/g, and 552.95 min, respectively, and the surface hydrophobicity decreased by 59.23%, compared with that of WalPI nanoparticles (nano-WalPI), with the best overall performance. The nano-WalPI-WPI were held together by hydrophobic interactions, hydrogen bonding, and electrostatic forces, which preserved the intact primary structure and improved resistance to structural changes during the neutralization process. The HIPEs stabilized by nano-WalPI-WPI exhibited an average droplet size of less than 30 μm, with droplets uniformly dispersed and maintaining an intact spherical structure, demonstrating superior storage stability. All HIPEs exhibited pseudoplastic behavior with good thixotropic properties. This study provides a theoretical foundation for enhancing the functional properties of hydrophobic proteins and introduces a novel approach for constructing emulsion systems stabilized by composite proteins as emulsifiers.