Recent advances in the plant protein-polyphenol interactions for the stabilization of emulsions

Proteins from plant sources including legumes, cereals and oilseeds are gaining attention due to their suitability for sustainable production, functionality, and positive consumer perception. On the other hand, polyphenols (PPs) are receiving considerable attention as natural ingredients in the human diet due to their potent antioxidant and anti-inflammatory properties. Recent studies indicate that the emulsifying properties of plant proteins (PLPs) can be improved after modification through covalent and/or non-covalent interactions with PPs due to the changes in the conformation and/or the surface chemistry of the proteins. Complexes formed between PLPs-PPs can serve as innovative ingredients for developing novel food products with modified textural properties. Also, Pickering emulsions, multiple emulsions, multilayer emulsions, nanoemulsions, and high internal phase emulsions can be stabilized by such systems to deliver bioactive compounds. This paper reviews the most recent research on the PLP-PP interactions and their role in the stabilization of various emulsion-based systems. A special emphasis is given to modifying the structure and functionality of PLPs and PPs. The challenges and opportunities of applying PLP-PP interactions in emulsion-based systems are also highlighted.

Effect of dynamic high-pressure microfluidization treatment on soybean protein isolate-rutin non-covalent complexes

In this investigation, soybean protein isolate-rutin (SPI-RT) complexes were treated using dynamic high-pressure microfluidization (DHPM). The effects of this process on the physicochemical and thermodynamic properties of SPI were investigated at different pressures. Fourier-transform infrared spectroscopy and fluorescence spectroscopy provided evidence that the SPI structure had been altered. The binding of SPI to RT resulted in a decrease in the percentage of α-helices and random curls as well as an increase in the percentage of β-sheets. In particular, the α-helix content decreased from 29.84 % to 26.46 %, the random curl content decreased from 17.45 % to 15.57 %, and the β-sheet content increased from 25.37 % to 26.53 %. Moreover, fluorescence intensity decreased, and the emission peak of the complex was red-shifted by 6 nm, exposing the internal groups. Based on fluorescence quenching analysis, optimal SPI-RT complexation was achieved after 120-MPa DHPM treatment, and molecular docking analysis verified the interaction between SPI and RT. The minimum particle size, maximum absolute potential, and total phenolic content of the complexes were 78.06 nm, 21.4 mV and 74.35 nmol/mg protein, respectively. Furthermore, laser confocal microscopy revealed that the complex particles had the best microstructure. Non-covalent interactions between the two were confirmed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Moreover, the hydrophobicity of the complex particle's surface increased to 16,045 after 120-MPa DHPM treatment. The results of this study suggest that DHPM strongly promotes the improvement of the physicochemical properties of SPI, and provide a theoretical groundwork for further research.

Physical treatment synergized with natural surfactant for improving gas-water interfacial behavior and foam characteristics of α-lactalbumin

The purpose of this study was to investigate effect of physical treatment (ultrasound, U/high pressure homogenization, H/combined treatment, UH or HU) and surfactant (Mogroside V, Mog) on air/water interface adsorption and foaming properties of α-lactalbumin (ALa). Firstly, the binding of Mog and all physical-treated ALa was a static quenching process. Mog had the greatest binding affinity for HU-ALa among all treated samples. U or H treatment could change surface hydrophobicity of ALa/Mog complex. Secondly, at the molar ratio (ALa:Mog) of 1:50, foaming ability (FA) of all ALa samples got the maximum. The sequence of FA in ALa and ALa/Mog complex was listed as follow: HU > U > H > UH. Moreover, foaming stability (FS) of HU-ALa was the highest, followed by H-ALa, U-ALa and UH-ALa. Meanwhile, low concentration Mog increased FS of ALa or UH-ALa, but it reduced FS of H-ALa, U-ALa and HU-ALa. Quartz crystal microbalance with dissipation monitoring (QCM-D) experiment indicated that ALa/Mog complex after U or H treatment was quickly absorbed at air/water interface, compared with the treated ALa, and HU-ALa/Mog had the largest frequency shift. In addition, HU-ALa had the thickest bubble membrane and the highest dissipation shift in all samples, indicating that the absorbed membrane thickness and viscoelasticity of samples was correlated with foam stability. Therefore, U and H treatment synergism with Mog was an effective approach to enhance foam properties of ALa, which indicated that HU-treated ALa/Mog complex could be viewed as the safe and efficient foaming agent applied in food processing.

Dynamic high pressure treatments: current advances on mechanistic-cum-transport phenomena approaches and plant protein functionalization

Dynamic high pressure treatment (DHPT) either by high pressure homogenization or microfluidisation, is an emerging concept used in the food industry for new products development through macromolecules modifications in addition to simple mixing and emulsification action. Mechanistic understanding of droplets breakup during high pressure homogenization is used to understand how these compact and high molecular weight-sized globular plant proteins are affected during DHPTs. Plant protein needs to be functionalized for advanced use in food formulation. DHPTs brought changes in plant proteins' secondary, tertiary, and quaternary structures through alterations in intermolecular and intramolecular interactions, sulfhydryl groups, and disulfide bonds. These structural changes in plant proteins affected their functional and physicochemical properties like solubility, oil and water holding capacity, gelation, emulsification, foaming, and rheological properties. These remarkable changes made utilization of this concept in novel food system applications like in plant-based dairy analogues. Overall, this review provides a comprehensive and critical understanding of DHPTs on their mechanistic and transport approaches for droplet breakup, structural and functional modification of plant macromolecules. This article also explores the potential of DHPT for formulating plant-based dairy analogues to meet healthy and sustainable food consumption needs. HIGHLIGHTSIt critically reviews high pressure homogenization (HPH) and microfluidisation (DHPM).It explores the mechanistic and transport phenomena approaches of HPH and DHPMHPH and DHPM can induce conformational and structural changes in plant proteins.Improvement in the functional properties of HPH and DHPM treated plant proteins.HPH and DHPM are potentially applicable for plant based dairy alternatives food system.