Cereal protein-based nanoparticles as agents stabilizing air–water and oil–water interfaces in food systems

Advances of protein-based emulsion gels as fat analogues: Systematic classification, formation mechanism, and food application

Fat plays a pivotal role in the appearance, flavor, texture, and palatability of food. However, excessive fat consumption poses a significant risk for chronic ailments such as obesity, hypercholesterolemia, and cardiovascular disease. Therefore, the development of green, healthy, and stable protein-based emulsion gel as an alternative to traditional fats represents a novel approach to designing low-fat food. This paper reviews the emulsification behavior of proteins from different sources to gain a comprehensive understanding of their potential in the development of emulsion gels with fat-analog properties. It further investigates the emulsifying potential of protein combined with diverse substances. Then, the mechanisms of protein-stabilized emulsion gels with fat-analog properties are discussed, mainly involving single proteins, proteins-polysaccharides, as well as proteins-polyphenols. Moreover, the potential applications of protein emulsion gels as fat analogues in the food industry are also encompassed. By combining natural proteins with other components such as polysaccharides, polyphenols, or biopolymers, it is possible to enhance the stability of the emulsion gels and improve its fat-analog texture properties. In addition to their advantages in protecting oil oxidation, limiting hydrogenated oil intake, and delivering bioactive substances, protein-based emulsion gels have potential in food 3D printing and the development of specialty fats for plant-based meat.

Toward Diverse Plant Proteins for Food Innovation

This review highlights the development of plant proteins from a wide variety of sources, as most of the research and development efforts to date have been limited to a few sources including soy, chickpea, wheat, and pea. The native structure of plant proteins during production and their impact on food colloids including emulsions, foams, and gels are considered in relation to their fundamental properties, while highlighting the recent developments in the production and processing technologies with regard to their impacts on the molecular properties and aggregation of the proteins. The ability to quantify structural, morphological, and rheological properties can provide a better understanding of the roles of plant proteins in food systems. The applications of plant proteins as dairy and meat alternatives are discussed from the perspective of food structure formation. Future directions on the processing of plant proteins and potential applications are outlined to encourage the generation of more diverse plant-based products.

Microwave radiation induces modifications in the protein fractions of tef flours and modulates their derived techno-functional properties

The impact of microwave (MW) treatments on the structure, solubility, and techno-functional properties of the proteins in starchy matrices is still poorly understood. This study aimed to investigate the effects of MW intensity by applying 1, 2, and 6 min of radiation on two tef flour varieties moistened at 15 % and 25 %. The fractionation method recovered ∼83 % of the total protein content in untreated flours. The interaction between treatment time and moisture content (MC) significantly influenced the extraction of protein fractions. Samples treated at 25 %MC showed significant reductions in albumins (up to -74 %), globulins (up to -79 %), and prolamins (up to -32 %). The SDS-extractable proteins of both tef flours presented similar molecular weights (12-100 kDa). SDS-PAGE analysis revealed decreased band intensity in MW-treated samples compared to untreated flours, and confocal analysis showed changes in the native state of proteins in treated samples. Shorter treatments at low MC significantly improved the emulsifying stability of tef flours, particularly in brown tef flour, with an enhancement of up to 203 %. The hydration properties significantly increased in flours treated at 25 %MC for 6 min. Pearson correlation analysis demonstrated the influence of treatment time and MC on protein recovery and functional properties of tef flours.

Relevance of the air-water interfacial and foaming properties of (modified) wheat proteins for food systems

A shift from animal protein- to plant protein-based foods is crucial in transitioning toward a more sustainable global food system. Among food products typically stabilized by animal proteins, food foams represent a major category. Wheat proteins are ubiquitous and structurally diverse, which offers opportunities for exploiting them for food foam and air-water interface stabilization. Notably, they are often classified into those that are soluble in aqueous systems (albumins and globulins) and those that are not (gliadins and glutenins). However, gliadins are at least to an extent water extractable and thus surface active. We here provide a comprehensive overview of studies investigating the air-water interfacial and foaming properties of the different wheat protein fractions. Characteristics in model systems are related to the functional role that wheat proteins play in gas cell stabilization in existing wheat-based foods (bread dough, cake batter, and beer foam). Still, to further extend the applicability of wheat proteins, and particularly the poorly soluble glutenins, to other food foams, their modification is required. Different physical, (bio)chemical, and other modification strategies that have been utilized to alter the solubility and therefore the air-water interfacial and foaming properties of the gluten protein fraction are critically reviewed. Such approaches may open up new opportunities for the application of (modified) gluten proteins in other food products, such as plant-based meringues, whippable drinks, or ice cream. In each section, important knowledge gaps are highlighted and perspectives for research efforts that could lead to the rational design of wheat protein systems with enhanced functionality and overall an increased applicability in food industry are proposed.

Protein Nanoparticles: Uniting the Power of Proteins with Engineering Design Approaches

Protein nanoparticles, PNPs, have played a long-standing role in food and industrial applications. More recently, their potential in nanomedicine has been more widely pursued. This review summarizes recent trends related to the preparation, application, and chemical construction of nanoparticles that use proteins as major building blocks. A particular focus has been given to emerging trends related to applications in nanomedicine, an area of research where PNPs are poised for major breakthroughs as drug delivery carriers, particle-based therapeutics or for non-viral gene therapy.

Recent Developments in the Formulation and Use of Polymers and Particles of Plant-based Origin for Emulsion Stabilizations

The main scope of this Review was the recent progress in the use of plant-based polymers and particles for the stabilization of Pickering and non-Pickering emulsion systems. Due to their availability and promising performance, it was discussed how the source, modification, and formulation of cellulose, starch, protein, and lignin-based polymers and particles would impact their emulsion stabilization. Special attention was given toward the material synthesis in two forms of polymeric surfactants and particles and the corresponding formulated emulsions. Also, the effects of particle size, degree of aggregation, wettability, degree of substitution, and electrical charge in stabilizing oil/water systems and micro- and macro-structures of oil droplets were discussed. The wide range of applications using such plant-based stabilizers in different technologies as well as their challenge and future perspectives were described.

Properties and Applications of Nanoparticles from Plant Proteins

Nanoparticles from plant proteins are preferred over carbohydrates and synthetic polymeric-based materials for food, medical and other applications. In addition to their large availability and relatively low cost, plant proteins offer higher possibilities for surface modifications and functionalizing various biomolecules for specific applications. Plant proteins also avoid the immunogenic responses associated with the use of animal proteins. However, the sources of plant proteins are very diverse, and proteins from each source have distinct structures, properties and processing requirements. While proteins from corn (zein) and wheat (gliadin) are soluble in aqueous ethanol, most other plant proteins are insoluble in aqueous conditions. Apart from zein and gliadin nanoparticles (which are relatively easy to prepare), soy proteins, wheat glutenin and proteins from several legumes have been made into nanoparticles. The extraction of soluble proteins, hydrolyzing with alkali and acids, conjugation with other biopolymers, and newer techniques such as microfluidization and electrospraying have been adopted to develop plant protein nanoparticles. Solid, hollow, and core-shell nanoparticles with varying sizes and physical and chemical properties have been developed. Most plant protein nanoparticles have been used as carriers for drugs and as biomolecules for controlled release applications and for stabilizing food emulsions. This review provides an overview of the approaches used to prepare nanoparticles from plant proteins, and their properties and potential applications. The review's specific focus is on the preparation methods and applications, rather than the properties of the proteins, which have been reported in detail in other publications.

Wet-etched asymmetric spherical nanoparticles with controllable pit structures and application in non-aqueous foams

The structure of colloidal particles is one of the factors that significantly affect their properties. Asymmetrical spherical particles with pit structures were prepared by using NH₄F to perform wet chemical etching on the designated positions of the partially masked particles. The depth and effectiveness of the pits were adjusted by varying the etching time. By changing the properties of the oil mixture, the oil repellency and foaming ability of the etched particles were characterized and compared. By controlling the wet etching time, the effective pit structures were etched on the particles. Within 10 d of being etched, the particles with pit geometry showed better foam properties than the original unetched particles. The pit structure on the particles improves the oil repellency of the particles in a series of oil mixtures with relatively lower surface tension. No significant difference was observed between the under-etched (18 h) particles and the non-etched particles. The ineffective geometry of the over-etched (15 d) particles results in insufficient robustness of the Cassie-Baxter state of the particles and reduces the volume of the generated foam.

Exploiting the potential of Sudanese sorghum landraces in biofortification: Physicochemical quality of the grain of sorghum (Sorghum bicolor L. Moench) landraces

This study aimed to describe the phytonutrients and antioxidant activity, protein content, in vitro protein digestibility (IVPD), protein fraction, and bioavailability of Fe and Zn in the grains of five sorghum landraces grown in Sudan. The results showed significant differences in all quality tests among the landraces. The Tetron landrace showed the highest percentage of crude protein and IVPD among the landraces. Additionally, most of the landrace grains had high contents of Fe and Zn with a high rate of bioavailability. The Kolom 4055 and Wad akar exhibited significantly higher total phenolic contents, with antioxidant activity of 79.3% and 83.4%, respectively. The glutelin content was relatively higher compared to the other fractions, irrespective of sorghum landraces. The principal components cumulatively accounted for 89.3% of the total variation among the five sorghum landraces. It can be concluded that these landraces could be used in the improvement of new value-added crops using the by-products of sorghum grains.

Food Protein-Based Nanodelivery Systems for Hydrophobic and Poorly Soluble Compounds

The hydrophobicity of bioactive molecules poses a considerable problem in the pharmaceutical and the food industry. Using food-based protein nanocarriers is one promising way to deliver hydrophobic molecules. These types of protein possess many functional properties such as surface activity, water-binding capacity, emulsification, foaming, gelation, and antioxidant activity, as well as their incorporation in the food industry as ingredients. Besides, they express low toxicity, are less expensive compared to synthetic polymers, and are biodegradable. This review aims to give a brief overview of the recent studies done using food proteins as colloidal delivery systems for hydrophobic and poorly soluble compounds.

Interaction between soyasaponin and soy β-conglycinin or glycinin: Air-water interfacial behavior and foaming property of their mixtures

The interaction between soyasaponin and soy β-conglycinin (7S) or glycinin (11S), adsorption of their mixtures at air-water interface, and foaming properties of the mixed system were investigated in this study. Fluorescence spectroscopy results showed that there was a weak binding of soyasaponin with 7S or 11S in bulk solutions, leading to the conformational changes of protein by nonspecific hydrophobic interactions. Dynamic surface properties of soyasaponin-7S/11S mixtures indicated that the composite layers formed via their weak interactions due to the synergy of reducing surface tension and the plateau of elasticity at the interface. Most mixtures represented high foam forming ability and stability except 0.2 % soyasaponin mixture, which could be a consequence that the surface behavior was dominated by soyasaponin under this concentration, and low surface elasticity lead to a less stable interfacial film. Overall, foamability of soyasaponin-7S mixtures were better than 11S ones. All data of this work was helpful to understand air-water behaviors of soyasaponin-7S/11S mixtures. This mixed system has shown good potential for further foam related industrial applications.

Use and Understanding of the Role of Spontaneously Formed Nanocellulosic Fiber from Lime (Citrus aurantifolia Swingle) Residues to Improve Stability of Sterilized Coconut Milk

Feasibility of using nanocellulosic fiber (NF) from lime residues as a stabilizer for oil-in-water emulsion was investigated. One-step process to simultaneously prepare an emulsion and NF is proposed. NF could spontaneously form by adding appropriately prepared fiber powder into the test emulsion viz. coconut milk, which was subsequently subject to homogenization and sterilization. Properties of the samples, that is, microstructure, rheological properties, emulsion stability, and color, after sterilization and after 8-week storage at 30 °C were determined. Sterilized samples exhibited pseudoplastic behavior. Samples containing higher NF concentrations exhibited higher viscosity; viscosity remained constant throughout the whole storage period. High emulsion stabilities (>97%) were observed for samples containing 0.4 to 0.8% (w/v) of NF. L^* , C^* , and h^* of the samples were 79 to 80, 8 to 10, and 90, respectively. Three-dimensional network of NF (diameters < 50 nm) attached to fat globule surfaces formed during homogenization is postulated to help stabilize the emulsions. PRACTICAL APPLICATION: One-step process to simultaneously prepare oil-in-water emulsion as well as nanocellulosic fiber (NF) is proposed. Such a formed NF can serve as natural ingredient to stabilize the emulsion. The proposed procedures should be of great interest to an industry producing oil-in-water emulsions (for example, canned coconut milk) that is looking for a natural alternative to synthetic stabilizer.