Current knowledge on the interfacial behaviour limits our understanding of plant protein functionality in emulsions

Plant-based whipping cream: A promising sustainable alternative to dairy products

Future food is dedicated to transforming the traditional production model of the food industry, making people and the planet healthier, and addressing the challenges facing humanity. The development of plant-based foods is one of the core contents of future food and an important way to achieve green and low-carbon development of the food industry. A prevailing food trend in the dairy industry is the demand to develop various plant-based alternatives to dairy products. Plant-based whipping cream is a complex emulsion-foam system that can be transformed from an oil-in-water emulsion structure to a triphasic (solid-liquid-gas) foam structure by whipping, which should achieve a subtle balance between emulsion stability, whipping destabilization, and foam re-stabilization. This review aims to understand the science and technology underlying the development of plant-based whipping cream. The initial focus is on the fundamental principle of stabilization and destabilization of plant-based whipping cream, as the development of successful products depends on understanding their physicochemical basis. Three main processing technologies for the manufacture of plant-based whipping cream are then introduced: homogenization, sterilization, and tempering. Besides that, the role of the basic ingredients in plant-based whipping cream is highlighted, including vegetable fats, plant proteins, low-molecular-weight emulsifiers, and thickeners. In order to quantify and compare the quality attributes of different plant-based whipping cream products under standardized conditions, we provide an overview of characterization methods to evaluate emulsion stability, whipping destabilization, and foam re-stabilization of plant-based whipping cream. Subsequently, the legislations and regulations related to plant-based whipping cream products are introduced to cater to their market development. Finally, the current challenges faced by plant-based whipping cream are highlighted. This review aims to provide a guidance for researchers and manufacturers in related industries.

Use of emulsifying plant protein hydrolysates from winery, whiskey and brewery by-products for the development of echium oil delivery emulsions

This study investigates the production of plant protein hydrolysates from defatted grape seed flour and barley spent grains, by-products of wine, beer and whiskey industries, using limited hydrolysis with subtilisin or trypsin. The hydrolysates were characterized by protein content, molecular weight, antioxidant capacity, interfacial adsorption, dilatational rheology, and interfacial conformational changes using synchrotron radiation circular dichroism. Physical and oxidative stability of 5 % echium oil-in-water emulsions (pH 7), stabilized by the hydrolysates, were studied during seven days of storage. The trypsin-derived hydrolysate from brewers' spent grains resulted in the most physically stable emulsion due to enhanced interfacial adsorption and higher dilatational modulus. Alternatively, the trypsin-treated grape seed flour hydrolysate provided the emulsion with the highest oxidative stability, aligning with its superior in vitro antioxidant capacity. These results show the potential of wine and brewery industry side streams as a sustainable source of plant-based emulsifiers with application in omega-3 delivery systems.

Effect of Ultrasound Time on Structural and Gelling Properties of Pea, Lupin, and Rice Proteins

Plant proteins are garnering interest due to the growing demand for plant-based products, but their functionality in gel-based foods remains limited. Ultrasound (US) technology may improve the technological properties of proteins. Thus, the effect of US treatment time (0-15 min) on the structure and gelling properties of pea, lupin, and rice proteins was evaluated. The results showed that the whiteness (~60%) of all freeze-dried proteins remained unchanged (p > 0.05), regardless of the US time. However, FT-IR analysis revealed progressive reductions in α-helix and β-sheet for pea and lupin proteins (~50%) with US time, indicating partial unfolding. In addition, microstructure analysis showed an ~80% reduction in aggregate size for these proteins, while rice protein exhibited minimal changes. Conversely, weak gels were formed with pea and lupin proteins treated after 5 and 10 min of US, respectively, whereas rice protein did not form gels. Furthermore, US treatment time significantly increased (p < 0.05) the mechanical moduli, resulting in more structured gels after longer treatment times (tan δ ~0.3 at 15 min of US). These findings suggest that US treatment enhances the gelling properties of pea and lupin proteins, making them more suitable for plant-based food applications such as yogurt or desserts.

Epigallocatechin-3-gallate improved rheological properties of rice bran protein-soybean protein isolate conjugates emulsions by regulating interface protein conformation

The effects of epigallocatechin-3-gallate (EGCG) on the conformation of interface-adsorbed protein (IAP) and interface-unadsorbed protein (IUAP) and rheological properties of rice bran protein-soybean protein isolate conjugates emulsions were investigated. The results showed that the viscosity, storage modulus, and loss modulus of conjugates emulsions initially increased, and subsequently declined as EGCG concentration increased (0 %-20 %), and reached the maximum value at an EGCG concentration of 10 %. Meanwhile, the absolute value of ζ-potential (-49.333 mV), average particle size (831.033 nm), and flexibility (0.052) of IAP reached the maximum at 10 % of EGCG. The absolute value of ζ-potential and surface hydrophobicity of IAP were higher than those of IUAP. Overall, moderate concentration of EGCG (10 %) enhanced the adsorption of highly flexible and highly surface-charged IAP at the oil-water interface and promoted the formation of a highly viscoelastic interfacial membrane, which improved the rheological properties of conjugates emulsions.

Thin liquid films stabilized by plant proteins: Implications for foam stability

HYPOTHESIS

Plant-based proteins offer a sustainable solution for stabilizing multiphase food materials like edible foams and emulsions. However, challenges in understanding and engineering plant protein-stabilized interfaces persist, mostly because of the commonly poorer functionality and complex composition of the respective protein isolates. We hypothesize that part of the limited understanding is related to the lack of experimental data on the length-scale of the thin liquid film that separates two neighboring bubbles. By conducting such experiments, we aim to better understand the mechanisms by which plant proteins stabilize foams, a critical material in food applications.

EXPERIMENTS

In this study, we employ the dynamic thin film balance method to study the equilibrium properties and dynamic drainage behavior of foam thin liquid films stabilized by proteins derived from two main plant protein sources, yellow peas and rapeseeds, to investigate potential differences in film stabilization.

FINDINGS

Our thin film results provide new insights into the general foam stabilization mechanism of the two plant proteins. Most studies in this field focus on the impact of surface rheological parameters on stability of plant protein-based foam. We show that for such foams the half-life scales linearly with film thickness, the latter being closely related to the steric and electrostatic interactions developed across the respective films in equilibrium. Our study demonstrates the value of thin film studies in complementing traditional methods for studying protein-stabilized interfaces and facilitates an understanding of foam stabilization mechanisms that are universal among various surface-active species.

Innovative applications of medium- and long-chain triacylglycerol in nutritional support: Current perspectives and future directions

As a unique structured lipid, medium- and long-chain triacylglycerol (MLCT) is characterized by the combination of medium- and long-chain fatty acids in a single triacylglycerol molecule. In recent years, MLCT, as a nutritional lipid, has gradually emerged as a research hot topic in the fields of food science and nutrition. This paper innovatively provides a comprehensive review of the current application status and development prospects of MLCT in nutritional support. First, the basic principles defining characteristics and selection basis of both enteral and parenteral nutrition are analyzed, elucidating the differences between the two modalities in terms of nutrient delivery pathway, absorption mechanisms, and physiological effects. Subsequently, the natural sources and artificial synthetic pathways of MLCT along with its metabolic behavior in vivo are elaborated. On this basis, the latest research advancements in the application of MLCT in both nutritional models are reviewed, with a particular emphasis on current research hotspots. Finally, the challenges encountered in the practical application of MLCT are discussed, and the future trajectory of MLCT as a functional lipid is predicted. In particular, the innovative potential of MLCT in functional foods, food for special medical purposes, personalized nutrition, and other aspects is emphasized, which provides beneficial ideas and directions for further research and industrial applications of MLCT.

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.

Interfacial and Bulk Properties of Potato and Faba Protein in Connection with Physical Emulsion Stability at Various pH Values and High Salt Concentrations

The protein transition motivates the use of plant proteins, but their application in food emulsions is challenging, especially when high concentrations of oil and salt are needed for formulation and sensory properties. In the present work, we connect the iso-electric point of two potato protein isolates (patatin-rich, POPI-200; protease inhibitor-rich, POPI-300) and a faba protein isolate (FPI) to the behavior in the bulk phase and at the interface, and relate this to the physical stability of 45 wt% oil-in-water (O/W) emulsions in the presence of NaCl at pH 4.0-7.0. In the absence of NaCl, a higher bulk viscosity was found at the iso-electric point (IEP), especially for the FPI. In the presence of NaCl, the viscosity of the POPI-200 solutions was highest, followed by POPI-300, and that of the FPI was lowest, irrespective of the pH. Both POPIs showed faster initial adsorption at the O/W interface in the absence of NaCl, and formed a more elastic layer compared to the FPI. For all proteins, salt addition leads to less elastic films. Interestingly, the interfaces were more elastic at a pH close to the IEP of the protein in the presence of NaCl. Both POPI-stabilized emulsions showed higher stability (smaller size and less oiling off) than the FPI-stabilized emulsions, which makes potato proteins relevant for food emulsion product formulation, even under high salt conditions.

Emulsions stabilized by pea protein-rich ingredients as an alternative to dairy proteins for food sustainability: Unveiling the key role of pea endogenous lipids in the surface-induced crystallization of milk fat

In the current context of food transition, the growing demand of consumers for sustainable plant-based protein sources has stimulated interest of food scientists in plant protein ingredients as alternatives to dairy protein ingredients. In this study, we hypothesized that the crystallization properties of dairy emulsions could be affected by the chemical complexity of commercially available pea protein-rich ingredients that contain proteins but also endogenous lipids. Dairy emulsions (30 %wt milk fat) stabilized either by a pea protein isolate or dairy proteins were prepared, their microstructure and interfacial composition were characterized. The crystallization and melting properties of milk fat in anhydrous state and in the emulsions were examined by the combination of differential scanning calorimetry (DSC) and synchrotron-radiation X-ray diffraction as a function of temperature (SR-XRDT). The results revealed differences in the milk fat crystallization properties in emulsion as a function of the ingredient used and highlighted a specific role played by pea endogenous lipids. The pea protein-rich ingredient contained 12.1 %wt endogenous lipids including 56.2 %wt polar lipids, 40.7 %wt triacylglycerols (TAGs) and 3.1 %wt plant sterols. The partitioning of pea endogenous lipids occurred upon emulsion formation as a function of their polarity: liquid unsaturated fatty acid rich pea TAGs mixed with milk TAGs in the core of the lipid droplets while pea polar lipids migrated at the TAGs/water interface together with pea proteins. Pea polar lipids were composed of saturated high melting temperature (Tm) and unsaturated low Tm molecular species. High Tm pea polar lipids exhibited a phase transition on cooling (from Lα/expansed to Lβ/condensed) and acted as interfacial templates for surface heterogeneous nucleation and crystal growth of high crystallization temperature milk TAGs. The key interfacial and functional roles played by pea endogenous lipids present in the protein isolate were demonstrated. This study highlights the importance to examine the chemical composition and the properties of plant-based ingredients that are increasingly used for sustainable food formulations.

Interaction of dairy and plant proteins for improving the emulsifying and gelation properties in food matrices: a review

A variety of variables influence food texture, two of which are gelation and emulsification. Protein interactions have an important role in influencing gelation and emulsifying properties. The utilization of plant proteins in the development of food systems is a prominent subject within the current protein transition paradigm. Plant proteins diminish gel strength compared to dairy proteins. Protein providers prefer to create their own networks rather than rely on tight ties. It may be feasible to resolve these challenges if the interactions between plant and dairy proteins are known at all sizes, from molecular to macroscopic. Therefore, the proteins and dairy proteins are the main emphasis of this review. The role of these proteins in interacting with food matrices is also discussed. Additionally, this data gives information on worldwide research trends. Finally, a glimpse into the future was discussed.

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.

Application of legumes in plant-based milk alternatives: a review of limitations and solutions

In recent years, a global shift has been observed toward reducing the consumption of animal-derived foods in favor of healthier and more sustainable dietary choices. This has led to a steady growth in the market for plant-based milk alternatives (PBMAs). Projections suggest that this market will reach a value of USD 69.8 billion by 2030. Legumes, being traditional and nutritious ingredients for PMBAs, are rich in proteins, dietary fibers, and other nutrients, with potential health benefits such as anticancer and cardiovascular disease prevention. In this review, the application of 12 legumes in plant-based milk alternatives was thoroughly discussed for the first time. However, compared to milk, processing of legume-based beverages can lead to deficiencies such as nutritional imbalance, off-flavor, and emulsion stratification. Considering the potential and challenges associated with legume-based beverages, this review aims to provide a scientific comparison between legume-based beverages and cow's milk in terms of nutritional quality, organoleptic attributes and stability, and to summarize ways to improve the deficiencies of legume-based beverages in terms of raw materials and processing method improvements. In conclusion, the legume-based beverage industry will be better enhanced and developed by improving the issues.

Lipid oxidation in emulsions: New insights from the past two decades

Lipid oxidation constitutes the main source of degradation of lipid-rich foods, including food emulsions. The complexity of the reactions at play combined with the increased demand from consumers for less processed and more natural foods result in additional challenges in controlling this phenomenon. This review provides an overview of the insights acquired over the past two decades on the understanding of lipid oxidation in oil-in-water (O/W) emulsions. After introducing the general structure of O/W emulsions and the classical mechanisms of lipid oxidation, the contribution of less studied oxidation products and the spatiotemporal resolution of these reactions will be discussed. We then highlight the impact of emulsion formulation on the mechanisms, taking into consideration the new trends in terms of emulsifiers as well as their own sensitivity to oxidation. Finally, novel antioxidant strategies that have emerged to meet the recent consumer's demand will be detailed. In an era defined by the pursuit of healthier, more natural, and sustainable food choices, a comprehensive understanding of lipid oxidation in emulsions is not only an academic quest, but also a crucial step towards meeting the evolving expectations of consumers and ensuring the quality and stability of lipid-rich food products.

Effects of glycation method on the emulsifying performance and interfacial behavior of coconut globulins-fucoidan complexes

Coconut globulins (CG) possesses potential as an emulsifier but has not been utilized well. In this study, the emulsifying performance of glycated CG-fucoidan (CGF) complexes, and the relationship between emulsifying stability and interfacial behavior were investigated. The results showed that the grafting of fucoidan increased the molecular weight of CG, and decreased the zeta potential and fluorescence intensity. With the higher glycosylation degree, the fucoidan modified CG exhibited better emulsifying stability and higher viscosity. Moreover, the result of adsorption kinetics revealed that elasticity was the main property of the interface layer. Compared to CG, CGF complexes with high degree of glycosylation had thicker interfacial layer on the oil-water interface. A thicker elastic interfacial layer may be beneficial to the emulsion stability, owing to the strong interaction of electrostatic repulsion and steric hindrance between oil droplets. These findings may provide useful information for glycated CGF complexes as emulsifiers in functional food.

Enhancing the textural and rheological properties of fermentation-induced pea protein emulsion gels with transglutaminase

The aim of this study was to assess how transglutaminase (TG) impacts the microstructure, texture, and rheological properties of fermentation-induced pea protein emulsion gels. Additionally, the study examined the influence of storage time on the functional properties of these gels. Fermentation-induced pea protein gels were produced in the presence or absence of TG and stored for 1, 4, 8, 12, and 16 weeks. Texture analysis, rheological measurements, moisture content and microstructure evaluation with confocal laser scanning microscopy (CLSM) and 3D image analysis were conducted to explore the effects of TG on the structural and rheological properties of the fermented samples. The porosity of the protein networks in the pea gels decreased in the presence of TG, the storage modulus increased and the textural characteristics were significantly improved, resulting in harder and more springy gels. The gel porosity increased in gels with and without TG after storage but the effect of storage on textural and rheological properties was limited, indicating limited structural rearrangement once the fermentation-induced pea protein emulsion gels are formed. Greater coalescence was observed for oil droplets within the gel matrix after 16 weeks of storage in the absence of TG, consistent with these protein structures being weaker than the more structurally stable TG-treated gels. This study shows that TG treatment is a powerful tool to enhance the textural and rheological properties of fermentation-induced pea protein emulsion gels.

Enhanced stabilization of oil-in-water (O/W) emulsions by fibrillar gel particles from lentil proteins

Pulse proteins as a sustainable protein source have attracted increasing interest in food development, but pulse proteins are generally less surface active than dairy proteins. This work introduces lentil protein (LP)-based fibrillar gel particles (FGPs) fabricated from heat-induced LP fibrillar aggregates by 1, 4, 8, and 16 h of heating, followed by particle reduction using sonication. The heating time significantly impacts the FGPs particle size and surface hydrophobicity. The FGP prepared by 4 h of heating (FGP-4) showed a small size (<200 nm) and homogeneous size distribution while possessing significantly increased surface hydrophobicity compared to untreated LP. Such structural features made FGP-4 better adsorb at the O/W interface and then completely covered the oil droplet surface, leading to homogeneous emulsions of small size (22.33 μm) and superior long-term stability without creaming for 30 days. In addition, the dispersed FGP in the bulk phase could develop interactions among each other, leading to improved emulsion viscosity and texture without oil droplet size change. This finding suggests that constructing fibril-type gel particles can provide a new strategy for forming superior O/W emulsions with improved stability from plant proteins.

Novel Milk Substitute Based on Pea, Bean and Sunflower Seeds with Natural Bioactive Stabilisers

The aim of this research was to create a plant-based beverage based on seeds of sunflower (Helianthus annuus), pea (Pisum sativum) and runner bean (Phaseolus multiflorus). The selection of the ingredients was based on the main objective to obtain the nutritional value and sensory characteristics of a formed product similar to cow's milk. The ingredient proportions were created by comparing the protein, fat and carbohydrate content of seeds versus cow's milk. Due to the observed low long-term stability of plant-seed-based drinks, a water binding guar gum, a thickener in the form of locust bean gum and gelling citrus amidated pectin containing dextrose were added and evaluated as functional stabilisers. All of the designed and created systems were subjected to selected methods of characterisation of the most important final product properties, such as rheology, colour, emulsion and turbidimetric stability. Rheological analysis confirmed the highest stability of the variant supplemented with 0.5% guar gum. Both stability and colour measurements indicated the positive characteristics of the system supplemented with 0.4% pectin. Finally, the product with 0.5% guar gum was identified as the most distinctive and similar vegetable drink to cow's milk.

Plant protein-based emulsions for the delivery of bioactive compounds

Emulsion-based delivery systems (EBDSs) can be used as effective carriers for bioactive compounds (bioactives). Recent studies have shown that plant proteins (PLPs) have the potential to be utilized as stabilizers of emulsions for loading, protection and delivery of bioactives. Different strategies combining physical, chemical and biological techniques can be applied for alteration of the structural characteristics and improving the emulsification and encapsulation performance of PLPs. The stability, release, and bioavailability of the encapsulated bioactives can be tailored via optimizing the processing conditions and formulation of the emulsions. This paper presents cutting-edge information on PLP-based emulsions carrying bioactives in terms of their preparation methods, physicochemical characteristics, stability, encapsulation efficiency and release behavior of bioactives. Strategies applied for improvement of emulsifying and encapsulation properties of PLPs used in EBDSs are also reviewed. Special emphasis is given to the use of PLP-carbohydrate complexes for stabilizing bioactive-loaded emulsions.

Food Emulsion Gels from Plant-Based Ingredients: Formulation, Processing, and Potential Applications

Recent advances in the understanding of formulations and processing techniques have allowed for greater freedom in plant-based emulsion gel design to better recreate conventional animal-based foods. The roles of plant-based proteins, polysaccharides, and lipids in the formulation of emulsion gels and relevant processing techniques such as high-pressure homogenization (HPH), ultrasound (UH), and microfluidization (MF), were discussed in correlation with the effects of varying HPH, UH, and MF processing parameters on emulsion gel properties. The characterization methods for plant-based emulsion gels to quantify their rheological, thermal, and textural properties, as well as gel microstructure, were presented with a focus on how they can be applied for food purposes. Finally, the potential applications of plant-based emulsion gels, such as dairy and meat alternatives, condiments, baked goods, and functional foods, were discussed with a focus on sensory properties and consumer acceptance. This study found that the implementation of plant-based emulsion gel in food is promising to date despite persisting challenges. This review will provide valuable insights for researchers and industry professionals looking to understand and utilize plant-based food emulsion gels.

Pea and Soy Protein Stabilized Emulsions: Formulation, Structure, and Stability Studies

During the last decades, there has been a huge consumer concern about animal proteins that has led to their replacement with plant proteins. Most of those proteins exhibit emulsifying properties; thus, the food industry begins their extensive use in various food matrices. In the present study, pea and soy protein isolates (PPI and SPI) were tested as potential candidates for stabilizing food emulsions to encapsulate α-tocopherol and squalene. More specifically, PPI and SPI particles were formulated using the pH modification method. Following, emulsions were prepared using high-shear homogenization and were observed at both a microscopic and macroscopic level. Furthermore, the adsorption of the proteins was measured using the bicinchoninic acid protein assay. The emulsions’ droplet size as well as their antioxidant capacity were also evaluated. It was found that the droplet diameter of the SPI-based emulsions was 60.0 μm, while the PPI ones had a relatively smaller diameter of approximately 57.9 μm. In the presence of the bioactives, both emulsions showed scavenging activity of the 2,20-Azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical cation (ABTS·+) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, with the ones loaded with α-tocopherol having the greatest antioxidant capacity. Overall, the proposed systems are very good candidates in different food matrices, with applications ranging from vegan milks and soups to meat alternative products.

Current Status and Nutritional Value of Green Leaf Protein

Green leaf biomass is one of the largest underutilized sources of nutrients worldwide. Whether it is purposely cultivated (forage crops, duckweed) or upcycled as a waste stream from the mass-produced agricultural crops (discarded leaves, offcuts, tops, peels, or pulp), the green biomass can be established as a viable alternative source of plant proteins in food and feed processing formulations. Rubisco is a major component of all green leaves, comprising up to 50% of soluble leaf protein, and offers many advantageous functional features in terms of essential amino acid profile, reduced allergenicity, enhanced gelation, foaming, emulsification, and textural properties. Nutrient profiles of green leaf biomass differ considerably from those of plant seeds in protein quality, vitamin and mineral concentration, and omega 6/3 fatty acid profiles. Emerging technological improvements in processing fractions, protein quality, and organoleptic profiles will enhance the nutritional quality of green leaf proteins as well as address scaling and sustainability challenges associated with the growing global demand for high quality nutrition.

Multiscale combined techniques for evaluating emulsion stability: A critical review

Emulsions are multiscale and thermodynamically unstable systems which will undergo various unstable processes over time. The behavior of emulsifier molecules at the oil-water interface and the properties of the interfacial film are very important to the stability of the emulsion. In this paper, we mainly discussed the instability phenomena and mechanisms of emulsions, the effects of interfacial films on the long-term stability of emulsions and summarized a set of systematic multiscale combined methods for studying emulsion stability, including droplet size and distribution, zeta-potential, the continuous phase viscosity, adsorption mass and thickness of the interfacial film, interfacial dilatational rheology, interfacial shear rheology, particle tracking microrheology, visualization technologies of the interfacial film, molecular dynamics simulation and the quantitative evaluation methods of emulsion stability. This review provides the latest research progress and a set of systematic multiscale combined techniques and methods for researchers who are committed to the study of oil-water interface and emulsion stability. In addition, this review has important guiding significances for designing and customizing interfacial films with different properties, so as to obtain emulsion-based delivery systems with varying stability, oil digestibility and bioactive substance utilization.

Comparative Composition Structure and Selected Techno-Functional Elucidation of Flaxseed Protein Fractions

This study aimed to comparatively elucidate the composition structure and techno-functionality of flaxseed protein isolate (FPI), globulin (FG), and albumin (FA) fractions. The results showed that FA possessed smaller particle dimensions and superior protein solubility compared to that of FG (p < 0.05) due to the lower molecular weight and hydrophobicity. FA and FG manifested lamellar structure and nearly spherical morphology, respectively, whereas FPI exhibited small lamellar strip structure packed by the blurring spheres. The Far-UV CD, FTIR spectrum, and intrinsic fluorescence confirmed more flexible conformation of FA than that of FG, followed by FPI. The preferential retention of free phenolic acids was observed for FA, leading to excellent antioxidant activities compared with that of FG in FPI (p < 0.05). FA contributed to the foaming properties of FPI, relying on the earlier interfacial adsorption and higher viscoelastic properties. FA displayed favorable emulsifying capacity but inferior stability due to the limited interfacial adsorption and deformation, as well as loose/porous interface. By comparison, an interlayer anchoring but no direct interface coating was observed for lipid droplets constructed by FG, thereby leading to preferable emulsion stability. However, FPI produced lipid droplets with dense interface owing to the effective migration of FA and FG from bulk phase, concomitant with the easy flocculation and coalescence. Thus, the techno-functionality of flaxseed protein could be tailed by modulating the retention of albumin fraction and specific phenolic acids.

Effects of pH and Ionic Salts on the Emulsifying and Rheological Properties of Acorn Protein Isolate

This study was designed to evaluate the emulsifying and rheological properties of acorn protein isolate (API) in different pH mediums (pH 3, 7 and 9) and in the presence of ionic salts (1 M NaCl and 1 M CaCl2). API shows higher solubility in distilled water at pH 7, while at the same pH, a decrease in solubility was observed for API in the presence of CaCl2 (61.30%). A lower emulsifying activity index (EAI), lower stability index (ESI), larger droplet sizes and slight flocculation were observed for API in the presence of salts at different pHs. Importantly, CaCl2 treated samples showed relevantly higher EAI (252.67 m2/g) and ESI (152.67 min) values at all pH as compared to NaCl (221.76 m2/g), (111.82 min), respectively. A significant increase in interfacial protein concentration (4.61 mg/m2) was observed for emulsion at pH 9 with CaCl2, while the major fractions of API were observed in an interfacial layer after SDS-PAGE analysis. All of the emulsion shows shear thinning behavior (τc > 0 and n < 1), while the highest viscosity was observed for emulsion prepared with CaCl2 at pH 3 (11.03 ± 1.62). In conclusion, API, in the presence of ionic salts at acidic, neutral and basic pH, can produce natural emulsions, which could be substitutes for synthetic surfactants for such formulations.