The effect of denaturation degree of protein on the microstructure, rheology and physical stability of oil-in-water (O/W) emulsions stabilized by whey protein isolate

Properties regulation and mechanism on ferritin/chitooligosaccharide dual-compartmental emulsions and its application for co-encapsulation of curcumin and quercetin bioactive compounds

Dual-compartmental emulsions, containing multiple chambers, possess great advantages in co-encapsulation of different cargoes. Herein, we reported a stable dual-compartmental emulsion by regulating the ratio of Marsupenaeus japonicus ferritin (MF) and chitooligosaccharide (COS), enabling efficient co-encapsulation of different compounds. The adsorption behavior of MF/COS complex over droplet interface varied at different ratios, thereby exerting an influence on the emulsion properties. Remarkably, emulsions stabilized by MF/COS complex at a ratio of 2:1 exhibited superior stability, as evidenced by no significant creaming or demulsification during storage or heat treatment. The mechanism is that MF/COS2:1 complex can enhance the formation of thicker interfacial layer and dense continuous phase network structure. Additionally, curcumin and quercetin can be co-encapsulated into the emulsions and their retention rates were significantly improved than those in oils, implying the potential of the resulting dual-compartmental emulsions in co-encapsulation and delivery of bioactive compounds.

New Insight into Food-Grade Emulsions: Candelilla Wax-Based Oleogels as an Internal Phase of Novel Vegan Creams

Cream-type emulsions containing candelilla wax-based oleogels (EC) were analyzed for their physicochemical properties compared to palm oil-based creams (EP). The microstructure, rheological behavior, stability, and color of the creams were determined by means of non-invasive and invasive techniques. All the formulations exhibited similar color parameters in CIEL*a*b* space, unimodal-like size distribution of lipid particles, and shear-thinning properties. Oleogel-based formulations were characterized by higher viscosity (consistency index: 172-305 mPa·s, macroscopic viscosity index: 2.19-3.08 × 10-5 nm-2) and elasticity (elasticity index: 1.09-1.45 × 10-3 nm-2), as well as greater resistance to centrifugal force compared to EP. Creams with 3, 4, or 5% wax (EC3-5) showed the lowest polydispersity indexes (PDI: 0.80-0.85) 24 h after production and the lowest instability indexes after environmental temperature changes (heating at 90 °C, or freeze-thaw cycle). EC5 had particularly high microstructural stability. In turn, candelilla wax content ≥ 6% w/w accelerated the destabilization processes of the cream-type emulsions due to disintegration of the interfacial layer by larger lipid crystals. It was found that candelilla wax-based lipids had great potential for use as palm oil substitutes in the development of novel vegan cream analogues.

The influence of α and α' subunits on SPI Pickering emulsions based on natural hybrid breeding varieties

In this study, food-grade protein nanoparticles (Wild-NPs, α-lack-NPs, α'-lack-NPs, and (α + α')-lack-NPs) were organized as emulsion stabilizers via thermal induction. The effects of α and α' subunits in soybean protein isolate (SPI) on Wild nanoparticle Pickering emulsion (Wild-NPPEs), α-lack nanoparticle Pickering emulsion (α-lack-NPPEs), α'-lack nanoparticle Pickering emulsion (α'-lack-NPPEs) and (α + α')-lack nanoparticle Pickering emulsion ((α + α')-lack-NPPEs) were investigated. The Pickering emulsion stabilization mechanism indicated that the α'-lack-NPs particle size, surface hydrophobicity, and contact angle were mostly comparatively large. Therefore, the absence of the α' subunit made the desorption of protein nanoparticles at the oil and water interface require higher energy. Through the hydrophobic interaction between molecules, the structure and properties of the emulsion were improved, showing good stability. The existence of α'-lack-NPPEs leads to the formation of a gel-like network in the emulsion, which increases the viscosity of the emulsion and makes the network structure of the emulsion more uniform and denser.

Impact of Cavitation Jet on the Structural, Emulsifying Features and Interfacial Features of Soluble Soybean Protein Oxidized Aggregates

A cavitation jet can enhance food proteins' functionalities by regulating solvable oxidized soybean protein accumulates (SOSPI). We investigated the impacts of cavitation jet treatment on the emulsifying, structural and interfacial features of soluble soybean protein oxidation accumulate. Findings have shown that radicals in an oxidative environment not only induce proteins to form insoluble oxidative aggregates with a large particle size and high molecular weight, but also attack the protein side chains to form soluble small molecular weight protein aggregates. Emulsion prepared by SOSPI shows worse interface properties than OSPI. A cavitation jet at a short treating time (<6 min) has been shown to break the core aggregation skeleton of soybean protein insoluble aggregates, and insoluble aggregates into soluble aggregates resulting in an increase of emulsion activity (EAI) and constancy (ESI), and a decrease of interfacial tension from 25.15 to 20.19 mN/m. However, a cavitation jet at a long treating time (>6 min) would cause soluble oxidized aggregates to reaggregate through an anti-parallel intermolecular β-sheet, which resulted in lower EAI and ESI, and a higher interfacial tension (22.44 mN/m). The results showed that suitable cavitation jet treatment could adjust the structural and functional features of SOSPI by targeted regulated transformation between the soluble and insoluble components.

Structural and Physicochemical Characterization of Extracted Proteins Fractions from Chickpea (Cicer arietinum L.) as a Potential Food Ingredient to Replace Ovalbumin in Foams and Emulsions

Chickpeas are the third most abundant legume crop worldwide, having a high protein content (14.9-24.6%) with interesting technological properties, thus representing a sustainable alternative to animal proteins. In this study, the surface and structural properties of total (TE) and sequential (ALB, GLO, and GLU) protein fractions isolated from defatted chickpea flour were evaluated and compared with an animal protein, ovalbumin (OVO). Differences in their physicochemical properties were evidenced when comparing TE with ALB, GLO, and GLU fractions. In addition, using a simple and low-cost extraction method it was obtained a high protein yield (82 ± 4%) with a significant content of essential and hydrophobic amino acids. Chickpea proteins presented improved interfacial and surface behavior compared to OVO, where GLO showed the most significant effects, correlated with its secondary structure and associated with its flexibility and higher surface hydrophobicity. Therefore, chickpea proteins have improved surface properties compared to OVO, evidencing their potential use as foam and/or emulsion stabilizers in food formulations for the replacement of animal proteins.

Spray-Dried Infant Formula Emulsion Stability as Affected by Pre-Heat Treatment and Total Solids Content of the Feed

Pre-spray-drying processing may affect stability after reconstitution of emulsion-based powders, such as infant formulas. This study aimed to evaluate the effects of pasteurization temperature and total solids (TS) of the feed on the stability of the emulsions obtained from the reconstituted powders. Four infant formula powders (50%-75 °C, 50%-100 °C, 60%-75 °C, and 60%-100 °C) were produced at pilot scale, from emulsions with 50 or 60% TS pasteurized at 75 or 100 °C for 18 s. Both the emulsion feeds and the emulsions from the reconstituted powders (12.5% TS) were analyzed. The results showed that feeds with 60% TS were flocculated, as indicated by the large particle size and viscosity and the pseudoplastic behavior. Light microscopy revealed that, during spray drying, the flocs were disrupted in 60%-100 °C, while the 60%-75 °C emulsion remained flocculated, reducing its stability post-reconstitution. Although all four emulsions were mainly stabilized by caseins, the presence of β-lactoglobulin was also detected at the oil-water interface, in native state in the formulas preheated at 75 °C and aggregated in the formulas preheated at 100 °C. In conclusion, both the degree of whey protein denaturation (resulting from pasteurization) and the TS of the concentrates during infant formula production affected the emulsion stability of the reconstituted powders.

Formulation of the Polysaccharide FucoPol into Novel Emulsified Creams with Improved Physicochemical Properties

Driven by the customers' growing awareness of environmental issues, the production of topical formulations based on sustainable ingredients is receiving widespread attention from researchers and the industry. Although numerous sustainable ingredients (natural, organic, or green chemistry-derived compounds) have been investigated, there is a lack of comparative studies between conventional ingredients and sustainable alternatives. In this study, olive oil (30 wt.%) and α-tocopherol (2.5 wt.%) containing oil-in-water (O/W) emulsions stabilized with the bacterial fucose-rich polysaccharide FucoPol were formulated envisaging their validation as cosmetic creams. After formula composition design by Response Surface Methodology (RSM), the optimized FucoPol-based emulsion was prepared with 1.5 wt.% FucoPol, 1.5 wt.% cetyl alcohol, and 3.0 wt.% glycerin. The resulting emulsions had an apparent viscosity of 8.72 Pa.s (measured at a shear rate 2.3 s^-1) and droplet size and zeta potential values of 6.12 µm and -97.9 mV, respectively, which are within the values reported for cosmetic emulsified formulations. The optimized formulation displayed the desired criterium of a thin emulsion system, possessing the physicochemical properties and the stability comparable to those of commercially available products used in cosmeceutical applications.

Thoroughly review the recent progresses in improving O/W interfacial properties of proteins through various strategies

Along with the future food market developing world widely, the personalized nutrition and rational function food design are found to be urgently attracted. Oil in a water (O/W) emulsion system has an excellent ability to maintain nutraceuticals and thus plays a promising role in producing future functional foods. Understanding the interfacial related mechanisms involved are essential for improving the quality of food products. Protein can effectively reduce interfacial tension and stable immiscible phases. The interfacial properties of proteins directly affect the emulsion qualities, which have gradually become a prospective topic. This review will first briefly discuss the interfacial-related fundamental factors of proteins. Next, the paper thoroughly overviewed current physical and chemical strategies tailored to improving the interfacial and emulsion properties of proteins. To be summarized, a higher flexibility could allow protein to be more easily unfolded and adsorbed onto the interface but could also possibly form a softer interfacial film. Several physical strategies, such as thermal, ultrasound and especially high-pressure homogenization are well applied to improve the interfacial properties. The interfacial behavior is also altered by various green chemical strategies, such as pH adjustment, covalent modification, and low molecular weight (LMW) surfactant addition. These strategies upgraded emulsion properties by increasing adsorption load, accelerating diffusion and adsorption rate, associated with lowering interfacial tension, and promoting interfacial protein interactions. Future researches targeted at elucidating interfacial-bulk protein interactions, unraveling interfacial behavior through in silico tools, exploring connection between interfacial-industrial processing properties, and clarifying the interfacial-sensory-digestive relationships of O/W emulsions is needed to develop emulsion applications.

Study on stability of grape seed oil/rice hydrolyzed protein emulsion

In this study, the stability mechanism of grape seed oil/rice hydrolyzed protein emulsion was studied. The grape seed oil (10% v/v) and rice hydrolyzed protein (2% w/v) were homogenized under high pressure to prepare the emulsion. It was observed by CLSM and Multiple light scatterometer that the emulsion had long-term storage stability, and the average particle size of droplets was 0.984–1.363 µm. ζ-potential ranged from −37.733 mV to −25.633 mV. It is found that the emulsion has strong resistance to temperature, ions and other environmental factors from the macroscopic and microscopic structure, and no emulsion stratification phenomenon occurs. The composite emulsion can be used in the field of food industry and fine chemical industry, which can provide nutrition and functionality of products, its research has certain value and has a wide space for development.

Characterization and stability of peppermint oil emulsions using polyglycerol esters of fatty acids and milk proteins as emulsifiers

Three peppermint oil emulsions using polyglycerol esters of fatty acids-casein (PGFE-CN), polyglycerol esters of fatty acids-sodium caseinate (PGFE-NaCN), and polyglycerol esters of fatty acids-whey protein isolate (PGFE-WPI) as emulsifiers were fabricated, and the droplet size, zeta potential, viscosity, and stability of emulsions were determined. The experimental results showed that the emulsion containing PGFE-CN has relatively smaller droplet size of 231.77 ± 0.49 nm. No significant changes were observed on the average particle size, polydispersity index and zeta potential during 4-week of storage, indicating that the emulsions kept stable against pH, salt ion, freeze-thaw, and storage. Fourier transform infrared spectrometer (FTIR) results showed that the electrostatic interaction occurs between CN and PGFE in the emulsion. The confocal laser scanning microscope (CLSM) was used to observe the microstructure of the emulsion, proving that droplets were evenly distributed throughout the aqueous phase by PGFE-CN emulsifier. The protein-stabilized emulsions can be used as potential carriers for the delivery of the lipophilic nutrients such as peppermint oil. PRACTICAL APPLICATION: PGFE-CN emulsifier can be directly added to the beverage systems containing oil or protein, such as coconut milk, peanut milk, and walnut milk. It can enhance the stability of beverage, prevent the precipitation, stratification, and oil floating, improve the homogeneity of the system and therefore extend the shelf life.

Comparative Study of Physicochemical Properties of Nanoemulsions Fabricated with Natural and Synthetic Surfactants

This work aims to evaluate the effect of two natural (whey protein isolate, WPI, and soy lecithin) and a synthetic (Tween 20) emulsifier on physicochemical properties and physical stability of food grade nanoemulsions. Emulsions stabilized by these three surfactants and different sunflower oil contents (30% and 50% w/w), as the dispersed phase, were fabricated at two levels of homogenization pressure (500 and 1000 bar). Nanoemulsions were characterized for droplet size distribution, Zeta-potential, rheological properties, and physical stability. Dynamic light scattering showed that droplet size distributions and D50 values were strongly affected by the surfactant used and the oil content. WPI gave similar droplet diameters to Tween 20 and soy lecithin gave the larger diameters. The rheology of emulsions presented a Newtonian behavior, except for WPI-stabilized emulsions at 50% of oil, presenting a shear-thinning behavior. The physical stability of the emulsions depended on the surfactant used, with increasing order of stability as follows: soy lecithin < Tween 20 < WPI. From our results, we conclude that WPI is an effective natural replacement of synthetic surfactant (Tween 20) for the fabrication of food-grade nanoemulsions.

A Multiscale Approach to the Design and Manipulation of Oil-in-Water Emulsion-Based Products

Advances in computational technology and high-throughput modeling software have given rise to the tailored design of products that require accurate mathematical relationships for their assessment. Industrial emulsion-based products, ubiquitous to everyday life, are complex systems driven by interfacial phenomena that require quick property-prediction tools for their commercialization. In this work, by means of a multiscale approach, mathematical relationships to model oil-in-water emulsions and that can be applied to any commercial emulsion-based product are proposed. The energy consumption during the emulsification process ( $E_v$ , which transitions from monotonic increase to exponential growth at 80%  $w/w$ ), a parameter responsible for finished product performance, was linked to final product properties at three different levels: (i) molecular, through the dynamics of the interdroplet interactions given their distribution and structure at a microscopic level; (ii) microscopic, through average droplet size yielding an inversely proportional exponential relationship ( $D_{\left[\mathrm{4,3}\right]}\propto E_v^{-4}$ ); and (iii) macroscopic, through the plateau value of the elastic modulus and the flow behavior index leading to inversely proportional quadratic relationships ( $G^{\prime }\propto E_v^{-2}$ and $\eta \propto E_v^{-2}$ , respectively). These relationships are valid at dispersed phase concentrations beyond the 60%  $w/w$ threshold where the packing of the droplets changes the emulsion’s microscopic structure giving rise to Van der Waals forces-driven phenomena. Finding this threshold allowed expanding the concentration ranges of previously reported models. The main expectation is that these results will aid researchers and process/product designers to optimize their work in different industrial applications.

Rheological and Antimicrobial Properties of Chitosan and Quinoa Protein Filmogenic Suspensions with Thyme and Rosemary Essential Oils

Food packaging faces the negative impact of synthetic materials on the environment, and edible coatings offer one alternative from filmogenic suspensions (FS). In this work, an active edible FS based on chitosan (C) and quinoa protein (QP) cross-linked with transglutaminase was produced. Thyme (T) and rosemary (R) essential oils (EOs) were incorporated as antimicrobial agents. Particle size, Z potential, and rheological parameters were evaluated. The antimicrobial activity against Micrococcus luteus (NCIB 8166) and Salmonella sp. (Lignieres 1900) was monitored using atomic force microscopy and image analysis. Results indicate that EOs incorporation into C:QP suspensions did not affect the Z potential, ranging from -46.69 ± 3.19 mV to -46.21 ± 3.83 mV. However, the polydispersity index increased from 0.51 ± 0.07 to 0.80 ± 0.04 in suspensions with EO. The minimum inhibitory concentration of active suspensions against Salmonella sp. was 0.5% (v/v) for thyme and 1% (v/v) for rosemary. Entropy and fractal dimension of the images were used to confirm the antimicrobial effect of EOs, which modified the surface roughness.

Biomimetic water-in-oil water/pMDI emulsion as an excellent ecofriendly adhesive for bonding wood-based composites

In this study, a novel and environmental strategy inspired by mussels is reported for the construction of a high-performance water-in-oil water/pMDI adhesive with strongly adherent catechol groups. It is found that the design of the biomimetic water-in-oil emulsion significantly increases the apparent viscosity and storage stability of the adhesive, which in turn influences the handling and bonding performance in practical application. Additionally, although the biomimetic emulsion design consumes part of active isocyanate groups in the pMDI, the contained catechol can serve as a reactive platform to induce secondary crosslinking interactions with the wood substrate to further improve the mechanical and adhesion performances of the modified pMDI adhesives. Consequently, compared to the pristine pMDI sample, the wet shear strength of the biomimetic water-in-oil water/pMDI adhesive is increased by 129.7 %, exhibiting that the obvious optimization of adhesion and water resistance properties. Overall, our findings provide new insights into exploiting novel and superior wood adhesives, and the constructed high-performance adhesive presents potential applications for sustainable wood products.