Emulsion stability and dilatational rheological properties of soy/whey protein isolate complexes at the oil-water interface: Influence of pH

Constructing myosin/high-density lipoprotein composite emulsions: Roles of pH on emulsification stability, rheological and structural properties

The emulsification activity of myosin plays a significant role in affecting quality of emulsified meat products. High-density lipoprotein (HDL) possesses strong emulsification activity and stability due to its structural characteristics, suggesting potential for its utilization in developing functional emulsified meat products. In order to explore the effect of HDL addition on emulsification stability, rheological properties and structural features of myosin (MS) emulsions, HDL-MS emulsion was prepared by mixing soybean oil with isolated HDL and MS, with pH adjustments ranging from 3.0 to 11.0. The results found that emulsification activity and stability in two emulsion groups consistently improved as pH increased. Under identical pH, HDL-MS emulsion exhibited superior emulsification behavior as compared to MS emulsion. The HDL-MS emulsion under pH of 7.0-11.0 formed a viscoelastic protein layer at the interface, adsorbing more proteins and retarding oil droplet diffusion, leading to enhanced oxidative stability, compared to the MS emulsion. Raman spectroscopy analysis showed more flexible conformational changes in the HDL-MS emulsion. Microstructural observations corroborated these findings, showing a more uniform distribution of droplet sizes in the HDL-MS emulsion with smaller particle sizes. Overall, these determinations suggested that the addition of HDL enhanced the emulsification behavior of MS emulsions, and the composite emulsions demonstrated heightened responsiveness under alkaline conditions. This establishes a theoretical basis for the practical utilization of HDL in emulsified meat products.

Influence of carboxymethyl cellulose on the stability, rheology, and curcumin bioaccessibility of high internal phase Pickering emulsions

Recently, there has been a focus on using biopolymer-based particles to stabilize high internal phase Pickering emulsions (HIPPEs) due to the notable advances in biocompatibility and biodegradability. In this work, the complex particles of peanut protein isolate and carboxymethyl cellulose (CMC) with various substitution degrees (DS; 0.7 and 0.9) and weight average molecular weights (Mw; 90, 250, and 700 kDa) were prepared and characterized as novel stabilizers. For the obtained four types of morphologically distinct particles, the complex particles formed by CMC (0.9 DS and 250 kDa) showed cluster structures with an average size of 1.271 μm, equally biphasic wettability with three-phase contact angles of 91.5°, and the highest diffusion rate at the oil-water interface. HIPPEs stabilized by these particles exhibited more elastic behavior due to the smaller tanδ and higher viscosity, as well as excellent thixotropic recovery properties and stability against heating, storage, and freeze-thawing. Furthermore, confocal laser scanning microscopy verified that these particles formed a dense interfacial layer around the oil droplets, which could resist flocculation and coalescence between oil droplets during in vitro digestion. The improved bioaccessibility of curcumin-loaded HIPPEs made these delivery systems potentially apply in functional foods.

Curdlan-polyphenol complexes prepared by pH-driven effectively enhanced their physicochemical stability, antioxidant and prebiotic activities

In this study, the curdlan-polyphenol complexes were constructed by a pH-driven method. The interaction between curdlan and various hydrophobic polyphenols (curcumin, quercetin, and chlorogenic acid) was investigated. Curdlan could self-assemble into particles for loading polyphenols through hydrogen bonding and hydrophobic interactions. The three polyphenols were embedded in curdlan in an amorphous state. The curdlan-curcumin complex showed the lowest viscoelasticity but exhibited the highest curcumin loading ability (34.04 ± 1.73 mg/g). However, the curdlan-chlorogenic acid complex emerged the opposite trend, indicating that the loading capacity was associated with the hydrophobicity of polyphenols. The antioxidant activity of curdlan significantly increased after combining with polyphenols, which could be maintained during in vitro simulated gastrointestinal digestion. In particular, the curdlan-quercetin complex exhibited the highest antioxidant activity and short-chain fatty acid concentration, which could influence gut microbiota composition by promoting the proliferation of Prevotella and inhibiting the growth of Escherichia_Shigella. In conclusion, the curdlan-polyphenol complexes prepared by an alcohol-free pH-driven method could effectively enhance the gastrointestinal stability of polyphenols as well as increase the antioxidant and prebiotic activities of curdlan, which could be applied as a functional ingredient to improve gut health.

Alcalase-hydrolyzed insoluble soybean meal hydrolysate aggregates: Structure, bioactivity, function properties, and influences on the stability of oil-in-water emulsions

We studied the influences of hydrolysis time on the structure, functional properties, and emulsion stability of insoluble soybean meal hydrolysate aggregates (ISMHAs). We assume that the ISMHAs produced by soybean meal can be used as emulsifiers to prepare stable emulsions. The molecular weights of these ISMHAs were below 53 kDa. After hydrolysis, a decrease in α-helices and an increase in random coils indicated that the soybean meal proteins were unfolding. Moreover, the fluorescence intensity, UV absorption, and surface hydrophobicity of ISMHAs increased. These results would contribute to their antioxidant activity and functional properties. Additionally, the 90-min ISMHA sample exhibited the highest ABTS+• scavenging activity (80.02 ± 4.55 %), foaming stability (52.92 ± 8.06 %), and emulsifying properties (emulsifying activity index of 97.09 m2/g; emulsifying stability index of 371.47 min). The 90-min ISMHA emulsion exhibited the smallest particle size and excellent storage stability. Soybean meal peptide by-product emulsifier has potential for sustainable application.

Dandelion polysaccharides improve the emulsifying properties and antioxidant capacities of emulsions stabilized by whey protein isolate

In this study, the effects of dandelion polysaccharide (DP) and its carboxymethylated derivative (CMDP) on the emulsifying characteristics and antioxidant capacities of emulsions stabilized by whey protein isolate (WPI) were determined. The addition of both DP and CMDP reduced the particle size and zeta potential of the emulsions. Using 1.0 % WPI and 1.0 % CMDP as emulsifier, the emulsifying activity index (EAI) and emulsifying stability index (ESI) were 32.61 ± 0.11 m2/g and 42.58 ± 0.13 min, respectively, which were higher than the corresponding values of 27.19 ± 0.18 m2/g and 36.17 ± 0.15 min with 1.0 % WPI and 1.0 % DP. Fourier-transform infrared spectroscopy (FT-IR), far-ultraviolet circular dichroism (Far-UV CD), and fluorescence (FS) spectra analyses confirmed that the α-helix and β-sheet structures in WPI-polysaccharide complexes were reduced compared with those in pure WPI, whereas the random-coil content was enhanced by the addition of polysaccharides. Moreover, DP and CMDP effectively improved the antioxidant capacity and inhibited oxidation of the emulsions during storage. Therefore, DP and its carboxymethylated derivative exhibit great potential to be applied in the emulsion-based delivery system.

Stability and Bioaccessibility of Quercetin-Enriched Pickering Emulsion Gels Stabilized by Cellulose Nanocrystals Extracted from Rice Bran

To investigate the optimal delivery system of quercetin, in this paper, cellulose nanocrystals (CNCs) extracted from rice bran were used to stabilize the Pickering emulsion and Pickering emulsion gels (PEGs) with quercetin. To compare the emulsion properties, stability, antioxidation activity, encapsulation rate, and bioaccessibility of the quercetin, four emulsions of CNC Pickering emulsion (C), CNC Pickering emulsion with quercetin (CQ), CNC Pickering gel emulsion (CG), and CNC Pickering gel emulsions with quercetin (CQG) were prepared. All four emulsions exhibited elastic gel network structure and good stability. The quercetin significantly reduced the particle size, increased the stability, and improved the antioxidant capacity of CQ and CQG. Compared to C and CG, the ABTS+ radical scavenging capacities of CQ and CQG were respectively enhanced by 46.92% and 3.59%. In addition, CQG had a higher encapsulation rate at 94.57% and higher bioaccessibility (16.17) compared to CQ. This study not only indicated that CNC from rice bran could be exploited as an excellent stabilization particle for Pickering emulsions, but also provided a highly stable and bioaccessible delivery system for water-insoluble functional active factors.

Effect of NaCl concentration on the formation of high internal phase emulsion based on whey protein isolate microgel particles

At present, the effect of structural modification of microgel particles on high internal phase emulsions (HIPEs) is less studied. In this study, the structural modification effect of NaCl on whey protein isolate microgels (WPIMPs) was comprehensively characterized and applied to the construction of HIPEs. WPIMPs were prepared with NaCl (0-150 mM) and the structural changes were analyzed by measuring the particle size, Zeta-potential, and endogenous fluorescence spectra. The results showed that inducing WPIMPs by NaCl enhanced the surface hydrophobicity, decreased the Zeta potential, and elevated the degree of cross-linking. The interfacial behavior of WPIMPs was characterized by measuring interfacial tensions and adsorbed layer properties. The results showed that NaCl induction decreased the interfacial tension, increased the thickness of the adsorbed layer, and improved the viscoelasticity. The HIPEs were analyzed for micromorphology and particle sizes. The results indicated that NaCl-induced WPIMPs favored the formation of HIPEs with small particle sizes and provided HIPEs with superior environmental stability. This study provides a new idea for the structural modification of microgels and a new theoretical basis for the construction conditions of HIPE.

Regulation of interfacial mechanics of soy protein via co-extraction with flaxseed protein for efficient fabrication of foams and emulsions

Enrichment of plant proteins with functionality is of great importance for expanding their application in food formulations. This study proposed an innovation to co-enrich soy protein and flaxseed protein to act as efficient interfacial stabilizers for generating foams and emulsions. The structure, interfacial properties, and functionalities of the soy protein-flaxseed protein natural nanoparticles (SFNPs) obtained by alkali extraction-isoelectric precipitation (AE) and salt extraction-dialysis (SE) methods were investigated. Overall, the foamability of AE-SFNPs (194.67 %) was 1.45-fold that of SE-SFNPs, due to their more flexible structure, smaller particle size, and suitable surface wettability, promoting diffusion and adsorption at the air-water interface. AE-SFNPs showed higher emulsion stability (140.89 min), probably because the adsorbed AE-SFNPs with smaller size displayed soft particle-like properties and stronger interfacial flexibility, and therefore could densely and evenly arrange at the interface, facilitating the formation of a stiff and solid-like interfacial layer, beneficial for more stable emulsion formation. The findings may innovatively expand the applications of SFNPs as food ingredients.

Emulsifying properties of O/W emulsion stabilized by soy protein isolate and γ-polyglutamic acid electrostatic complex

In order to improve the emulsifying properties of soy protein around isoelectric point, soy protein isolate (SPI) and γ-polyglutamic acid (γ-PGA) complexes were prepared by electrostatic interaction. The formation of SPI-γ-PGA electrostatic complex and emulsifying properties were investigated by monitoring turbidity, zeta potential, intrinsic fluorophores, emulsion characterization, and microstructure observation. The results showed that the formation of SPI-γ-PGA electrostatic complex was identified through turbidimetric analysis and zeta-potential measurement. Intrinsic fluorescence spectrum indicated internal structure changes of electrostatic complexes. Furthermore, SPI-γ-PGA complex-stabilized emulsions showed better stability with small droplet sizes and slow growth as well as the uniform microstructure around the isoelectric point (pH 4.0-5.0) than SPI-formed emulsions. Under the different thermal treatments and ionic strengths, emulsions stabilized by SPI-γ-PGA-soluble complex resulted in improved emulsion stability to environmental stresses. This may be attributed to the increased steric repulsion and electrostatic repulsion by SPI-γ-PGA complexes at oil-water interfaces. The findings derived from this research would provide theoretical reference about SPI-γ-PGA electrostatic complex that can be applied in acid beverages and developed a novel plant-based sustainable stabilizer for emulsions. PRACTICAL APPLICATION: The electrostatic interaction between SPI and γ-PGA improved the emulsifying characteristics of soy protein around isoelectric point. The results derived from this research would expand applications of SPI-γ-PGA-soluble electrostatic complex that can be applied in acid beverages, as well as a novel plant-based sustainable stabilizer for emulsions.

Investigating the effect of wall material and pressure homogenisation on encapsulation parameters and thermal stability in chia seed oil microcapsules

AIM

To evaluate the effect of different wall material (WM) matrices followed by homogenisation to encapsulate chia seed oil (CSO) using freeze drying technology.

METHODS

CSO was encapsulated using three ratios (100/0, 50/50, and 100/0) of two WM matrices: MTS/WPC (modified tapioca starch-whey protein concentrate) and MD/WPC (maltodextrin-whey protein concentrate). The evaluation included encapsulation efficiency (EE), oxidative stability, and α-linolenic acid (ALA) retention. Homogenised microcapsules (-H) were then assessed for storage and thermal stability, along with cumulative oil release.

RESULTS

The MD-WPC-H 50/50 microcapsules had superior EE (97.32%), higher ALA retention (60.2%), storage stability (up to 30 days), higher thermal stability (up to 700 °C), and desirable oil release in simulated condition.

CONCLUSION

Selecting suitable WM and homogenisation is key for improving EE, storage, thermal stability, and targeted release. The CSO microcapsule can serve as a functional ingredient to improve the quality of diverse food products.

pH-induced physiochemical and structural changes of milk proteins mixtures and its effect on foaming behavior

Milk proteins are well known to produce aerated food due to the amphiphilicity. However, milk proteins are commonly added in blends for the desirable properties in food industry. In this study, the foaming properties of milk protein mixtures (MPM), a mixtures of whey protein isolated (WPI) and milk protein concentrate (MPC), was studied through foaming capacity (FC), foam stability (FS), and foam morphology at pH 3.0-9.0. Physiochemical, structural, surface properties, and Pearson correlation analysis were measured to gain insight into foaming behavior. Results indicated that MPM showed excellent FC (113.0-114.3 %) and FS (90.7-93.0 %) at pH 6.0-9.0, and foam displayed a smaller size and uniform distribution. MPM solutions showed smaller particles, higher solubility, and lower apparent viscosity at pH 6.0-9.0, which resulted in an increase in surface pressure and adsorption rate (Kdiff), facilitating more protein absorbed to interface. To further investigate structural changes, various spectral methods were used, in which the structure of MPM was changed with pH. Correlation analysis further suggests that Kdiff and solubility positively affect the formation of foam, while free sulfhydryl and β-sheet contributed to stabilizing foams. These findings provide valuable information on MPM as ingredients for aerated foods under acidic, neutral, and alkaline conditions.

Effects of limited enzymatic hydrolysis and polysaccharide addition on the physicochemical properties of emulsions stabilized with duck myofibrillar protein under low-salt conditions

This study aimed to investigate the role of hydrolysis and guar gum (GG) participation on the emulsification of the duck myofibrillar protein (MP) and the related stability of oil-in-water emulsion in low-salt condition. Emulsions were prepared using one of each or both treatments, and that prepared with trypsin hydrolysis and GG (T-GG) exhibited the highest stability. FTIR analysis confirmed the hydrogen bond interactions between the system components. T-GG treatment improved emulsion properties and decreased oil droplet size. Moreover, CLSM indicated that aggregation of T-GG oil droplets was prevented. Physical stability was assessed such as Turbiscan stability index, creaming index, and rheological properties. The adsorbed percentage for T-GG was the lowest. However, interfacial tension, droplet size, stability, and peroxide value analyses indicated that a denser interfacial membrane structure is formed with T-GG. Thus, T-GG treatment could be applied in the food industry, such as in nutrient delivery systems and fat mimetics.

Rotor-Stator Emulsification in the Turbulent Inertial Regime: Experiments toward a Robust Correlation for the Droplet Size

The Sauter mean diameter, d32, is a representative parameter in emulsions that indicates the average size of the oil droplets once the emulsion becomes stable. Several mathematical and physical approaches have been employed in the literature to seek expressions for d32 under different conditions. The present work sheds light on this rich literature and emphasizes that the characterization of emulsions is still a fertile field for investigation. In this paper, a new Π-theorem-based model to predict the normalized Sauter mean diameter for the specific case of rotor-stator emulsification is sought by applying a multiple regression analysis on experimental data of oil-in-water (O-W) emulsions produced using three different oils: paraffin, soybean oil, and isopropyl myristate, at different oil-to-water (O/W) ratios and rotor speeds. The proposed model quantifies the roles of the viscous, inertial, and interfacial tension forces, besides the O/W ratio, in the emulsification process within the turbulent inertial subrange. The developed empirical correlation is then contrasted with relevant literature models for reliability assessment; predictions of the present explicit model are proven to be more accurate for the fluid properties and the experimental conditions under study.

Assessing the emulsifying properties of Tenebrio molitor larvae protein preparations: Impact of storage, thermal, and freeze-thaw treatments on o/w emulsion stability

Insect proteins have gained attention as novel ingredients, which may contribute to the development of high-value-added products. This study evaluates the emulsifying and emulsion-stabilizing properties of Tenebrio molitor larvae protein preparations obtained through different procedures, leading to the following rich-in-protein samples: ASP (∼67 %), AIP (∼75 %), and SSP (∼62 %). The method applied for protein isolation influenced the molecular and structural characteristics of the preparations, thus affecting their adsorption behaviour at oil-water interfaces and ability to stabilize emulsions. O/w emulsions were prepared, and their physicochemical stability was assessed with respect to droplet size, oil droplet flocculation/coalescence, microstructure, and creaming upon storage as well as after thermal and freeze-thaw treatments. The use of ASP and AIP protein preparation as emulsifiers led to higher stability during storage. All emulsions were stable upon heating and able to withstand two freeze-thaw cycles without phase separation, although there was an increase in droplet size. Interestingly, the AIP emulsion remained stable after the 3rd freeze-thaw cycle, indicating remarkable stability under freezing compared to the other two emulsions. These findings are of great importance for the formulation of food-grade emulsions using insect protein preparations and their future exploitation in developing food items subjected to different treatments.

Elevating meat products: Unleashing novel gel techniques for enhancing lipid profiles

Rising health concerns and the diet-health link drive demand for healthier foods, prompting meat manufacturers to reformulate traditional products. These manufacturers have reduced fat content to enhance nutritional quality, which is essential for maintaining desired product features. As a result, numerous strategies have emerged over recent decades to decrease fat and enhance the lipid profiles of meat products. Among these strategies, using hydrocolloids, emulsification, encapsulation, or gelation of oils to produce fat substitutes stands out. Using gels allows fat replacers with characteristics similar to animal fat (similar rheological, physical, or appearance properties) but with a much healthier lipid profile (by incorporating highly unsaturated oils). Therefore, this manuscript aims to comprehensively describe the main fat replacers used to prepare meat products. In addition, an in-depth review of the latest studies (2022-2023) that use novel gels to reform meat products has been made, indicating in each case the implications that the reformulation produces at a physicochemical, nutritional, and sensory level. Given the reported results, it seems clear that the strategy of using bigels or emulgels is very promising and allows obtaining nutritionally highly improved meat products without affecting their sensory or physicochemical properties. However, the best conditions to obtain a novel gel suitable for use as a fat substitute for each meat product still need to be studied and correctly defined. Moreover, these advancements can pave the way for more extensive studies on using novel gel techniques in other food industries, expanding their applicability and leading to healthier consumer options across various food categories.

Functionalization of pine kernel protein by pH-shifting combined with ultrasound treatments: Further improvement with increasing acidity

As a novel plant protein, developing various aspects of pine kernel protein (PKP) functionality is essential to meet the demand for protein-rich foods. To achieve this, the PKP was functionalized by a combination of pH-shifting and ultrasound techniques. The solubility, emulsification and droplet stability of the PKP in the pH range suitable to food (pH 3 to 7) were further investigated. The pH 12-shifting was an effective strategy to increase the solubility of PKP under extreme acidic and neutral conditions, characterized by a higher content of β-sheets and random coils, a greater exposure of free sulfhydryl and hydrophobic groups. Furthermore, appropriate ultrasonic power (250 W) further improved the solubility of PKPs by disrupting intermolecular hydrogen and hydrophobic bonds. As the ambient acidity increased, the emulsions exhibited higher viscoelasticity and stronger protein interactions. Especially at pH 3, the oil droplets stabilized by U250-PKP-12 (PKP treated with 250 W ultrasound-assisted pH 12-shifting) were homogeneously dispersed and surrounded by dense protein, maintaining small particle size and large electrostatic repulsion, and there was no apparent creaming or phase separation in the emulsions after 10 days of storage. Thus, the functionality of PKP after pH-shifting combined with ultrasonic treatments is further enhanced by increasing the environmental acidity.

Stability and Digestive Properties of a Dual-Protein Emulsion System Based on Soy Protein Isolate and Whey Protein Isolate

The stability and digestive properties of a dual-protein emulsion consisting of soy protein isolate (SPI) and whey protein isolate (WPI) have been systematically studied. The results showed that the particle size and viscosity of the dual-protein emulsion system decreased continuously with the increase in WPI, and this might be related to the large amount of electric charge on the surface of the emulsion droplets. Dual-protein emulsions with ratios of 3:7 and 5:5 showed the highest emulsion activity, while emulsion stability increased with the increase in WPI. The thicker adsorption layer formed at the interface might have contributed to this phenomenon. After in-vitro-simulated digestion, the emulsion droplet particle size increased substantially due to the weakened electrostatic repulsion on the droplet surface, especially for the intestinal digestion phase. Meanwhile, WPI accelerated the release of free fatty acids in the digestion process, which played a positive role in the nutritional value of the dual-protein emulsion. In accelerated oxidation experiments, WPI also improved the antioxidant properties of the dual-protein emulsion system. This study will provide a new insight and necessary theoretical basis for the preparation of dual-protein emulsions.

Sodium alginate emulsion loaded with linalool: Preparation, characterization and antibacterial mechanism against Shigella sonnei

This study aimed to prepare sodium alginate-linalool emulsion (SA-LE) to overcome the low solubility of linalool and explore its inhibitory activity against Shigella sonnei. The results indicated that linalool significantly reduced the interfacial tension between SA and oil phase (p < 0.05). Droplet sizes of fresh emulsions were uniform with sizes from 2.54 to 2.58 μm. The ζ-potential was between -23.94 and -25.03 mV, and the viscosity distribution was 973.62 to 981.03 mPa·s at pH 5-8 (near neutral pH) without significant difference. In addition, linalool could be effectively released from SA-LE in accordance with the Peppas-Sahlin model, mainly described by Fickian diffusion. In particular, SA-LE can inhibit S. sonnei with a minimum inhibitory concentration of 3 mL/L, which was lower than free linalool. The mechanism can be described as damaging the membrane structure and inhibiting respiratory metabolism accompanied by oxidative stress based on FESEM, SDH activity, ATP and ROS content. These results suggest that SA is an effective encapsulation strategy to enhance the stability of linalool and its inhibitory effect on S. sonnei at near neutral pH. Moreover, the prepared SA-LE has the potential to be developed as a natural antibacterial agent to address the growing food safety challenges.

Improving the biological activity, functional properties, and emulsion stability of soybean meal hydrolysate via covalent conjugation with polyphenol

The use of by-products as functional components in food production is gaining popularity. This study investigated the structure, biological activity, interaction force, and emulsion stability of soybean meal hydrolysate (SMHs) after covalent conjugation with proanthocyanidin (PC), epigallocatechin (EGCG), gallic acid (GA), and caffeic acid (CA). SDS-PAGE confirmed the formation of SMHs-polyphenol conjugates. Structural analysis indicates unfolding and disordered-structure formation. This transformation directly influenced the antioxidant activity and emulsification of SMHs. The antioxidant and emulsifying properties of all covalent complexes were superior to SMHs, in order of SMHs-PC, SMHs-EGCG, SMHs-GA, and SMHs-CA. Among, SMHs-PC conjugates displayed the highest antioxidant activity (ABTS^•+ and DPPH radical scavenging capacities of 89.33% and 52.71%, respectively), total polyphenol content (235.10 mg/g), and emulsification activity (EAI) and stability (ESI) values (109.27 m²/g and 135.05 min, respectively). Moreover, SMHs-PC emulsion showed the smallest particle size (467.20 nm), highest viscosity (520.19 Pa.s), highest protein adsorption (94.33%), and lowest release rate of free fatty acids (FFAs) (18.61%) after digestion. These results provided valuable information for the use of modified SMHs as emulsifiers, which is a promising approach for increasing the value of soybean meal.

Characterization of bacterial cellulose nanofibers/soy protein isolate complex particles for Pickering emulsion gels: The effect of protein structure changes induced by pH

In this work, the influence of soy protein isolated at different pH values (1-9) on the self-assembly behaviors of bacterial cellulose nanofibers/soy protein isolate (BCNs/SPI) colloidal particles via anti-solvent precipitation were investigated. The results showed that the formation of BCNs/SPI at pH values of 1-5 was mainly driven by electrostatic interaction, while the formation of those at pH values of 5-9 was driven by weak molecular interactions including hydrogen bonding and steric-hindrance effect. The FTIR demonstrated that the conformation of protein involved a transition from order to disorder at the level of secondary structure as pH values were away from the isoelectric point. The fluorescence spectroscopy and UV-vis adsorption spectroscopy indicated that hydrophobic region of SPI at pH value of 5 displayed more exposed as compared with that at pH values away from the isoelectric point. The changes in structure conformation of SPI induced by pH values led to the changes in properties of the BCNs/SPI colloidal particles including particle size, microstructure, crystallinity, hydrophily, thermal stability, and rheological properties. Furthermore, the structures of BCNs/SPI colloidal particles at different pH values significantly affected the stability of Pickering emulsion gels stabilized by the corresponding complex colloidal particles. This study provided a theoretical basis for the design of food-grade Pickering emulsion gels stabilized by BCNs/SPI complex colloidal particles.

Static stability of partially crystalline emulsions: Impacts of carrageenan and its blends with xanthan gum and/or guar gum

In the present study, four different combinations of gums, including carrageenan (CG), its binary blends with xanthan gum (XG) or guar gum (GG) in equal ratios, and its ternary blends with XG and GG in three equal ratios, were involved into making partially crystalline emulsions (PCEs), respectively. The freshly prepared emulsions were systematically characterized by rheological property, particle size distribution, microscopic morphology, interfacial property, and intermolecular interactions, and their emulsion stabilities were further evaluated using multiple light scattering technique and storage test. All PCEs stabilized by gum blends (CG + XG, CG + GG, and CG + XG + GG) obtained decreased apparent viscosities at 0.01 s^-1 (10.12-25.32 Pa·s), particle sizes (3.12-4.06 μm), as well as interfacial protein concentrations (22.60-27.01 mg/m²), which were much lower than those with single CG (35.98 Pa·s, 6.72 μm, and 47.74 mg/m², respectively). The microscopic morphology showed that blending CG with XG and/or GG contributed to formation of firmer three-dimensional matrix, thereby preventing the aggregation of fat droplets. Inclusion of XG and/or GG also significantly reduced contribution of hydrophobic interactions from 0.72 to 0.24-0.44 mg/mL. Both multiple light scattering and storage test revealed that emulsion instabilities were mainly manifested as a clarification at the bottom and an agglomeration at the top. PCE-CG + XG + GG exhibited superior stability with low creaming index (6.20 %) and viscosity (1180.0 mPa·s) after three months of storage. The research aims to evaluate the effects of CG and its blends with XG and GG on stability of PCEs, and the results potentially provide valuable information for manufacture of stable PCE foods.

Emulsion Properties during Microencapsulation of Cannabis Oil Based on Protein and Sucrose Esters as Emulsifiers: Stability and Rheological Behavior

The effects of different emulsifiers, such as soy protein isolate-sucrose ester (SPI-SE) and whey protein isolate-sucrose ester (WPI-SE), on the properties of the emulsion during the microencapsulation of cannabis oil were studied. The influence of SE concentration on the emulsion properties of the two emulsifying systems was analyzed. The results of the adsorption kinetics show that SE can decrease the interfacial tension, particle size and zeta potential of the emulsions. The results of the interfacial protein concentration show that SE could competitively replace the protein at the oil-water interface and change the strength of the interfacial film. The results of the viscoelastic properties show that the emulsion structure of the two emulsion systems results in the maximum value when the concentration of SE is 0.75% (w/v), and the elastic modulus (G') of the emulsion prepared with SPI-SE is high. The viscosity results show that all emulsions show shear-thinning behavior and the curve fits well with the Ostwald-Dewaele model. The addition of SE in the emulsions of the two emulsion systems can effectively stabilize the emulsion and change the composition and strength of the oil-water interface of the emulsion. The cannabis oil microcapsules prepared with protein-SE as an emulsion system exhibit high quality.

Fabrication of Antioxidant Pickering Emulsion Based on Resveratrol-Grafted Zein Conjugates: Enhancing the Physical and Oxidative Stability

Lipid oxidation is still a major problem complicating the development of food emulsions. In this study, an antioxidant Pickering emulsion stabilized by resveratrol-grafted zein (Z-R) conjugates and pectin (P) complex particles was prepared. The hydrophilic pectin successfully adjusted the wettability of Z-R; when the mass ratio of Z-R to P was 2:1 (Z-R/P_2:1), the three-phase contact angle was 90.68°, and the wettability of the particles was close to neutral. Rheological analysis showed that the emulsion formed an elastic gel structure. FTIR spectra indicated that there was a hydrogen bond and electrostatic interaction between Z-R and P. The disappearance of characteristic infrared peaks of corn oil was due to a dense protective film formed on the surface of oil drops by Z-R/P_2:1 particles, which was confirmed by confocal laser scanning microscopy. The emulsion stabilized by Z-R/P_2:1 had excellent physical stability at a wide range of pH values (4-9), salt ion concentrations (0.04-0.15 mol·L^-1) and storage times (0-30 days). The anti-lipid oxidation ability of the emulsion was outstanding; after storage for 14 days at room temperature, the MDA content in the emulsion was only 123.85 μmol/kg oil. In conclusion, the Z-R/P_2:1 particles prepared in this study can effectively stabilize a Pickering emulsion and expand the usability of the method for constructing antioxidant Pickering emulsions.

Foaming and Physicochemical Properties of Commercial Protein Ingredients Used for Infant Formula Formulation

Protein, as one of the main ingredients for infant formula, may be closely related to the undesirable foam formed during the reconstitution of infant formula. Demineralized whey powder (D70 and D90), whey protein concentrate (WPC), and skimmed milk powder (SMP) are the four protein ingredients commonly used in infant formula formulation. The foaming and physicochemical properties of these four protein ingredients from different manufacturers were analyzed in the present study. Significant differences (p < 0.05) in foaming properties were found between the samples from different manufacturers. SMP showed a highest foaming capacity (FC) and foam stability (FS), followed by D70, D90, and WPC. Although the protein composition was similar based on reducing SDS-PAGE, the aggregates varied based on non-reducing SDS-PAGE, probably resulting in the different foaming properties. Particle size, zeta potential, and solubility of the protein ingredients were assessed. The protein structure was evaluated by circular dichroism, surface hydrophobicity, and free sulfhydryl. Pearson’s correlation analysis demonstrated that FC and FS were positively correlated with random coil (0.55 and 0.74), β-turn (0.53 and 0.73), and zeta potential (0.55 and 0.51) but negatively correlated with β-strand (−0.56 and −0.71), free sulfhydryl (−0.56 and −0.63), particle size (−0.45 and −0.53), and fat content (−0.50 and −0.49). The results of this study could provide a theoretical guidance for reducing formation of foam of infant formula products during reconstitution.

Molecular structural modification of β-conglycinin using pH-shifting with ultrasound to improve emulsifying properties and stability

This present work underlines the effect of pH-shifting at pH 2 and pH 12 individually or combined with ultrasound treatment to modify the molecular structure of β-conglycinin (7S) on its emulsifying properties and stability. Fourier transform infrared (FTIR) spectroscopy and intrinsic fluorescence spectroscopy showed that pH-shifting improves the molecular structure of 7S, while ultrasound further promotes structural changes. In particular, the pH-shifting at pH 12 combined with ultrasound treatment (U-7S-12) resulted in more significant changes than the pH-shifting at pH 2 combined with ultrasound (U-7S-2). U-7S-12 showed a significant reduction in protein particle size from 152 to 34.77 nm and a relatively smooth protein surface compared to 7S. The protein had the highest surface hydrophobicity and flexibility at 81,560.0 and 0.45, respectively, and the free sulfhydryl content from 1.57 to 2.02 μmol/g. In addition, we characterized the emulsions prepared after 7S treatment. The single or combined treatment increased the interfacial protein adsorption of the samples, which showed lower viscosity and shear stress compared to 7S. The U-7S-12 emulsion exhibited the highest emulsifying properties and was more stable than other emulsions under creaming, heating, and freeze-thaw conditions. In summary, the concerted action of pH-shifting and ultrasound can modify the structure, and combined alkaline pH-shifting and ultrasound treatment can further improve the emulsifying properties and stability of 7S.

Development of high-internal-phase emulsions stabilized by soy protein isolate-dextran complex for the delivery of quercetin

BACKGROUND

Protein-polysaccharide complexes have been widely used to stabilize high-internal-phase emulsion (HIPEs). However, it is still unknown whether soy protein isolate-dextran (SPI-Dex) complexes can stabilize HIPEs or what is the effect of Dex concentration on the HIPEs. Furthermore, the non-covalent interaction mechanism between SPI and Dex is also unclear. Therefore, we fabricated SPI-Dex complexes and used them to stabilize HIPEs-loaded quercetin and explore the interaction mechanism between SPI and Dex, as well as the effect of Dex concentration on the particle size, ζ-potential, microstructure, rheology, quercetin encapsulation efficiency, and gastrointestinal fate of the HIPEs.

RESULTS

Spectral analysis (fourier transform infrared spectroscopy, ultraviolet spectroscopy, and fluorescence spectroscopy) results identified the formation of SPI-Dex complexes, and indicated that the addition of Dex changed the spatial structure of SPI, whereas thermodynamic analysis (ΔH > 0, ΔS > 0) showed that hydrophobic interactions were the main driving forces in the formation of SPI-Dex complexes. Compared with HIPEs stabilized by SPI, the SPI-Dex complex-stabilized HIPEs had smaller particles (3000.33 ± 201.22 nm), as well as higher ζ-potential (-21.73 ± 1.10 mV), apparent viscosities, modulus, and quercetin encapsulation efficiency (98.19 ± 0.14%). In addition, in vitro digestion revealed that SPI-Dex complex-stabilized HIPEs significantly reduced the release of free fatty acid and improved quercetin bioaccessibility.

CONCLUSION

HIPEs stabilized by SPI-Dex complexes delayed the release of free fat acid and improved the bioaccessibility of quercetin, and may be help in designing delivery systems for bioactive substances with specific properties. © 2022 Society of Chemical Industry.

Stability and digestibility of encapsulated lycopene in different emulsion systems stabilized by acid-modified soybean lipophilic protein

BACKGROUND

Owing to the harsh acidic environment of the stomach, acid-resistant emulsion products have wide-ranging applications in the food industry. Herein, natural soybean lipophilic protein (LP) was used to establish coarse emulsions, nanoemulsions, emulsion gels, and high internal phase Pickering emulsions (HIPPE) under acidic conditions. Furthermore, the carrying characteristics of the acid-resistant emulsion system with lycopene were explored.

RESULTS

Comparisons of particle sizes, potentials, microstructures, and rheology of the four carrier systems revealed that HIPPE has a single particle-size distribution, the largest zeta potential, and an elastic gel-like network structure. Comparison of encapsulation rates indicated that HIPPE had the best effect on encapsulating lycopene, reaching approximately 90%. The pH stability, storage stability, and simulated in vitro digestion experiments showed that the four emulsions that were stable under acidic conditions had good acid resistance. Among them, the acid-induced LP-stabilized HIPPE had the best storage stability and superior compatibility with the harsh acidic environment of the stomach, which not only achieved the purpose of delaying the release of lipids but also conferred better protection to lycopene in the gastric tract; moreover, it achieved the best bioavailability.

CONCLUSION

LP-stabilized HIPPE has the best stability and can yield better absorption and utilization of lycopene by the body. The results of this study are helpful for the development of acid-resistant functional emulsion foods that are conducive to the absorption of lycopene. © 2022 Society of Chemical Industry.

Structural modification induced by heat treatments improves the emulsifying attributes of lacquer seed protein isolate

The lacquer seed oil has received extensive attention in the food industry due to its health function, such as regulating blood lipids. But its by-product, lacquer seed meal, is often used as a low-value-added product such as animal feed. Lacquer seed meal contains about 20 % protein, which has amphiphilic properties, and there is limited attention to its emulsifying properties. In this study, the impact of heat treatment on the emulsifying properties of lacquer seed protein isolate (LSPI) was investigated. The EAI and ESI of the 120 °C heated LSPI increased by 77.1 % and 55.2 %, respectively. The emulsions prepared using heat-modified LSPI (120 °C) further showed lower hydroperoxide, TBARS and protein carbonyl contents (only 61.3 %, 61.0 % and 58.6 % of control) after storage. This result indicates that heat-treated LSPI retarded lipid and protein oxidation in LSPI-stabilized emulsions during storage. Changes in protein structure showed that increasing heating temperature resulted in the depolymerization of tertiary structure, higher surface hydrophobicity and lower contents of α-helix of LSPI. These changes in protein structure made the heated LSPIs have better emulsifying properties. Therefore, these findings developed a new use of LSPI and greatly enhanced the potential of LSPI as a natural emulsifier in the food industry.

Effects of Heat Treatment Duration on the Electrical Properties, Texture and Color of Polymerized Whey Protein

In this research effects of heat treatment duration on the electrical properties (zeta potential and conductivity), texture and color of polymerized whey protein (PWP) were analyzed. Whey protein solutions were heated for 30 min to obtain single-heated polymerized whey protein (SPWP). After cooling to room temperature, the process was repeated to obtain double-heated polymerized whey protein (DPWP). The largest agglomeration was demonstrated after 10 min of single-heating (zeta potential recorded as -13.3 mV). Single-heating decreased conductivity by 68% and the next heating cycle by 54%. As the heating time increased, there was a significant increase in the firmness of the heated solutions. Zeta potential of the polymerized whey protein correlated with firmness, consistency, and index of viscosity, the latter of which was higher when the zeta potential (r = 0.544) and particle size (r = 0.567) increased. However, there was no correlation between zeta potential and color. This research has implications for future use of PWP in the dairy industry to improve the syneretic, textural, and sensory properties of dairy products.

Eugenol nanoemulsion inactivates Listeria monocytogenes, Salmonella Enteritidis, and Escherichia coli O157:H7 on cantaloupes without affecting rind color

Listeria monocytogenes, Salmonella Enteritidis, and Escherichia coli O157:H7 are the major foodborne pathogens that have been implicated in outbreaks related to consumption of contaminated cantaloupes. Current chlorine-based decontamination strategies are not completely effective for inactivating the aforementioned pathogens on cantaloupes, especially in the presence of organic matter. This study investigated the efficacy of eugenol nanoemulsion (EGNE) wash treatments in inactivating L. monocytogenes, Salmonella spp., and E. coli O157:H7 on the surface of cantaloupes. In addition, the efficacy of EGNE in inhibiting the growth of the three pathogens on cantaloupes during refrigerated and room temperature storage of 5 days was investigated. Moreover, the effect of EGNE wash treatment on cantaloupe color was assessed using a Miniscan® XE Plus. The EGNE was prepared with either Tween 80 (TW) or a combination of Gum arabic and Lecithin (GA) as emulsifiers. The cantaloupe rind was washed with EGNE (0.3, 0.6, and 1.25%), in presence or absence of 5% organic load, for 1, 5, or 10 min at 25°C. Enumeration of surviving pathogens on cantaloupe was performed by serial dilution and plating on Oxford, XLD or SMA agar followed by incubation at 37°C for 24–48 h. EGNE-GA and EGNE-TW wash significantly reduced all three pathogens by at least 3.5 log CFU/cm2 as early as 5 min after treatment. EGNE-GA at 1.25% inactivated L. monocytogenes, E. coli O157:H7 and S. Enteritidis on cantaloupes to below the detectable limit within 5 and 10 min of treatment, respectively (~4 log CFU/cm2, P &lt; 0.05). EGNE treatments significantly reduced the survival of L. monocytogenes, S. Enteritidis, and E. coli O157:H7 on cantaloupe by at least 6 log CFU/cm2 at day 5 of storage at 25 and 4°C (P &lt; 0.05). Presence of organic matter did not modulate the antimicrobial efficacy of nanoemulsion treatments (P &gt; 0.05). EGNE treatments did not affect the rind color of cantaloupes (P &gt; 0.05). In conclusion, eugenol nanoemulsions could potentially be used as a natural sanitizer to inactivate foodborne pathogens on cantaloupes. Further investigations in an industry setting are warranted.

Pectin Stabilized Fish Gelatin Emulsions: Physical Stability, Rheological, and Interaction Properties

Pectin, a kind of natural polysaccharide, shows the attractive potential as a natural stabilizer for protein emulsion. The aim of this study is to investigate the effect of pectin on the physical stability, rheology, interface, and interaction properties of the fish gelatin (FG) emulsion, as pectin was utilized to improve the stability of FG, fish oil emulsion. During the study, when pH &lt; 6, the FG-pectin emulsion displayed better storage stability and salinity tolerance. Analyzing the result, pectin could avoid phase separation at the freeze-thaw process and prevent the liquid-gel transition of FG emulsions during storage. On the other hand, when pH ≥ 6, the emulsion displayed high viscosity due to the complex flocculation and stratified during long-term storage. Electrostatic interactions, hydrophobic interactions, and hydrogen bonding of the FG-pectin complexes in the emulsion were all reduced. Overall, pectin improved the stability of FG emulsions through electrostatic repulsion, hydrophobic interactions, and steric hindrance.

Emulsifying properties and bioavailability of clove essential oil Pickering emulsions stabilized by octadecylaminated carboxymethyl curdlan

In the present study, clove essential oil (CEO) Pickering emulsions were stabilized by octadecylamine-modified carboxymethyl curdlan (CMCD-ODA) at different pH values. The droplet size and negatively charged zeta potential of the CMCD-ODA emulsions decreased as the pH increased from 3.0 to 11.0. Rheology results indicated that the CMCD-ODA polymer/emulsion prepared at pH 5.0 showed higher apparent viscosity and viscoelasticity than other pH conditions, which might prevent droplets from flocculating. The Pickering emulsions obtained at pH 5.0 were spherical droplets with a uniform size distribution and a mean diameter of 9.54 μm, and they exhibited excellent stability during 28 days of storage. The morphological structures of the emulsions investigated by confocal laser scanning microscopy and scanning electron microscopy indicated that the CMCD-ODA Pickering emulsion obtained at pH 5.0 was stabilized by loading amphiphilic CMCD-ODA polymer around the spherical oil droplets and forming a weak gel network structure. The CEO-loaded CMCD-ODA emulsions had higher antioxidant capacity than free CEO after 28 days of storage at pH 5.0. Given the good emulsion stability, antioxidant activity, and great antibacterial effect, the CEO-loaded carboxymethyl curdlan Pickering emulsion has promising applications in food, cosmetic, and biomedicine industries.