Ultra-High Pressure Homogenization improves oxidative stability and interfacial properties of soy protein isolate-stabilized emulsions

Investigating the effects of oil type, emulsifier type, and emulsion particle size on textured fibril soy protein emulsion-filled gels and soybean protein isolate emulsion-filled gels

The effects of oil type, emulsifier type, and emulsion particle size on the texture, gel strength, and rheological properties of SPI emulsion-filled gel (SPI-FG) and TFSP emulsion-filled gel (TFSP-FG) were investigated. Using soybean protein isolate or sodium caseinate as emulsifiers, emulsions with cocoa butter replacer (CBR), palm oil (PO), virgin coconut oil (VCO), and canola oil (CO) as oil phases were prepared. These emulsions were filled into SPI and TFSP gel substrates to prepare emulsion-filled gels. Results that the hardness and gel strength of both gels increased with increasing emulsion content when CBR was used as the emulsion oil phase. However, when the other three liquid oils were used as the oil phase, the hardness and gel strength of TFSP-FG decreased with the increasing of emulsion content, but those of SPI-FG increased when SPI was used as emulsifier. Additionally, the hardness and gel strength of both TFSP-FG and SPI-FG increased with the decreasing of mean particle size of emulsions. Rheological measurements were consistent with textural measurements and found that compared with SC, TFSP-FG, and SPI-FG showed higher G' values when SPI was used as emulsifier. Confocal laser scanning microscopy (CLSM) observation showed that the distribution and stability of emulsion droplets in TFSP-FG and SPI-FG were influenced by the oil type, emulsifier type and emulsion particle size. SPI-stabilized emulsion behaved as active fillers in SPI-FG reinforcing the gel matrix; however, the gel matrix of TFSP-FG still had many void pores when SPI-stabilized emulsion was involved. In conclusion, compared to SPI-FG, the emulsion filler effect that could reinforce gel networks became weaker in TFSP-FG.

Young apple polyphenols confer excellent physical and oxidative stabilities to soy protein emulsions for effective β-carotene encapsulation and delivery

Protein emulsions' poor physical and oxidative stabilities restrict their use in functional foods. Soy protein isolate (SPI) emulsions' physical stability was enhanced by adding young apple polyphenols (YAP) in this study, but decreased when YAP was 0.12%. YAP binding prefolded SPI's structure, which promotes efficient SPI stacking at the interface. YAP also improved SPI emulsions' oxidation resistance in a dose-dependent manner. SPI-YAP interaction promoted more YAP adsorption (>80%) at the interface, which increased emulsions' antioxidant capacities twofold. Furthermore, over 90% of unsaturated fatty acids were preserved, and the oxidation of lipid-SPI-β-carotene appeared to be reduced as YAP increased. In addition, SPI-YAP emulsions were effective in encapsulating and safeguarding β-carotene during emulsion storage and in vitro digestion, leading to a delayed and maximum release of β-carotene. This study improves the understanding of polyphenols inhibition on lipid-protein oxidation through interface strengthening and broadens the potential applications of YAP and SPI in functional foods.

Encapsulation and characterization of soy protein-based ω-3 medium- and long- chain triacylglycerols microencapsulated with diverse homogenization techniques for improving oxidation stability

Recently, MLCTs have attracted considerable attention as a potential alternative to traditional oils due to their suppressive effect on fat accumulation and insulin sensitivity. In this study, the microcapsules of MLCTs with superior performance were fabricated through different homogenization processes to overcome the limitations of ω-3 medium- and long- chain triacylglycerols (MLCTs), including poor stability and prone oxidation. Additionally, the impact of various homogenization techniques, namely, high-pressure, ultrasound, and cavitation jet, on the particle structure, encapsulation efficiency, and oxidation stability of microcapsules (MLCTs) was investigated. The MLCTs microcapsules fabricated through high-pressure homogenization had a smaller particle size of 295.12 nm, lower PDI of 0.24, and a higher zeta-potential absolute value of 32.65, which significantly improved their dispersion and encapsulation efficiency, reaching 94.56 % after the spray-drying process. Furthermore, the low moisture content and superior storage stability of MLCTs microcapsules have the potential to serve as carriers of liposoluble actives.

Shade of Innovative Food Processing Techniques: Potential Inducing Factors of Lipid Oxidation

With increasing environmental awareness and consumer demand for high-quality food products, industries are strongly required for technical innovations. The use of various emerging techniques in food processing indeed brings many economic and environmental benefits compared to conventional processes. However, lipid oxidation induced by some "innovative" processes is often "an inconvenient truth", which is scarcely mentioned in most studies but should not be ignored for the further improvement and optimization of existing processes. Lipid oxidation poses a risk to consumer health, as a result of the possible ingestion of secondary oxidation products. From this point of view, this review summarizes the advance of lipid oxidation mechanism studies and mainly discloses the shade of innovative food processing concerning lipid degradation. Sections involving a revisit of classic three-stage chain reaction, the advances of polar paradox and cut-off theories, and potential lipid oxidation factors from emerging techniques are described, which might help in developing more robust guidelines to ensure a good practice of these innovative food processing techniques in future.

The Emulsifying Properties, In Vitro Digestion Characteristics and Storage Stability of High-Pressure-Homogenization-Modified Dual-Protein-Based Emulsions

The droplet size, zeta potential, interface protein adsorption rate, physical stability and microrheological properties of high-pressure-homogenization (HPH)-modified, dual-protein-based whey-soy (whey protein isolate-soy protein isolate) emulsions containing different oil phase concentrations (5%, 10% and 15%; w/w) were compared in this paper. The in vitro digestion characteristics and storage stability of the dual-protein emulsions before and after HPH treatment were also explored. The results show that with an increase in the oil phase concentration, the droplet size and interface protein adsorption rate of the untreated dual-protein emulsions increased, while the absolute value of the zeta potential decreased. When the oil phase concentration was 10% (w/w), HPH treatment could significantly reduce the droplet size of the dual-protein emulsion, increase the interface protein adsorption rate, and improve the elasticity of the emulsion. Compared with other oil phase concentrations, the physical stability of the dual-protein emulsion containing a 10% (w/w) oil phase concentration was the best, so the in vitro digestion characteristics and storage stability of the emulsions were studied. Compared with the control group, the droplet size of the HPH-modified dual-protein emulsion was significantly reduced after gastrointestinal digestion, and the in vitro digestibility and release of free amino groups both significantly increased. The storage stability results show that the HPH-modified dual-protein emulsion showed good stability under different storage methods, and the storage stability of the steam-sterilized dual-protein emulsion stored at room temperature was the best. These results provide a theoretical basis for the development of new nutritional and healthy dual-protein liquid products.

Ultrasonic and homogenization: An overview of the preparation of an edible protein-polysaccharide complex emulsion

Emulsion systems are extensively utilized in the food industry, including dairy products, such as ice cream and salad dressing, as well as meat products, beverages, sauces, and mayonnaise. Meanwhile, diverse advanced technologies have been developed for emulsion preparation. Compared with other techniques, high-intensity ultrasound (HIUS) and high-pressure homogenization (HPH) are two emerging emulsification methods that are cost-effective, green, and environmentally friendly and have gained significant attention. HIUS-induced acoustic cavitation helps in efficiently disrupting the oil droplets, which effectively produces a stable emulsion. HPH-induced shear stress, turbulence, and cavitation lead to droplet disruption, altering protein structure and functional aspects of food. The key distinctions among emulsification devices are covered in this review, as are the mechanisms of the HIUS and HPH emulsification processes. Furthermore, the preparation of emulsions including natural polymers (e.g., proteins-polysaccharides, and their complexes), has also been discussed in this review. Moreover, the review put forward to the future HIUS and HPH emulsification trends and challenges. HIUS and HPH can prepare much emulsifier-stable food emulsions, (e.g., proteins, polysaccharides, and protein-polysaccharide complexes). Appropriate HIUS and HPH treatment can improve emulsions' rheological and emulsifying properties and reduce the emulsions droplets' size. HIUS and HPH are suitable methods for developing protein-polysaccharide forming stable emulsions. Despite the numerous studies conducted on ultrasonic and homogenization-induced emulsifying properties available in recent literature, this review specifically focuses on summarizing the significant progress made in utilizing biopolymer-based protein-polysaccharide complex particles, which can provide valuable insights for designing new, sustainable, clean-label, and improved eco-friendly colloidal systems for food emulsion. PRACTICAL APPLICATION: Utilizing complex particle-stabilized emulsions is a promising approach towards developing safer, healthier, and more sustainable food products that meet legal requirements and industrial standards. Moreover, the is an increasing need of concentrated emulsions stabilized by biopolymer complex particles, which have been increasingly recognized for their potential health benefits in protecting against lifestyle-related diseases by the scientific community, industries, and consumers.

Effect of heat treatment on the physical stability, interfacial composition and protein-lipid co-oxidation of whey protein isolate-stabilised O/W emulsions

This work aimed to investigate the effects of heat treatments at different temperatures (60, 70 and 90 °C, expressed as HT-60, HT-70 and HT-90) on interfacial composition and protein-lipid co-oxidation in whey protein isolate (WPI)-stabilised O/W emulsions during storage. Compared with control group, all heated emulsions exhibited weaker physical stability over 10 days of storage, which verified by the increased droplet size, as well as decreased adsorbed protein levels and absolute ζ-potential values. Moreover, proteins recovered from the HT-90 emulsion showed the highest fluorescence intensity and red-shift of the maximum emission wavelength, indicating partial unfolding of the protein structure. Meanwhile, severe changes in protein structure were also observed in the HT-70 and HT-90 emulsions, which clearly verified by the degradation of bovine serum albumin, α-lactalbumin and β-lactoglobulin. Furthermore, HT-70 and HT-90 emulsions showed lower levels of lipid hydroperoxides and thiobarbituric acid reactive substances. In contrast, the recovered proteins were subject to severe oxidative stress as indicated by carbonyl and N'-formyl-L-kynurenine. Hierarchical cluster and correlation analysis implied that the process of protein-lipid co-oxidation is inevitable, but it can be retarded by heat treatment. Our results clearly revealed the relevance among heat treatment, interfacial adsorption property, and the protein-lipid co-oxidation of O/W emulsions.

Parameter control, characterization and stability of soy protein emulsion prepared by microfluidic technology

A flow-focusing microfluidic device driven by pressure was employed in soy protein emulsions with uniform droplet size and good morphology. The results suggested that pressure was an essential factor for droplet formation. The optimum parameter was at a continuous phase pressure of 140 mbar and dispersed phase pressure of 80 mbar. Under this condition, the droplet formation time was shortened to 0.20 s, with average sizes of 39-43 μm and coefficient of variation of about 2 %. Emulsion stability was improved with increasing soy protein isolate (SPI) concentrations. At SPI concentrations higher than 20 mg/mL, the emulsions exhibited improved stability against changes in temperature, pH and salt concentration. Emulsions prepared in this manner exhibited superior oxidative stability than those prepared by conventional methods utilizing homogenizers. This study showed that microfluidic technology can be applied to soy protein emulsions as an effective tool for preparing droplets with uniform size and enhanced stability.

Recent Trends in Improving the Oxidative Stability of Oil-Based Food Products by Inhibiting Oxidation at the Interfacial Region

In recent years, new approaches have been developed to limit the oxidation of oil-based food products by inhibiting peroxidation at the interfacial region. This review article describes and discusses these particular approaches. In bulk oils, modifying the polarity of antioxidants by chemical methods (e.g., esterifying antioxidants with fatty alcohol or fatty acids) and combining antioxidants with surfactants with low hydrophilic–lipophilic balance value (e.g., lecithin and polyglycerol polyricinoleate) can be effective strategies for inhibiting peroxidation. Compared to monolayer emulsions, a thick interfacial layer in multilayer emulsions and Pickering emulsions can act as a physical barrier. Meanwhile, high viscosity of the water phase in emulsion gels tends to hinder the diffusion of pro-oxidants into the interfacial region. Furthermore, applying surface-active substances with antioxidant properties (such as proteins, peptides, polysaccharides, and complexes of protein-polysaccharide, protein-polyphenol, protein-saponin, and protein-polysaccharide-polyphenol) that adsorb at the interfacial area is another novel method for enhancing oil-in-water emulsion oxidative stability. Furthermore, localizing antioxidants at the interfacial region through lipophilization of hydrophilic antioxidants, conjugating antioxidants with surfactants, or entrapping antioxidants into Pickering particles can be considered new strategies for reducing the emulsion peroxidation.

Effect of ultrasonic homogenization on crude oil-water emulsion stability

This research aims to evaluate the effect of ultrasonic processing parameters (power and sonication time), emulsion characteristics (water salinity and pH) and their interaction on oil-in-water emulsion stability for Cold Lake Blend (CLB) crude oil. Response surface methodology was used to design experimental runs, in which the parameters were investigated at five levels. Emulsion stability was evaluated by measuring creaming index, emulsion turbidity and microscopic image analysis. The effect of crude oil condition (fresh and weathered) on the emulsion stability was also investigated at the optimum sonication parameters and emulsion characteristics. The optimum condition was found at a power level of 76-80 W, sonication time of 16 mins, water salinity of 15 g/L NaCl, and pH of 8.3. Increasing sonication time beyond the optimum value had adverse effect on the emulsion stability. High water salinity (> 20 g/L NaCl) and pH (> 9) decreased the emulsion stability. These adverse effects intensified at higher power levels (> 80-87 W) and longer sonication times (> 16 mins). Interaction of parameters showed that the required energy to generate stable emulsion was within 60 - 70 kJ. Emulsion with fresh crude oil was more stable than those generated with the weathered oil.

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

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

Physical and oxidative stability of astaxanthin microcapsules prepared with liposomes

BACKGROUND

Oil bodies (OBs) are a kind of natural and stable oil nucleate microcapsule in which the triglyceride matrix can be used as an appropriate carrier of hydrophobic molecules. Astaxanthin has high antioxidant properties but is extremely sensitive to oxidation, causing the loss of its bioactive properties.

RESULTS

The purpose of this study was to clarify the effects of environmental factors (light, oxygen, temperature, and pH) on the physical and oxidative stability of astaxanthin microcapsules prepared with peanut oil bodies (POBs). After 14 days of storage, the retention rate of astaxanthin in peanut oil microcapsules (POMs) was significantly increased. The astaxanthin retention rate of POMs stored under light conditions was higher than under dark conditions. Similarly, the retention rate of astaxanthin in POMs was significantly increased during vacuum storage. The astaxanthin retention rate was also the highest when POMs were stored at 4 °C, whereas it was the lowest at pH 3.0.

CONCLUSION

The experiment demonstrated that microcapsulation could improve the astaxanthin retention rate and storage stability, and recombinant OBs were potential ideal wall materials for astaxanthin embedding. © 2022 Society of Chemical Industry.

The effect of microfluidization pressure on the physical stability of vitamin A in oil-in-water emulsions

In this study, vitamin A was encapsulated within oil-in-water emulsions by high-pressure microfluidization prepared using phosphate buffer (90%), corn oil (10%), and whey protein isolate (2%) as an emulsifier. The influence of microfluidization pressure (10, 50, 100, 200 MPa) on the particle size, zeta potential, and the physical and chemical stability of emulsions was evaluated. The physical stability of emulsion was determined by multiple light scattering technique. The content of vitamin A was measured by HPLC–DAD during an accelerated storage test at 40 °C during 4 weeks. The color of the samples was monitored using a colorimeter. The results showed that the lowest particle size distribution and the highest absolute value of zeta potential on the droplets’ surface charge were obtained by applying a pressure of 100 MPa. Nanoemulsions prepared at 100 MPa also showed the highest colloidal stability. However, higher microfluidization pressure (up to 200 MPa) had a negative impact on the prepared emulsion’s stability. The results of chemical stability by HPLC measurements during storage time were in agreement with the results of physical stability and color change.

Comparison of oil-in-water emulsions prepared by ultrasound, high-pressure homogenization and high-speed homogenization

This study was designed to compare the properties of myofibrillar protein (MP) stabilized soybean oil-in-water emulsions fabricated by ultrasound-assisted emulsification (UAE), high-pressure homogenization (HPH) and high-speed homogenization (HSH). The emulsion properties, droplet characteristics, interfacial proteins, protein exposure extent, microrheological properties, multiple light scattering results, and 7 d storage stabilities of the three emulsions were specifically investigated. Our results indicate that UAE and HPH were better emulsification methods than HSH to obtain high-quality emulsions with higher emulsifying activity index (UAE 20.73 m²·g^-1, HPH 11.76 m²·g^-1 and HSH 6.80 m²·g^-1), whiteness (UAE 81.05, HPH 80.67 and HSH 74.09), viscosity coefficient (UAE 0.44 Pa·sⁿ, HPH 0.49 Pa·sⁿ and HSH 0.22 Pa·sⁿ), macroscopic viscosity index (UAE 2.31 nm^-2·s, HPH 0.38 nm^-2·s and HSH 0.34 nm^-2·s), and storage stability, especially for the UAE. Furthermore, UAE was a more efficient emulsification method than HPH to prepare the fine MP-soybean oil emulsion. The protein-coated oil droplets were observed in the three emulsions. The emulsion droplet size of the UAE-fabricated emulsion was the lowest (0.15 μm) while the interfacial protein concentration (93.37%) and the protein exposure extent were the highest among the three emulsions. During the 7 d storage, no separation was observed for the UAE-fabricated emulsion, while the emulsions fabricated by HPH and HSH were separated after storage for 5 d and 2 h. Therefore, this work suggests that UAE could be a better method than HPH and HSH to fabricate MP-soybean oil emulsion.

Quality Attributes of Ultra-High Temperature-Treated Model Beverages Prepared with Faba Bean Protein Concentrates

The objective of this research was to develop a model faba bean drink with a high concentration of protein (>4% w/w). The protein molecular weights and frequency for both faba and soy were assessed using SDS-PAGE. Results showed similarities in the protein molecular weight of both faba and soy (mainly 11S globulin ~Glycinin and 7S globulin ~β-conglycinin). Thus, faba can be considered as a potential soy replica in plant-based milk beverages. Oil-in-water emulsions (5-8% w/w available protein) were prepared using faba bean protein concentrate (FPC), 1% sunflower oil, and 0.2% sunflower lecithin. These emulsions were used as model beverages and were further investigated for UHT processibility, stability, and physicochemical properties. The physicochemical properties of emulsions at various processing stages viz., coarse emulsification, homogenisation, and UHT, were measured. An increase in the protein concentration and thermal treatment resulted in an increased oil droplet size, coalescence and flocculation, and protein aggregation. Lower protein concentrations viz., 5-6%, showed greater negative ζ-potential, and thereby, high dispersibility through enhanced electrostatic repulsions than those of higher concentrations (7-8%). Furthermore, an increase in protein concentration and UHT treatment resulted in an increased creaming index. In total, 21 different volatile compounds were detected and quantified, representing different chemical classes, namely alcohols, aldehydes, ketones, esters, furan, and acids. These volatiles have major consequences for the overall flavour chemistry of the model beverage product. Overall, this study showed the potential for application of faba bean as a protein source in UHT-treated legume-based beverages and identified areas for further development.

Enhancement of physicochemical and encapsulation stability of O1/W/O2 multiple nanoemulsions loaded with coenzyme Q10 or conjugated linoleic acid by incorporating polyphenolic extract

Multiple O1/W/O2 nanoemulsions and O1/W nanoemulsions fortified with CLA or CoQ10 were produced using extra virgin olive or olive pomace oil and were also incorporated with polyphenols extracted from olive kernel to enhance their kinetic and chemical stability. They were prepared using a high-speed ultrasonic homogenizer. Specifically, nanoemulsions with 6 wt% lipid phase and 6 wt% non-ionic emulsifier (Tween 40) were produced and they demonstrated a droplet diameter >200 nm and high encapsulation stability during 30 days of storage at 4 °C or 25 °C. The incorporation of CLA or CoQ10 and polyphenolic compounds facilitated the homogenization of emulsions, reducing the droplet size and enhancing their chemical stability, and their bioactive retention values were >79%. O1/W/O2 nanoemulsions were produced using a mixture of non-ionic emulsifiers (Span 20 and Tween 40) and the O1/W enriched nanoemulsion as the dispersed phase. All multiple emulsions showed a bimodal droplet size distribution and Newtonian behavior while polyphenols facilitated their homogenization. Both vegetable oils resulted in samples with high kinetic and chemical stability; the bioactive retention values were found to be >80% at the end of 30 days of storage at 4 °C or 25 °C. Extra virgin olive oil resulted in more stable nanoemulsions in regards to kinetic and chemical stability at 4 °C, showing limited creaming and sedimentation boundary. Multiple nanoemulsions with the lowest initial droplet size presented the lowest droplet diameter growth and phase separation and the highest retention values. By comparing O1/W nanoemulsions and O1/W/O2 nanoemulsions, we noted that the reduction in the total phenolic content and antioxidant activity during storage was higher in the O1/W type. However, both delivery systems protected CLA and CoQ10 presenting high retention during storage. FTIR spectra before and after ultrasonic homogenization indicated that the sonication process did not significantly affect the lipid phase of O1/W/O2 nanoemulsions.

Buttermilk as Encapsulating Agent: Effect of Ultra-High-Pressure Homogenization on Chia Oil-in-Water Liquid Emulsion Formulations for Spray Drying

Functional foods are highly demanded by consumers. Omega-3 rich oil and commercial buttermilk (BM), as functional components, used in combination to produce emulsions for further drying may facilitate the incorporation to foods. Ultra-high-pressure homogenization (UHPH) has a great potential for technological and nutritional aspects in emulsions production. The present study aimed to examine the potential improvement of UHPH technology in producing buttermilk-stabilized omega-3 rich emulsions (BME) for further drying, compared with conventional homogenization. Oil-in-water emulsions formulated with 10% chia: sunflower oil (50:50); 30% maltodextrin and 4 to 7% buttermilk were obtained by using conventional homogenization at 30 MPa and UHPH at 100 and 200 MPa. Particle size analysis, rheological evaluation, colloidal stability, zeta-potential measurement, and microstructure observations were performed in the BME. Subsequent spray drying of emulsions were made. As preliminary approximation for evaluating differences in the homogenization technology applied, encapsulation efficiency and morphological characteristics of on spray-dried emulsions (SDE) containing 21.3 to 22.7% oil content (dry basis) were selected. This study addresses the improvement in stability of BME treated by UHPH when compared to conventional homogenization and the beneficial consequences in encapsulation efficiency and morphology of SDE.

Effects of Cavitation Jet Treatment on the Structure and Emulsification Properties of Oxidized Soy Protein Isolate

This study examined the ability of cavitation jet processing to regulate the oxidation concentrations with 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) (0.2, 1, and 5 mmol/L) and the structure and emulsification of soy protein isolate (SPI). The tested properties included particle size distribution, hydrophobic properties (sulfhydryl group (SH) and disulfide bond (S-S) contents, surface hydrophobicity (H0)), emulsifying properties (particle size and ζ-potential of emulsions, emulsification activity index (EAI), and emulsification stability index (ESI)), as well as conformational characteristics. The high shear force of cavitation jet treatment reduced the particle size of oxidized SPI and distributed uniformly. Cavitation jet (90 MPa)-treated SPI (AAPH with 1 mmol/L) demonstrated a high H0 (4688.70 ± 84.60), high EAI (71.78 ± 1.52 m2/g), and high ESI (86.73 ± 0.97%). The ordered secondary structure (α-helix and β-turn content) of SPI was enhanced by the cavitation jet. Meanwhile, the distribution of SPI-oxidized aggregates was observed under an atomic force microscope. Therefore, cavitation jet processing combined with oxidation treatment is an effective method to improve the characteristics of SPI and has potential industrial application prospects.

Solubility and aggregation of soy protein isolate induced by different ionic liquids with the assistance of ultrasound

The aim of this study was to evaluate the effects of ionic liquids (ILs) and ultrasound on the solubility and aggregation behavior of soy protein isolate (SPI). A variety of ILs were tested. Results showed that changes in cation or anion altered the physicochemical properties of ionic liquids, which in turn influenced the solubility of SPI. High concentration of ILs resulted in the formation of insoluble aggregates, which lead to the decrease of solubility. In most of the cases, ultrasound pretreatment had a considerable impact on the solubility and aggregation of SPI. The solubility of SPI processed by combination of 1 mg/mL 1-butyl-2,3-dimethyl imidazolium chloride ([BDMIM]Cl) and ultrasound changed remarkably compared with single ultrasound and single [BDMIM]Cl processing, which was increased by 71.8% compared with that of control (P < .05). Changes in particle size, intrinsic fluorescence spectra and free sulfhydryl (SH) groups indicated that the structure of SPI refolded and reaggregated after the ultrasound and ILs pretreatments. Combined ultrasound and 1 mg/mL [BDMIM]Cl pretreatment showed a synergistic effect on changing the SPI microstructure. In conclusion, ultrasound-assisted ILs could be an effective modification method for the globular proteins.

The role of breadfruit OSA starch and surfactant in stabilizing high-oil-load emulsions using high-pressure homogenization and low-frequency ultrasonication

This study aimed to investigate the role of modified breadfruit starch in the presence of Tween 80 for stabilizing the oil-in-water emulsions. An ultra turrax homogenizer was used to produce coarse emulsions, followed by high-pressure homogenization (HPH) or low-frequency ultrasonication (LFU) for fine emulsions. The breadfruit starch was chemically modified using octenyl succinic anhydride (OSA) to produce modified breadfruit OSA starch (BOSA). The dispersed phase was a mixture of palm and lemon oil in a 9:1 ratio. Two BOSA (1% and 2%), three oil concentrations (10%, 25%, and 40%) and Tween 80 (1% of the total amount of oil) were examined based on the emulsion stability. The Fourier transform infrared spectroscopy (FTIR) indicated that starch modification was successful (Degree of Substitution-DS, 0.0241). The most stable coarse emulsions contained 40% oil and 2% BOSA starch. The same formula produced fine emulsions that remained stable for over 42 days, regardless of the homogenization method. BOSA starch and Tween 80 exhibit a mixed stabilization effect on the oil-in-water emulsions. HPH produced more uniformly sized emulsion droplets when compared with those produced using LFU.

Influence of Ternary Emulsifier Mixtures on Oxidative Stability of Nanoemulsions Based on Avocado Oil

The aim of this work was to study the effect of two emulsifiers (M1: SL-soy lecithin, Tw80-Tween 80 and CasCa-calcium caseinate and M2: SL-soy lecithin, Tw80-Tween 80 and SE-sucrose esters) on the oxidative stability of avocado oil-based nanoemulsions. Oil-in-water nanoemulsions were prepared using 3.6% w/w of two emulsifier mixtures, which were optimized by mixture experimental design in order to minimize particle size (PS) and polydispersity index (PdI). Then, the oxidative stability of nanoemulsions was evaluated through both an induction period and a quantification of hydroperoxides and thiobarbituric acid reactive species (TBARs) under accelerated storage conditions. The simplex-centroid mixture design showed that PS and PdI varied when proportions of different emulsifiers were modified, obtaining an optimized concentration for each mixture of: 85% SL, 10% Tw80 and 5%CasCa (M1) and 85% SL, 7.4% Tw80 and 7.6% SE (M2) that produced nanoemulsions with PS ~116 nm and PdI < 0.2. Nanoemulsions elaborated with M1 and M2 presented similar particle characteristics and physical stability to the control sample with Tw80. However, M1 nanoemulsions were more stable against lipid oxidation, since they showed the highest induction period and lower formation of hydroperoxides and TBARs during storage.

Stability Mechanism of Two Soybean Protein-Phosphatidylcholine Nanoemulsion Preparation Methods from a Structural Perspective: A Raman Spectroscopy Analysis

Ultrasound treatment and high-pressure homogenization were used to prepare soybean protein (SP)-phosphatidylcholine (PC) nanoemulsions in this study. Nanoemulsions prepared by high-pressure homogenization were more stable. The structural changes of SP and PC under ultrasound treatment and high-pressure homogenization treatment were investigated by Raman spectroscopy. It could be concluded that ultrasound and high-pressure homogenization treatments increased both the content of α-helix and unordered structure but decreased that of β-structures of SP, while the interaction between SP and PC decreased α-helix content and also reduced unordered structure and β-sheet structure. Ultrasound treatment and high-pressure homogenization exposed more tryptophan and tyrosine residues to promote hydrophobic interaction between SP and PC, which was beneficial for stabilizing the nanoemulsion. The SP-PC interaction exerted a more significant effect on side chain structure than those observed under ultrasound treatment and high-pressure homogenization. The dominant g-g-t vibrational mode of the disulfide bond of soybean protein was not appreciably changed by the two preparations. High-pressure homogenization increased the disorder of lipid chains of PC, promoting SP-PC interaction and thereby increasing the stability of the nanoemulsion. The structural change provided a theoretical basis for preparation of two nanoemulsions.

Effect of High Pressure Treatment on Interfacial Properties, Structure and Oxidative Stability of Soy Protein Isolate-Stabilized Emulsions

The effect of high pressure homogenization (HPH) treatment (40 to 200MPa) on the structure, interfacial properties and oxidative stability of soy protein isolate emulsions were investigated. After HPH process, emulsifying activity (EAI) and emulsion stability (ESI) could be improved by 114% and 125%, percentage of protein adsorbed to oil-in-water emulsions significantly improved when the pressure was not more than 160 MPa. SDS-PAGE showed that the HPH caused more low molecular mass subunits as the samples were treated below 160 MPa. FTIR traced the changes of four conformations in the secondary structure. Within a suitable pressure range, the apparent viscosity increased with the increasing of pressure, which reflected shear thinning; rheological measurement of emulsions showed G'>G'', G' and G'' both increased significantly with frequency increasing; emulsions treated by HPH had better oxidative stability. This paper suggested the HPH was a useful method for preparation the highly viscous and stable emulsions.

The aggregation, structures and emulsifying properties of soybean protein isolate induced by ultrasound and acid

The effects of ultrasound and acid on the aggregation, structures and emulsifying properties of soybean protein isolate (SPI) were investigated. Results of solubility showed that ultrasonic treatments at 0.001 M HCl increased the content of soluble SPI. The particle size of soluble aggregates subjected to ultrasonication and acid was initially decreased and then increased with increasing ultrasonic time. Secondary structure analysis, by circular dichroism, indicated lower a-helix and higher random coil amounts in SPI treated with short ultrasonic time, in contrast to the higher a-helix and lower random coil in SPI treated with longer time (more than 20 min). Emulsions prepared with SPI by 10 min of ultrasonication demonstrated significantly (P < 0.05) small droplet sizes and long term stability in comparison with their untreated counterparts. These results highlight that the emulsifying properties of SPI can be significantly improved by the synergistic effect of ultrasound and acid.