Soy Protein Isolate Emulsions Research Articles

Carboxymethyl chitosan-assisted formation of stable soy protein isolate emulsions and their impact on the properties of squid (Dosidicus gigas) surimi gel

In this study, emulsions co-stabilized by soy protein isolate (SPI) and carboxymethyl chitosan (CMCS) were prepared and the effects of different SPI/CMCS ratios (1:0, 4:1, 2:1, 1:1, 1:2, 1:4) on the emulsification characteristics, rheological properties, and microstructure of the composite emulsions were investigated. Subsequently, the effect of these emulsions on the gel properties of squid (Dosidicus gigas) surimi was evaluated. The results indicated that the particle size, interfacial tension and creaming index decreased with increasing CMCS ratio, while the percentage of interfacial protein adsorption increased. The particle size and interfacial tension reached a minimum value, and the interfacial protein adsorption peaked at the optimal SPI/CMCS ratio (1:2, w/w). Additionally, CMCS altered the secondary structure of the protein when complexed with SPI, resulting in a more ordered internal structure. Upon adding an appropriate amount of CMCS-proportioned composite emulsion to the surimi gel, significant improvements were observed in hardness, gel strength, whiteness, immobilized water and decreased drip loss and free water. However, over-addition of CMCS resulted in the quality deterioration of surimi gel. Single SPI emulsions had minimal effects on the surimi gel, indicating the superiority of composite emulsions. In conclusion, the SPI/CMCS composite emulsions enhanced the gel properties of surimi gel, offering new avenues to enhance the quality of emulsified surimi-based products.

Structure, emulsifying and embedding characteristics of soy protein isolate induced by the complexation of carrageenan with different charge groups

Soy protein isolate (SPI) offers high protein, nutritional benefits, and versatile functionality but requires modification due to its environmental sensitivity and functional limitations. To expand the functional characteristics and application scope of SPI, three types of carrageenan (Car) was used to form complexes with SPI. With the addition of carrageenan, the turbidity of SPI at its isoelectric point significantly decreased, and the turbidity curve shifted toward the acidic range. Structural analysis showed that λ-carrageenan significantly reduced the hydrophobicity of SPI from 218 to 150 when combined to SPI at a Car/SPI ratio of 1:5 (P < 0.05). Fourier transform infrared spectra revealed that the electrostatic interaction between ι-carrageenan and SPI was the strongest at a ratio of 1:5. The emulsion stabilized by κ-Car/SPI complexes had the smallest creaming index, with a creaming index of 46.6% after 7 days of storage, which was 33.3% lower than the creaming index of the SPI emulsion (P < 0.05). The ι-Car/SPI complexes exhibited the highest encapsulation efficiency for curcumin, with a value of 80.1%, which was 25.3% higher than the SPI (P < 0.05). This study could provide solutions for the modification of SPI and enhance its application in the food industry.

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.

Improvement of physicochemical properties and quercetin delivery ability of fermentation-induced soy protein isolate emulsion gel processed by ultrasound

This study aimed to investigate the effects of ultrasonic treatment at different powers on the physicochemical properties, microstructure and quercetin delivery capacity of fermentation-induced soy protein isolate emulsion gel (FSEG). The FSEG was prepared by subjecting soy protein isolate (SPI) emulsion to ultrasonic treatment at various powers (0, 100, 200, 300, and 400 W), followed by lactic acid bacteria fermentation. Compared with the control group (0 W), the FSEG treated with ultrasound had higher hardness, water holding capacity (WHC) and rheological parameters. Particularly, at an ultrasonic power of 300 W, the FSEG had the highest hardness (101.69 ± 4.67 g) and WHC (75.20 ± 1.07%) (p < 0.05). Analysis of frequency sweep and strain scanning revealed that the storage modulus (G') and yield strains of FSEG increased after 300 W ultrasonic treatment. Additionally, the recovery rate after creep recovery test significantly increased from 18.70 ± 0.49% (0 W) to 58.05 ± 0.54% (300 W) (p < 0.05). Ultrasound treatment also resulted in an increased β-sheet content and the formation of a more compact micro-network structure. This led to a more uniform distribution of oil droplets and reduced mobility of water within the gel. Moreover, ultrasonic treatment significantly enhanced the encapsulation efficiency of quercetin in FSEG from 81.25 ± 0.62 % (0 W) to 90.04 ± 1.54% (300 W). The bioaccessibility of quercetin also increased significantly from 28.90 ± 0.40% (0 W) to 42.58 ± 1.60% (300 W) (p < 0.05). This study enriches the induction method of soy protein emulsion gels and provides some references for the preparation of fermented emulsion gels loaded with active substances.

Effect of soluble dietary fiber on soy protein isolate emulsion gel properties, stability and delivery of vitamin D3

Emulsion gels with denser network microstructure and stronger mechanical properties have attracted increasing attentions for delivering lipophilic compounds. In this study, the effect of three distinct soluble dietary fiber (inulin (IN), resistant dextrin (RD) and stachyose (ST)) on the rheological, mechanical and microstructural properties of soy protein isolate (SPI) emulsion gel were firstly investigated. Compared with RD and IN, ST significantly accelerated water holding capacity and thermal stability, which exhibited more compact microstructure and more uniform emulsified oil droplets. Subsequently, the stability and bioavailability of vitamin D3 (VD3) in different delivery systems (medium chain triglycerides (MCT) embedding, SPI-ST emulsion embedding, SPI emulsion gel embedding and SPI-ST emulsion gel embedding) were continue evaluated. In vitro simulated digestion experiment demonstrated that the bioaccessibility of encapsulated VD3 in SPI-ST emulsion gel (69.95 %) was much higher than that of free embedding (48.99 %). In vivo pharmacokinetic experiment revealed that the bioavailability of VD3 was significantly enhanced in SPI-ST gel (p < 0.05), with the AUC0-24h value of 25-OH VD3 (the main circulating form of VD3) were 1.34-fold, 1.23-fold higher than that of free embedding, MCT embedding, respectively. These findings provide a possible approach for the development of high protein/fiber functional foods containing enhanced hydrophobic bioactives.

Soy protein isolate emulsion microgel particles for encapsulating oil

Emulsion microgels (EMGs) are a newly developed fat encapsulation system, consisting of one or more emulsion droplets encapsulated in a soft solid in a manner that forms micron-sized particles. Herein, soy protein isolate (SPI) and soybean oil were used to prepare EMGs by shear gelation. EMGs (∼10 μm) were formed and encapsulation efficiencies of up to 99% were achieved by adjusting the oil content and SPI concentration. The size of EMGs produced with 6% (w/v) SPI and 5% (v/v) oil depended on the shear and heating rates. Larger particles (>70 μm) were obtained at low shear (200 s−1) and smaller particles (<20 μm) at higher shear (800 s−1). All EMG systems exhibited shear thinning behavior and the particle size positively corresponded to the heating rate at the same shear rate. In addition, the compactness of the protein network in the SPI gel were improved due to the increased density of the EMG-filled gel's microstructure.

Revealing the interaction mechanism and emulsion properties of carboxymethyl cellulose on soy protein isolate at different pH

In this study, carboxymethyl cellulose (CMC) was introduced to reduce the instability and poor functional properties of soy protein isolate (SPI) in low pH environment. The SPI–CMC systems containing 0–0.5% CMC were prepared at pH 4.0 and 5.0. By exploring the interaction mechanism between them, the optimal formation conditions of the composite systems were revealed. The results showed that CMC was continuously adsorbed on the surface of SPI at pH 4.0, in which electrostatic behavior and hydrogen bonds played an important role. The emulsion properties were the best at 0.4% CMC, and the emulsion activity index (EAI) and emulsion stability index (ESI) were increased by 48.91 m2/g and 91.41 min compared with SPI emulsion. The optical microscope images showed that the emulsion interfacial proteins were formed and the droplets were evenly distributed at 0.4% CMC. At pH 5.0, the stability of the SPI–CMC systems was highly dependent on the steric hindrance and high viscosity of CMC. The EAI and ESI of the emulsion at 0.5% CMC were the highest, which increased by 49.08 m2/g and 83.79 min compared with SPI emulsion. The optical microscope images confirmed that the addition of 0.5% CMC significantly inhibited the leakage of oil droplets. In conclusion, this study provides an effective strategy for stabilizing SPI emulsion in low pH environments, which has important practical application value.

Characterizations of emulsion gel formed with the mixture of whey and soy protein and its protein digestion under in vitro gastric conditions

Partially replacing animal proteins with plant proteins to develop new products has much attention. To get knowledge of their application in emulsion gels, heat-induced composite protein emulsion gels were fabricated using the mixtures of whey protein isolate (WPI) and soy protein isolate (SPI) with the final total protein concentration of 10% (w/w). The water holding capacity (WHC), mechanical and rheological properties and microstructure of mixed protein emulsion gels prepared at different WPI to SPI ratios (100:0, 90:10, 70:30, 50:50, 30:70, 10:90, 0:100, w/w) were investigated. The ratios of WPI to SPI showed little effect on the WHC of the mixed protein emulsion gels (p > 0.05). Increasing the ratio of SPI decreased the hardness and storage modulus (G′) of mixed protein emulsion gels, whereas the porosity of mixed protein emulsion gels in the microstructure increased, as shown by CLSM. Both β-lactoglobulin and α-lactalbumin from WPI and 7 S and 11 S from SPI participated in forming the gel matrix of mixed protein emulsion gels. More protein aggregates existed as the gel matrix filler at the high soy protein levels. Interestingly, the G′ of mixed protein emulsion gels at the WPI to SPI ratio of 50:50 was higher than the sum of G′ of individual WPI and SPI emulsion gels. The whey protein network predominated the gel matrix, while soy protein predominated in the active filling effect. When subjected to an in vitro dynamic gastric digestion model, soy protein in the gels (WPI:SPI = 50:50) degraded faster than whey protein during gastric digestion. This study provided new information on the characteristics of composite protein emulsion gel fabricated with the WPI and SPI mixture.

Boosting emulsion properties: The role of β-sheet content and fibril length in soy protein isolate emulsions

This study aimed to research the effects of β-sheet content and fibril length in three categories ((low, medium, and high β-sheet) and (short, medium, and long fibrils)) on soy protein isolate (SPI) emulsions. The highest surface hydrophobicity (H0) (27,600 ± 100) was detected in the sample with the highest β-sheet content and the longest fibril length. The interfacial tension presented that the sample with the highest β-sheet content and longest fibril length could adsorb quickly at the oil (O)/water (W) interface. The emulsion stabilized by high β-sheet content and long fibril length had a lower droplet size (202 ± 4.35 nm) with more homogenous distribution and higher viscosity (8.75 ± 0.13 cP) due to more entanglement. According to the environmental stresses results (i.e., various ionic strengths (0–400 mM), pH changes (2–9.5), thermal treatment, and 30 days of storage), the emulsion prepared by the sample with the highest β-sheet content and the longest fibril length was more stable than other emulsions. Moreover, all emulsions were unstable against freeze-thaw treatment. Finally, it could be concluded that higher content of β-sheet and longer fibril led to the stability of emulsion through higher initial absorption at the O/W interface, formation of a continuous and thicker membrane coating at the O/W interfaces, viscosity improvement, and H0 enhancement.

Interaction between Chinese quince fruit proanthocyanidins and soy protein isolate: Effects on physical and oxidative stability of oil-in-water emulsions

Protein-based emulsions are extremely sensitive to droplet aggregation. The interaction between the proanthocyanidins (PAs) and protein can affect the efficacy of protein on the stability of emulsions. In this study, PAs with different molecular weights of ethyl acetate (EA) and retained aqueous (RA) phase were prepared from Chinese quince fruit and mixed with soy protein isolate (SPI) to form complexes, and their effects on the physical and oxidative stability of oil-in-water (O/W) emulsions were assessed. The results confirmed that SPI had fewer α-helices and more random coils when bound to EA and RA. The main forces between PAs and SPI were hydrogen bonds and hydrophobic interactions. Furthermore, RA-SPI, particularly EA-SPI, showed better foaming, emulsifying and antioxidant properties than SPI. The emulsifying activity index values of EA-SPI and RA-SPI were 39.7% and 33.4% higher than that of SPI, respectively. The physical and oxidative stability of O/W emulsions stabilized by SPI were lower than those stabilized by EA-SPI and RA-SPI. At day 15, the lipid hydroperoxide content of EA-SPI and RA-SPI emulsions was 30.5% and 10.3% lower than that of SPI emulsion, respectively. This study provides a basis for PAs as natural antioxidants to improve the stability of O/W emulsions.

Modulation of physicochemical properties of lipid droplets using soy protein isolate and lactoferrin interfacial coatings.

In order to improve the physicochemical stability of soy protein isolate (SPI) emulsion, lactoferrin (LF) was used to modify the interface layer. The stable multilayer emulsion can be formed when the content of lactoferrin is 0.5% at pH 5. The emulsion with good stability was at pH 3-7, and it was also stable to temperature change. The FFAs release of SPI emulsion and LF-SPI emulsion was 103.9% and 103.7%, respectively. The results showed that the lactoferrin layer did not hinder the digestion of oil and the bioaccessibility of carotenoids, but lactoferrin layer improved the physicochemical stability of SPI emulsions. This work provides information valuable in the design of emulsion formulations for applications in the food, pharmaceutical, and personal care industries.

The effect of subzero temperatures on the properties and structure of soy protein isolate emulsions

Different freezing temperatures (−5, −20, −40 and −80 ℃) could change soy protein isolate (SPI) structure and emulsion properties. After freezing at −5 ℃ and −20 ℃, the structure of the SPI loosened, the fluorescence intensity was red shifted, and the proportion of Phe, Tyr and Trp exposed increased. With decreasing temperature, the surface hydrophobicity (H0 × 100), the number of sulfhydryl groups and the number of disulfide bonds all rose, then fell (−40 ℃), and rose again (−80 ℃). The β-sheet content in the protein secondary structure increased from 32.71% (control) to 50.66% (−40 ℃) and then decreased to 37.05% (−80 ℃), while the β-turn and random coil contents showed the opposite pattern, which also confirmed aggregation. The emulsification performance of SPI after freezing treatment was decreased. The results of this study provide theoretical support for future production of frozen foods with added SPI.

Acid-Mediated Formation of Soybean Isolate Protein Emulsion Gels with Soybean Oil as an Active Component.

In this study, the effect of soybean oil concentration on the rheology, water-holding capacity, and thermal stability of acid-mediated soy protein isolate (SPI) emulsion gels was investigated. The microstructure was analyzed and interpreted by CLSM and SEM observations. The results showed that the addition of soybean oil improved the elastic properties of the acid-mediated SPI emulsion gels. The storage modulus increased from 330 Pa (2% soybean oil concentration) to 545 Pa (8% soybean oil concentration) with a significant increase (p < 0.05). The increase in soybean oil concentration resulted in more SPI-coated oil droplets acting as active particles, enhancing the gel network. The acid-mediated SPI emulsion gels became more disordered as the soybean oil concentration increased, with the fractal dimension increasing from 2.92 (2%) to 2.95 (8%). The rheological properties, thermal analysis, and microstructure of 6% SPI gel and acid-mediated SPI emulsion gels with 2% to 8% soybean oil concentration were compared. The acid-mediated SPI emulsion gels with soybean oil as the active filler showed improved gel properties, greater thermal stability, and a homogeneous network structure compared to the acid-mediated SPI emulsion gels.

Effects of pre-emulsion prepared using sucrose esters with different hydrophile-lipophile balances on characteristics of soy protein isolate emulsion films

The preparation of emulsion films using pre-emulsification has received extensive attention due to the enhancement of oil binding capacity. However, the different effects of water in oil (W/O) and oil in water (O/W) pre-emulsions on the physicochemical properties of films are still unclear. Therefore, the soy protein isolate (SPI) based emulsion films were prepared by W/O or O/W pre-emulsion using sucrose esters with different hydrophile-lipophile balances to investigate the properties of SPI emulsion (SPIE) films. The viscosity, storage moduli, and loss moduli of film-forming solutions (FFSs) with O/W pre-emulsion were higher than those of FFSs with W/O pre-emulsion. The oil droplets of FFSs with W/O pre-emulsion were large and uneven, and the oil droplet size increased after drying. Phase separation and macroporous network appeared in cross-sectional of SPIE films with W/O pre-emulsion according to scanning electron microscope images. Meanwhile, the SPIE films with W/O pre-emulsion demonstrated higher oil concentration and hydrophobicity on the upper surface compared with the SPIE films with O/W pre-emulsion. Low tensile strength, glass transition temperature, and high elongation at break and transparency value of SPIE films with O/W pre-emulsions were founded. The water vapor permeability of SPIE films with W/O pre-emulsion increased with the addition of oil, whereas the opposite trend appeared in that with O/W pre-emulsion. In conclusion, the structure and porosity of emulsion films could be affected by the pre-emulsion types, which can determine the application ranges.

Improving freeze-thaw stability and 3D printing performance of soy protein isolate emulsion gel inks by guar & xanthan gums

Frozen storage of 3D printing inks could increase their shelf life. We improved freeze-thaw stability and 3D printing performance of soy protein isolate (SPI) emulsion gel inks by guar (GG) and xanthan gums (XG). Freeze-thawed inks led to higher storage modulus (G′), lower water holding capability (WHC) and poor printing performance compared to initial inks. An increase in gums content decreased oil droplet aggregation and protein flocculation in all freeze-thawed inks, hence reducing syneresis in the gel structure and preventing solid-liquid separation during 3D printing. The freeze-thaw stability of SPI-XG inks was consistently greater than that of SPI-GG inks at the same concentrations, resulting in superior 3D printing performance. The hardness of cylinders printed with SPI-XG0.5 freeze-thawed inks was lower than that of the cylinders printed by initial inks, in contrast to the results of G'. At the maximum strain amplitude (500%), Lissajous analysis indicated that the SPI-XG0.5 freeze-thawed inks retained less energy than the initial inks, resulting in a weaker gel. Overall, this study demonstrated that freeze-thaw treatment negatively affected the 3D printing performance of SPI emulsion gel inks, but that the 3D printing performance of freeze-thaw inks could be reinforced by modifying the formulation.

Emulsifying properties and oil–water interface properties of succinylated soy protein isolate: Affected by conformational flexibility of the interfacial protein

This work aims to investigate the effect of succinylated modification of soy protein isolate (SPI) on its emulsifying and oil–water interfacial properties. The structure–effect mechanism was further analyzed between the emulsifying properties and the interfacial protein conformational flexibility of SPI. After succinylation, the ζ-potential of emulsion droplets increased, the particle size decreased, the turbidity and flocculation index decreased, and their macroscopic stability improved. The interfacial protein adsorption increased and the interfacial tension decreased, reaching their optimum when the degree of succinylation (DS) was 89.71%. As the increase of DS, the content of β-turn and random coil of interfacially adsorbed proteins increased to 16.27% and 25.15%, respectively, and the flexibility increased and the particle size decreased, while the opposite changes were observed for the unadsorbed proteins. Correlation analysis showed that the emulsifying and interfacial properties of SPI emulsions were closely related to the conformational flexibility of the interfacially adsorbed proteins, while the interfacial adsorption process was also affected by the ζ-potential and particle size of the unabsorbed proteins. This research could provide theoretical guidance on the regulation of protein-emulsifying properties by succinylation and reference data for the conformational characterization of interfacial proteins.

Development of soy protein isolate emulsion gels as extrusion-based 3D food printing inks: Effect of polysaccharides incorporation

Soy protein isolate (SPI) emulsion gel inks with polysaccharides of guar gum (GG) or xanthan gum (XG) for extrusion-based three-dimensional (3D) printing were investigated. The effects of the polysaccharide type and concentration on the printability, rheological properties, and microstructure of inks were discussed. Results indicated that the 3D printed products of SPI-GG0.5 inks demonstrated low dimensional printing deviation with great self-supporting capability and smooth and slightly flawed surface texture, while SPI-XG0.5 inks had the highest hardness and rough surface texture. The results of small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) test proved that SPI-XG0.5 inks exhibited the maximal gel strength, providing its 3D printed products with highest hardness. Secondary loops of Lissajous plots wouldn't emerge in SPI-XG0.5 inks, indicating decreased network flexibility and slightly larger dimensional printing deviation. The microstructure and fourier transform infrared (FTIR) analysis suggested the interaction of SPI with XG was stronger than that of GG due to hydrogen bonding and electrostatic interactions. When the XG concentration reached 0.5%, the network structure of the inks was changed, resulting in a rough surface texture of the 3D printed product. There are few studies on 3D printing of SPI emulsion gels, and this research offers more possibilities for the development of 3D printing inks.

Steam‐exploded camellia (Camellia oleifera Abel.) seed protein improves the stability of camellia seed oil emulsions

SummaryWe aimed here to investigate the ability of steam‐exploded camellia seed protein (SECSP) in stabilising steam‐exploded camellia seed oil‐in‐water emulsion in comparison with soy protein isolate (SPI). Emulsions with different SECSP and SPI contents (0.5, 1, 1.5 and 2 g 100 mL−1) were formulated and the effect of protein concentration on emulsion droplet size, zeta (ζ)‐potential, physical stability and bioaccessibility was examined. The stability of emulsion increased with increasing protein concentration. SECSP emulsion was characterised by smaller droplet sizes, higher surface charge and better stability than SPI emulsion. Furthermore, SECSP emulsion exhibited good digestive stability. SECSP emulsion showed creaming only at protein concentrations above 0.5 g 100 mL−1 after 28 days of storage, while SPI emulsion showed stratification and flocculation during the same storage period. Hence, steam explosion pretreatment physical modification of camellia seed protein (CSP) provides a novel approach of utilising proteins for emulsions stabilisation, and digestive stability improvement under gastrointestinal conditions.

Protease-induced soy protein isolate (SPI) characteristics and structure evolution on the oil–water interface of emulsion

The evolution of the microstructures and properties of soy protein isolate (SPI) at the oil–water interface under the induction of protease within 0.5 h and 2.0 h were analyzed by macroscopic characterization and structural analysis. There were significant differences in average particle size, zeta potential, microstructure, FT-IR, Raman and endogenous fluorescence of emulsion samples produced by different treatment times. Visual comparison showed the relatively uniform aggregation and distribution of SPI on the interface when induced for 1.0 h and characterized by zeta potential and rheology. Moreover, in FT-IR, Raman and intrinsic fluorescence spectra, it was found that with the induction of 0.5–2.0 h, the content of the β-turn structure was highest at 1.0 h, and strong fluorescence quenching occurred, which indicated that SPI at the interface was hydrolyzed into small peptides, and aggregated at 1.0 h and then hydrolyzed. What is more, no significant change in rheological properties was observed after induction for 1.5 h and 2.0 h. The results indicated that there existed –CO– and –NH binding due to electrostatic interaction and hydrogen bonding at 1.0 h, which caused the recombination of SPI molecules at the interface. The preparation process of SPI emulsion samples and the structural changes of SPI molecules in the oil-water interface under different protease induction times were investigated. • Evolution of structure and properties of SPI at oil–water interface protease treated. • SPI at the oil–water interface undergo aggregation and recombination after 1.0 h. • Longer treatment time reduces the viscosity and viscoelasticity of SPI emulsion. • Electrostatic interaction and hydrogen cause the aggregation and recombination of SPI.

Dynamic gastric stability and in vitro lipid digestion of soybean protein isolate and three storage protein-stabilized emulsions: Effects of ultrasonic treatment

The emulsification of vegetable protein is closely related to solubility. The purpose of this study was to evaluate the effect of ultrasound on protein emulsification and to provide a prospective method for assessing the digestive properties of emulsions. In this article, we investigate the emulsion stability of ultrasonic pretreated soy protein isolate (SPI), and its three storage proteins, namely β-conglycinin (7S), lipophilic protein (LP), and glycinin (11S), under dynamic gastric conditions. The effects of these emulsions on lipolysis during digestion in the small intestine are also assessed using an in vitro dynamic human stomach simulator and a small intestine model. Particle size and ζ-potential measurements, as well as confocal laser scanning microscopy, revealed that during dynamic gastric digestion, the flocculation degree and floc size of 7S and soybean LP emulsions are larger than that of 11S and SPI emulsions. Meanwhile, ultrasound pretreatment of the proteins was found to prevent the agglomeration of the emulsion in a dynamic gastric environment. Moreover, enhanced flocculation delayed oil droplet delivery to the small intestine and subsequently retarded the release of lipophilic nutrients. The droplet size, molecular weight, and protein secondary structures of the ultrasonicated proteins were conducive to relatively higher rates and degrees of lipolysis in intestinal digestion than those of unsonicated proteins. Additionally, the slow-release effect of LP was superior to that of 11S and SPI, whereas 7S was comparatively more difficult to digest. The present study elucidated the fate of soy protein in the digestive tract and may facilitate microstructural food design to regulate physiological responses during digestion.