Emulsifying properties of sweet potato protein: Effect of protein concentration and oil volume fraction

The effect of protein concentrations (0.1, 0.25, 0.5, 1.0, 1.5 and 2.0% w/v) and oil volume fractions (5, 15, 25, 35 and 45% v/v) on properties of stabilized emulsions of sweet potato proteins (SPPs) were investigated by use of the emulsifying activity index (EAI), emulsifying stability index (ESI), droplet size, rheological properties, interfacial properties and optical microscopy measurements at neutral pH. The protein concentration or oil volume fraction significantly affected droplet size, interfacial protein concentration, emulsion apparent viscosity, EAI and ESI. Increasing of protein concentration greatly decreased droplet size, EAI and apparent viscosity of SPP emulsions; however, there was a pronounced increase in ESI and interfacial protein concentration (P < 0.05). In contrast, increasing of oil volume fraction greatly increased droplet size, EAI and emulsion apparent viscosity of SPP emulsions, but decreased ESI and interfacial protein concentration significantly (P < 0.05). The rheological curve suggested that SPP emulsions were shear-thinning non-Newtonian fluids. Optical microscopy clearly demonstrated that droplet aggregates were formed at a lower protein concentration of <0.5% (w/v) due to low interfacial protein concentration, while at higher oil volume fractions of >25% (v/v) there was obvious coalescence. In addition, the main components of adsorbed SPP at the oil–water interface were Sporamin A, Sporamin B and some high-molecular-weight aggregates formed by disulfide linkage.     

Emulsifying properties of canola and flaxseed protein isolates produced by isoelectric precipitation and salt extraction

The emulsifying (emulsion capacity, EC; emulsion activity/stability indices, EAI–ESI and creaming stability, CS) and physicochemical properties (surface charge/hydrophobicity, protein solubility, interfacial tension, and droplet size) of chickpea (ChPI), faba bean (FbPI), lentil (LPI), and pea (PPI) protein isolates produced by isoelectric precipitation and salt extraction were investigated relative to each other and a soy protein isolate (SPI). Both the legume source and method of isolate production showed significant effects on the emulsifying and physicochemical properties of the proteins tested. All legume proteins carried a net negative charge at neutral pH, and had surface hydrophobicity values ranging between 53.0 and 84.8 (H₀-ANS), with PPI showing the highest value. Isoelectric precipitation resulted in isolates with higher surface charge and solubility compared to those produced via salt extraction. The EC values ranged between 476 and 542 g oil/g protein with LPI showing the highest capacity. Isoelectric-precipitated ChPI and LPI had relatively high surface charges (~−22.3 mV) and formed emulsions with smaller droplet sizes (~ 1.6 μm), they also displayed high EAI (~ 46.2 m²/g), ESI (~ 84.9 min) and CS (98.6%) results, which were comparable to the SPI.     

Emulsifying characteristics of commercial canola protein–hydrocolloid systems

Emulsifying properties of commercial canola protein isolate (CPI)–hydrocolloid-stabilized emulsions were evaluated under varied conditions (CPI, salt and hydrocolloid concentrations; pH, denaturants). Emulsifying activity index (EAI) and emulsion stability (ES) were determined by turbidimetric testing. The results showed that under complexing conditions (at pH 6), the addition of 1% (w/v) κ-carrageenan (κ-CAR) increased the EAI of CPI-stabilized emulsions from 162 to 201 m²/g and ES from 68% to 95%. Under conditions promoting incompatibility (at pH 10), the use of 1% (w/v) guar gum increased the EAI of CPI-stabilized emulsions from 68 to 177 m²/g and ES from 66% to 100%. The lower EAI and ES values observed in CPI–hydrocolloid-stabilized emulsions treated with sodium salts and denaturants support the involvement of hydrophobic interactions, hydrogen bonds and disulfide linkages in the emulsification of these systems. Interfacial properties of CPI–hydrocolloid mixtures were improved by electrostatic complexing and incompatibility, making these systems suitable for stabilizing food emulsions.     

Emulsifying properties of soy protein isolates obtained by microfiltration

Soy protein isolate (SPI) fractions were produced using two different pore size microfiltration membranes. Microfiltration was carried out on SPI produced by isoelectric precipitation of a crude protein extract. Five fractions were obtained: two retentates and two permeates from the two membranes plus an intermediate fraction obtained as the retentate on the small‐pore‐size membrane using the permeate from the larger‐pore‐size membrane. Emulsions stabilised by the retentate fractions exhibited higher values (P < 0.01) of emulsion stability index (ESI) and emulsifying activity index (EAI) than those stabilised with fractions made from the permeates. The intermediate fraction gave intermediate ESI values, while the EAI values were not significantly different from those for SPI and one of the retentates. SDS‐PAGE profiles indicated that the fractions exhibiting high functionality in terms of ESI and EAI were also richer in 7S globulin soy protein subunits. © 2002 Society of Chemical Industry     

High pressure versus heat treatments for pasteurisation and sterilisation of model emulsions

Heat treatments can have considerable influence on the droplet size distribution of oil-in-water emulsions. In the present study, high-pressure (HP) pasteurisation and sterilisation were evaluated as alternatives for heat preservation of emulsions. HP conditions used were 600 MPa, 5 min, room temperature and 800 MPa, 5 min, 80 °C initial temperature, 115 °C maximum temperature for HP pasteurisation and HP sterilisation respectively. The effects on droplet size of these conditions were compared to heat treatments for whey protein isolate (WPI) and soy protein isolate (SPI) emulsions at two pH values and two ionic strengths. For WPI, also the effect of protein in the bulk phase was evaluated.Both HP and heat pasteurisation treatments resulted in similar or slightly decreased average droplet sizes compared to the untreated samples. For neutral SPI emulsions, heat sterilisation increased the average droplet size from 1.6 μm to 43.7 μm, while HP sterilisation resulted only in a small increase towards an average droplet size of 2.1 μm. The neutral WPI emulsions, except those with a high ionic strength, gave similar results with respect to the droplet size, showing that for neutral pH WPI or SPI emulsions HP sterilisation is preferable above heat sterilisation. Concerning the low pH WPI emulsions, the droplet sizes were unaffected after both heat and HP sterilisation.Industrial relevanceHeat pasteurisation and sterilisation are effective treatments to preserve food products that are based on emulsions with respect to microbial safety. However, heat treatments can negatively affect emulsion stability. Currently, in addition to high pressure at room temperature, high-pressure treatments at elevated temperature received a great deal of interest to achieve sterilised products. This study evaluated the effects of both heat and high-pressure pasteurisation and sterilisation on droplet size of whey protein isolate and soy protein isolate emulsions. It was shown that for pasteurisation treatments, both heat and high pressure have minor effects on the droplet size of the emulsion. However, for sterilisation purposes high-pressure treatment is preferable for emulsion at neutral pH. High-pressure sterilisation can therefore be interesting alternatives to heat treatments to preserve emulsion stability.     

Temperature and pH as factors influencing droplet size distribution and linear viscoelasticity of O/W emulsions stabilised by soy and gluten proteins

The influence of pH and two post-emulsification treatments (pH modification and thermal cycles) over linear dynamic viscoelasticity and droplet size distribution, DSD, of O/W emulsions (75% oil) stabilized either by soy protein isolate, SPI, or wheat gluten, WG were studied in the present work. Rheological properties and droplet size of fresh emulsions showed an important dependence on pH as a consequence of the role of electrostatic interactions, not being possible to obtain a stable emulsion for pH values close to the protein isoelectric point, pI, (4–5 for SPI and 6 for WG). In order to overcome this inconvenient, an alternative emulsification procedure, basically consisting in a modification of pH after emulsification (indirect emulsification), was successfully developed. Emulsions obtained after this post-emulsification treatment, showed higher elastic (G′) and loss (G″) moduli and also larger oil droplets than fresh emulsions prepared at the same pH. Moreover, the application of upward/downward temperature cycles from 20 to 70 °C to emulsions directly prepared at a pH yielded to significantly higher values of the rheological functions when compared to those found for fresh emulsions. Accordingly, both post-emulsification treatments lead to apparent enhancements in emulsion rheology and microstructure, which is indicative of a good potential to improve long-term emulsion stability.     

Emulsion properties of algae soluble protein isolate from Tetraselmis sp.

To study possible applications of microalgae proteins in foods, a colourless, protein-rich fraction was isolated from Tetraselmis sp. In the present study the emulsion properties of this algae soluble protein isolate (ASPI) were investigated. Droplet size and droplet aggregation of ASPI stabilized oil-in-water emulsions were studied as function of isolate concentration (1.25–10.00 mg/mL), pH (3–7), and ionic strength (NaCl 10–500 mM; CaCl₂ 0–50 mM). Whey protein isolate (WPI) and gum arabic (GA) were used as reference emulsifiers. The lowest isolate concentrations needed to reach d₃₂ ≤ 1 μm in 30% oil-in-water emulsions were comparable for ASPI (6 mg/mL) and WPI (4 mg/mL). In contrast to WPI stabilized emulsions ASPI stabilized emulsions were stable around pH 5 at low ionic strength (I = 10 mM). Flocculation only occurred around pH 3, the pH with the smallest net droplet ζ-potential. Due to the charge contribution of the anionic polysaccharide fraction present in ASPI its droplet ζ-potential remained negative over the whole pH range investigated. An increase in ionic strength (≥100 mM) led to a broadening of the pH range over which the ASPI stabilized emulsions were unstable. GA emulsions are not prone to droplet aggregation upon changes in pH or ionic strength, but much higher concentrations are needed to produce stable emulsions. Since ASPI allows the formation of stable emulsions in the pH range 5–7 at low protein concentrations, it can offer an efficient natural alternative to existing protein–polysaccharide complexes.     

植物球蛋白/姜黄素纳米复合物的制备及其对O/W型Pickering乳液氧化稳定性影响

本论文以两类植物球蛋白:豌豆分离蛋白(PPI)和大豆分离蛋白(SPI)为材料制备荷载姜黄素蛋白纳米复合物,并探究荷载前后蛋白所制备乳液的物理和氧化稳定性差异。结果表明:PPI和SPI在pH 3.0和pH 7.0下荷载前后蛋白纳米颗粒粒径没有明显变化。pH 7.0时两蛋白姜黄素荷载量均高于pH 3.0,各pH下SPI荷载量要高于PPI。表面疏水性的显著降低与荧光淬灭现象发生表明形成两种蛋白纳米复合物的主要作用力为疏水相互作用,同时在两pH下,PPI比SPI荧光蓝移趋势更明显且有效淬灭常数也更大,即更易形成复合物。与原蛋白相比,荷载后各蛋白颗粒所制备乳液乳化活性有少许降低,同时pH 3.0时各蛋白颗粒乳化活性要高于pH 7.0。各乳液生成初级氧化产物脂质氢过氧化物浓度的变化趋势与生成次级氧化产物TBARS相类似,均为荷载姜黄素后各乳液氧化水平加速,同时pH 3.0时各类型乳液油滴氧化程度均高于pH 7.0。     

Interfacial and emulsifying properties of lentil protein isolate

The dynamic interfacial tension (DIFT) at oil–water interface, diffusion coefficients, surface hydrophobicity, zeta potential and emulsifying properties, including emulsion activity index (EAI), emulsion stability index (ESI) and droplet size of lentil protein isolate (LPI), were measured at different pH and LPI concentration, in order to elucidate its emulsifying behaviour. Sodium caseinate (NaCas), whey protein isolate (WPI), bovine serum albumin (BSA) and lysozyme (Lys) were used as benchmark proteins and their emulsifying property was compared with that of LPI. The speed of diffusion-controlled migration of these proteins to the oil/water interface, was in the following order: NaCas > LPI > WPI > BSA > Lys, while their surface hydrophobicity was in the following order: BSA > LPI > NaCas > WPI > Lys. The EAI of emulsions stabilised by the above proteins ranged from 90.3 to 123.3 m²/g and it was 93.3 ± 0.2 m²/g in LPI-stabilised emulsion. However, the stability of LPI-stabilised emulsions was slightly lower compared to that of WPI and NaCas-stabilised emulsions at the same protein concentration at pH 7.0. The ESI of LPI emulsions improved substantially with decrease in droplet size when protein concentration was increased (20–30 mg/ml). Reduction of disulphide bonds enhanced both the EAI and ESI compared to untreated samples. Heat treatment of LPI dispersions resulted in poor emulsion stability due to molecular aggregation. The stability of LPI-stabilised emulsions was found to decrease in the presence of NaCl. This study showed that LPI can be as effective emulsifiers of oil-in-water emulsions as are WPI and NaCas at ?20 mg/ml concentrations both at low and neutral pH. The emulsifying property of LPI can be improved by reducing the intra and inter-disulphide bond by using appropriate reducing agents.     

Emulsions stabilized by heat-treated collagen fibers

The emulsifying properties of collagen fiber were modified by heat treatment at temperatures ranging from 50 to 85 °C for 20 or 60 min. In addition to heat treatment, the influence of pH (3.5 and 9.2) and the emulsifying process (rotor-stator device and high-pressure homogenizer) were evaluated on oil-in-water emulsions stabilized by collagen fiber through visual analysis (stability), microstructure and rheological measurements. Emulsions homogenized using solely the rotor-stator device showed phase separation and a larger mean droplet size (d₃₂), except for the emulsion composed by non-heated collagen fiber. The alkaline emulsions showed lower kinetic stability, since collagen fibers have a lower net charge (zeta potential) at higher pH values, decreasing the electrostatic stability process. Heat treatment slightly decreased the protein charge and significantly reduced the insoluble protein content, suggesting a decrease in the emulsifying properties of the collagen fiber. The use of high-pressure homogenization (20-100 MPa) made it possible to produce acid emulsions with a reduced droplet size and distribution. At 20 MPa, the emulsions showed a higher d₃₂ value (between 3.17 and 1.18 μm), while at 60 and 100 MPa the emulsions presented lower d₃₂ values (between 0.74 and 0.94 μm) without any significant variation between the different heat-treated collagen fibers, but showing a noticeable decrease in emulsion viscosity and elasticity with increases in the homogenization pressure and heat treatment.     

Influence of enzymatic hydrolysis,pH and storage temperature on the emulsifying properties of canola protein isolate and hydrolysates

The aim of this work was to enhance emulsification properties of canola proteins through enzymatic proteolysis and pH variaton. Canola protein isolate (CPI) and hydrolysates (CPHs) were used to form emulsions at pH 4.0, 7.0 and 9.0 followed by storage at 4 or 25 °C for 7 days. Controlled enzymatic hydrolysis led to increased peptide bond cleavage with time (0.23 g/100 g in CPI to 7.18 g/100 g after 24‐h Alcalase hydrolysis). Generally, oil droplet sizes were smaller for emulsions made at pH 9.0, which suggest better quality than those made at pH 4.0 and 7.0. Trypsin hydrolysate emulsions were the most physically stable at pH 7.0 and 9.0; in contrast, the pepsin hydrolysate emulsions were unstable at all conditions. The results suggest that selective enzymatic hydrolysis could play an important role in enhancing successful incorporation of canola proteins and peptides into food systems as protein emulsifiers.     

Emulsifying properties of chickpea protein isolates: Influence of pH and NaCl

Structure and emulsifying properties of chickpea protein isolates (CPI) as a function of protein concentration, oil volume, pH and ionic strength were studied. The optimum protein concentration 2 g l⁻¹ used to determine the emulsifying properties was obtained. Emulsifying activity index (EAI) increased from 244 to 376 m² g⁻¹ with pH from 3.0 to 11.0 except the protein isoelectric point (pI 5.0), where the EAI was 20 m² g⁻¹ and emulsion droplet size was the largest. At lower ionic strengths (0.0–0.1 M NaCl, pH 7.0), EAI decreased from 253 to 72.4 m² g⁻¹; however, it increased from 72.4 to 231.4 m² g⁻¹ at higher ionic strengths (0.1–1.0 M NaCl). A positive relation between EAI and surface hydrophobicity (S₀) of CPI at various ionic strengths was obtained, while EAI was independent of S₀ under different pH values. α-Helix was the major configuration of CPI at the pI or lower ionic strength.     

Formation and Coalescence Stability of Emulsions Stabilized by Different Milk Proteins

The volume fraction of oil emulsified, surface area, droplet diameter, and coalescence rates of emulsions stabilized by different milk proteins were studied at protein concentrations of 0.25, 0.5, 1.0, and 2.0% (w/w); pH 4, 5, and 7; and ionic strengths 0.1 and 0.2. The emulsion activity index (EAI) and coalescence stability generally increased with increasing protein solubility and hydrophobicity. The volume fraction of oil emulsified decreased with increasing ionic strength. Coalescence stability correlated with droplet diameter for emulsions stabilized by α-lactalbumin, β-lactoglobulin, and sodium caseinate (r²=0.96). With the exception of β-lactoglobulin-stabilized emulsions, coalescence stability was largely unaffected by pH.     

Gelling properties of protein fractions and protein isolate extracted from Australian canola meal

Gelling properties of canola albumin and globulin fractions, and canola protein isolate (CPI) were examined in this study. The effects of pH and salt concentration on canola protein gelling properties were studied primarily by means of dynamic oscillatory rheology and gel texture analysis. The findings were supported by confocal laser scanning microscopy (CLSM) images of the gels, isoelectric point, and solubility measurement data. All canola proteins showed typical heat-set gel protein profiles. Gels formed at higher pH had better gelling properties including higher overall resistance to deformation (G*), higher gel elasticity (low tan δ ), higher fracture stress and firmness, and denser gel microstructure. Isoelectric points of canola proteins used in this study were in the range of pH 3.0–4.7 where low protein solubility was observed. The albumin fraction was able to form a very weak gel at pH 4, whereas the globulin fraction and CPI precipitated due to loss of protein surface charge. The effects of NaCl on gelling were protein sample dependent. The presence of NaCl negatively affected gelling properties of albumin and globulin fractions, with decreases in overall resistance to deformation (G*), and fracture stress and firmness, but positively affected CPI gels in the same aspects. The elasticity (tan δ) of all canola protein gels remained constant in the presence of NaCl. Frequency sweep analysis revealed that the albumin fraction and CPI formed weak gels, whereas the globulin fraction formed a strong gel. Strain sweep analysis further confirmed that the globulin fraction formed a stronger gel with a critical strain of at least 10%. This study demonstrates the high potential of canola proteins, particularly the globulin fraction, as a prospective gelling agent.     

Cross-linking proteins by laccase: Effects on the droplet size and rheology of emulsions stabilized by sodium caseinate

The aim of this work was to evaluate the influence of laccase and ferulic acid on the characteristics of oil-in-water emulsions stabilized by sodium caseinate at different pH (3, 5 and 7). Emulsions were prepared by high pressure homogenization of soybean oil with sodium caseinate solution containing varied concentrations of laccase (0, 1 and 5 mg/mL) and ferulic acid (5 and 10 mM). Laccase treatment and pH exerted a strong influence on the properties with a consequent effect on stability, structure and rheology of emulsions stabilized by Na-caseinate. At pH 7, O/W emulsions were kinetically stable due to the negative protein charge which enabled electrostatic repulsion between oil droplets resulting in an emulsion with small droplet size, low viscosity, pseudoplasticity and viscoelastic properties. The laccase treatment led to emulsions showing shear-thinning behavior as a result of a more structured system. O/W emulsions at pH 5 and 3 showed phase separation due to the proximity to protein pI, but the laccase treatment improved their stability of emulsions especially at pH 3. At pH 3, the addition of ferulic acid and laccase produced emulsions with larger droplet size but with narrower droplet size distribution, increased viscosity, pseudoplasticity and viscoelastic properties (gel-like behavior). Comparing laccase treatments, the combined addition of laccase and ferulic acid generally produced emulsions with lower stability (pH 5), larger droplet size (pH 3, 5 and 7) and higher pseudoplasticity (pH 5 and 7) than emulsion with only ferulic acid. The results suggested that the cross-linking of proteins by laccase and ferulic acid improved protein emulsifying properties by changing functional mechanisms of the protein on emulsion structure and rheology, showing that sodium caseinate can be successfully used in acid products when treated with laccase.     

Ability of flaxseed and soybean protein concentrates to stabilize oil-in-water emulsions

The ability of flaxseed protein concentrate (FPC) to stabilize soybean oil-in-water emulsion was compared with that of soybean protein concentrate (SPC). The stability of emulsions increased with increase in protein concentration. The FPC-stabilized emulsions had smaller droplet size and higher surface charge, but worse stability at the same protein concentration compared to SPC-stabilized emulsions. Oil-in-water emulsions stabilized by both proteins were diluted and compared at different pH values (3–7), ionic strength (0–200 mM NaCl) and thermal treatment regimes (25–95 °C for 20 min). Considerable emulsion droplet flocculation occurred around iso-electric point of both proteins: FPC (pH 4.2) and SPC (pH 4.5). FPC and SPC-stabilized emulsions remained relatively stable against droplet aggregation and creaming at NaCl concentration below 100 and 50 mM, respectively. The emulsions stabilized by both proteins were fairly stable within these thermal processing regimes. FPC appears to be less effective as an emulsifier compared to SPC due to its lower emulsion viscosity. Hence, FPC could be more effective in emulsions that are fairly viscous.     

Improvement in emulsifying properties of soy protein isolate by conjugation with maltodextrin using high‐temperature,short‐time dry‐heating Maillard reaction

Soy protein isolate (SPI)–maltodextrin (MD) conjugates were synthesised using Maillard reaction under high‐temperature (90, 115 and 140 °C), short‐time (2 h) dry‐heating conditions. The loss of free amino groups in proteins and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) profile confirmed that SPI‐MD conjugates were formed and higher dry‐heated temperatures could increase the glycosylation degree. The emulsifying properties of SPI and SPI‐MD conjugates were evaluated in oil‐in‐water emulsions. The emulsions stabilised with SPI‐MD conjugates synthesised at 140 °C exhibited higher emulsifying stability and excellent storage stability against pH, ionic strength and thermal treatment compared with those synthesised at 90 °C, 115 °C and SPI stabilised emulsions. This might be due to a greater proportion of conjugated MD in SPI‐MD conjugates synthesised at 140 °C because of the higher glycosylation degree, and more conjugated MD on the droplet surface could provide steric effect and enhance the stability of the droplets in the emulsions.     

Emulsifying characterization of hens egg yolk proteins in oil-in-water emulsions

Emulsifying properties of egg yolk as a function of pH and oil volume were studied. Egg yolk proteins formed larger emulsion particles at pH 3 and the mean droplet size of the emulsions was decreased with increasing pH. A linear relationship between turbidity and mean droplet size of egg yolk emulsions could not be obtained. This may be due to the floculation of the emulsions. Egg yolk proteins formed thicker multilayers at low oil volume, however total protein adsorption ratio against original proteins was 55–65%, independent to protein and oil concentration. Electrophoretic analysis of the egg yolk emulsion revealed that the main components to adsorb at the interface was glanular lipovitellins, even though its emulsifying property was lower than that of plasma because of poor solubility at low ionic strength (0.1 M NaCl) at pH 7. These results indicate that the main contributor for egg yolk emulsion is granules and it can affect the emulsifying properties of egg yolk at different pH values.     

Manipulating interfacial behaviour and emulsifying properties of myofibrillar proteins by L-Arginine at low and high salt concentration

The present work examined the impact of L-Arginine (Arg) on the emulsifying properties, interfacial behaviour and conformational characteristics of myofibrillar proteins (MPs) at high (0.6 m ) and low (0.15 m ) salt concentration to maintain good emulsifying properties of MPs at low salt concentration. The data indicated that Arg increased the emulsifying activity index/emulsion stability index (EAI/ESI) and decreased the CI and droplet size of emulsions regardless of salt concentration. Raman spectra revealed that the α-helix content decreased from 60.30% to 51.26% at high salt concentration, and from 60.20% to 54.82% at low salt concentration in the presence of Arg. In addition, MPs treated with Arg exhibited a higher interfacial pressure and more rapidly diffusion to the oil surface. Meanwhile, Arg increased the interfacial protein loading. The results demonstrated that Arg caused the unfolding of MPs, promoting the adsorption of proteins and decreasing the interfacial tension, ultimately improving the stability of emulsions at low salt concentration.     

Surface Properties of Heat‐Induced Soluble Soy Protein Aggregates of Different Molecular Masses

Suspensions (2% and 5%, w/v) of soy protein isolate (SPI) were heated at 80, 90, or 100 °C for different time periods to produce soluble aggregates of different molecular sizes to investigate the relationship between particle size and surface properties (emulsions and foams). Soluble aggregates generated in these model systems were characterized by gel permeation chromatography and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. Heat treatment increased surface hydrophobicity, induced SPI aggregation via hydrophobic interaction and disulfide bonds, and formed soluble aggregates of different sizes. Heating of 5% SPI always promoted large‐size aggregate (LA; >1000 kDa) formation irrespective of temperature, whereas the aggregate size distribution in 2% SPI was temperature dependent: the LA fraction progressively rose with temperature (80→90→100 °C), corresponding to the attenuation of medium‐size aggregates (MA; 670 to 1000 kDa) initially abundant at 80 °C. Heated SPI with abundant LA (>50%) promoted foam stability. LA also exhibited excellent emulsifying activity and stabilized emulsions by promoting the formation of small oil droplets covered with a thick interfacial protein layer. However, despite a similar influence on emulsion stability, MA enhanced foaming capacity but were less capable of stabilizing emulsions than LA. The functionality variation between heated SPI samples is clearly related to the distribution of aggregates that differ in molecular size and surface activity. The findings may encourage further research to develop functional SPI aggregates for various commercial applications.