Comparison of Interfacial and Foaming Properties of Soy and Whey Protein Isolates (2025)

Comparative study of foaming properties of whey and isolate soybean proteins

Food Research International, 2002

Whey soy proteins (WSP) is obtained from the soluble fraction separated in the isoelectric precipitation of the major components of native soy isolate (NSI), the 7S and 11S fractions. WSP is composed mainly by Kunitz Trypsin Inhibitor and Lectin. Water solubility of WSP was less affected by pH than that of NSI. Therefore, WSP has good foaming capacity in all pH range (pH 2-10). According to the rate of liquid incorporation into the foam, WSPs have higher tensioctive behavior, and in consequence, they are rapidly adsorbed into the water-air interface. At extreme pHs, with low or high ionic strength, good foams were obtained with WSP and NSI. Mixtures of both in different relations, showed better stabilization and foam formation than that expected for the simple additivity of both preparations. This effect was more evident at high ionic strength. These results indicate that there is a synergistic effect between these proteins in relation to foaming properties.

Rheological Method for Kinetics of Drainage and Disproportionation of Soy Proteins Foams

Journal of Food Science, 1997

The effect of soy protein (SP) concentration and denaturation on foaming properties was investigated. To measure drainage and disproportionation rates, a special method was based on measurements of time dependency of foam viscosity. Foam expansion reached a maximum at 3% protein concentration for denatured and 5% for native SP. Rates of drainage and disproportionation were greatly decreased by increasing protein concentration due to increased liquid viscosity (drainage) and to lowering of surface tension (disproportionation). Denaturation of SP increased foam expansion and decreased rate of drainage over the concentration range but lowered rate of disproportionation at > 4% protein.

Effects of high ultrasound intensity on foam stability and interfacial relationship of soluble soy protein isolate

The objective was to determine the effect of ultrasound (HIUS) on the stability of foams and interfacial properties at equilibrium conditions at pH 7 and 3 of soluble fraction of soy protein isolate (SSPI). The samples were sonicated for 20 min using an ultrasonic processor Vibra Cell Sonics. The foams were produced using a foaming commercial instrument FoamScan. Foam formation and stability were measured by conductimetric and optical methods. Moreover, the evolution of the bubble size change in the foam was determined by a second CCD camera. Measurements of the variations of surface pressure (π) with the molecular area (A) of films were analyzed at the air-water interface with an automated KSV Langmuir mini-trough. In spite of the better foam obtained after HIUS, trough the relative foam conductance Cf%, the stabilizing parameters in the foam: half-life time t½, relaxation times corresponding to the kinetics of liquid: td and tdc depended of pH studied which would be relating with ...

Rheology and thermal transitions of enzymatically modified soy protein and polysaccharides mixtures, of potential use as foaming agent determined by response surface methodology

Food Bioscience, 2013

The complex mixture we studied could be used as a foaming agent under refrigeration or heating conditions because of the presence of one polysaccharide that gels on heating, a hydroxypropylmethylcellulose called E4M, and another that gels on cooling, κ-carrageenan (κC), together with hydrolyzed soy protein. The concentration effect of each biopolymer on its rheological behavior at 70 1C and thermal behavior of the mixture was studied. For this purpose, a Doehlert design and a response surface methodology were used to design the experiment and analyze it respectively. The rheology of mixed systems on heating was mainly determined by E4M because this polysaccharide gels on heating. However, a high protein or κC concentration E4M gelation was prevented. The statistical analysis showed that E4M exhibited the best performance for both the variables studied.

Role of Polysaccharides in Complex Mixtures with Soy Protein Hydrolysate on Foaming Properties Studied by Response Surface Methodology

International Journal of Carbohydrate Chemistry, 2014

The complex mixture studied, a hydrolyzed soy protein (HSP), κ-carrageenan (κC), and an hydroxypropyl methylcellulose (HPMC), could be used as a foaming agent under refrigeration or heating conditions because of the presence of one polysaccharide (HPMC) that gels on heating and another (κC) that gels on cooling. The objective of this work was to study the role of these polysaccharides on foaming properties by whipping methods at heating conditions. For this purpose, response surface methodology was used to optimize the mixed product in foamed food systems. The obtained results showed that the combination of E4M, κC, and HSP is an adequate strategy to generate good foam capacity and stability at heating conditions. The huge stability increase of foams at heating conditions was ascribed to combined effect of polysaccharides: gelling property of E4M and the viscozieng character imparted by κC to continuous phase of foaming.

Effect of dynamic high-pressure treatment on the interfacial and foaming properties of soy protein isolate–hydroxypropylmethylcelluloses systems

Food Hydrocolloids, 2011

The objective of the work was to study the effect of dynamic high-pressure homogenization (HPH) on the interfacial and foaming properties of soy protein isolate (SP) and surface-active polysaccharides (E4M and E15) with different molecular weight. SP was dispersed with water (2% w/v) together with the polysaccharides (0.3% w/v) and subjected to high-pressure from 0 to 300 MPa, in 100 MPa intervals. After treatment, foam overrun by whipping method, viscosity, particle size distribution and surface pressure at 48 s of drop formation time, of systems were measured. The effect of HPH of these systems on foam overrun was not directly relation with the effect on the surface pressure at short adsorption time. The viscosity decrease may be explained some of the foaming results together with interfacial performance at longer adsorption time than 48 s which depend on the system and level of pressure applied. According to the polysaccharide used in this work, interactions between SP and polysaccharides apparently favour the foam overrun on untreated mixed systems; this effect was promoted using HPH particularly in the case of E15 at 300 MPa. The effect of SPeE4M was less pronounced from the one observed for E15. Thus, the molecular weight of polysaccharides is a very important factor of interaction with soy protein isolate under these conditions of high-pressure homogenization.

Effect of dynamic heat treatment on the physical properties of whey protein foams

Food Hydrocolloids, 2009

The influence of dynamically heat-induced aggregates on whey protein foams was investigated as a function of the thermal treatment applied with the aim of determining the optimal temperature for the production of heat-induced aggregates dedicated to foaming. The native protein solutions (2% w/v WPI; 50 mM NaCl) at neutral pH were heat-treated using a tubular heat exchanger between 70 C and 100 C. Protein denaturation and aggregation were followed by micro-differential scanning calorimetry, size exclusion chromatography, laser diffraction and dynamic light scattering. The protein solutions were whipped using a kitchen mixer to produce foams. Foam overrun, stability against drainage, texture and bubble size distribution were measured. Experimental results showed that overrun slightly decreased with an increase of the temperature used to treat proteins, whereas foam rigidity was improved at the same time. An optimal temperature of thermal treatment was found at 80 C for stability against drainage. Quantitative analyses showed that the formation of approximately 10% soluble aggregates in the WPI sample before whipping maintained a good level of overrun, lead to an increased stability against drainage and to an improved rigidity for whey protein foams. Conversely, they revealed that an increase of temperature above 80 C before foaming did not improve anymore the functional properties of the proteins.

Factors determining the physical properties of protein foams

Food Hydrocolloids, 2006

Protein foams are an integral component of many foods such as meringue, nougat and angel food cake. With all these applications, the protein foam must first obtain the desired level of air phase volume (foamability), and then maintain stability when subjected to a variety of processes including mixing, cutting and heating. Therefore, factors determining foamability and stability to mechanical and thermal processing are important to proper food applications of protein foams. We have investigated the effects of protein type, protein modification and co-solutes on overrun, stability and yield stress. The level of overrun generated by different proteins was: whey protein isolate hydrolysates Owhey protein isolateZb-lactoglobulinZegg whiteOa-lactalbumin. The level of yield stress generated by different proteins was: egg whiteOwhey protein isolate hydrolysatesRb-lactoglobulinOwhey protein isolateOa-lactalbumin. Factors that decreased surface charge (pHwpI or high ionic strength) caused a more rapid adsorption of protein at the air-water interface, generally increased dilatational viscoelasticity and increased foam yield stress. The elastic component of the dilatational modulus of the air-water interface was correlated with foam yield stress. The properties of foams did not predict performance in making angel food cakes. A model for foam performance in angel food cakes is proposed. q (E.A. Foegeding).

Fibrillization of whey proteins improves foaming capacity and foam stability at low protein concentrations

Journal of Food Engineering, 2014

The foaming properties of fibrillar whey proteins were compared with those of native or denatured whey proteins and also with egg white protein. Whey protein foaming capacity and stability were related to protein concentration, pH, time of whipping, pressure and heating treatments. Foams produced from fibrils showed significant improvement in foaming capacity and stability when compared with non-fibrillar whey proteins. Dynamic high shear (microfluidization) or moderate shear (Ultra-Turrax mixing) of fibrillar protein dispersions did not significantly affect their subsequent foaming properties. Furthermore, foams prepared with fibrillar whey protein (63% protein) had comparable capacity and stability to that from egg white protein, which is the traditional foaming ingredient in food industry. Results suggest that fibrillized whey proteins are highly effective foaming agents even at relatively low protein concentrations (1-3% w/w).

Physico-chemical factors controlling the foamability and foam stability of milk proteins: Sodium caseinate and whey protein concentrates

We explored the foaming behavior of the two main types of milk proteins: flexible caseins and globular whey proteins. Direct foam comparison was complemented with measurements in model experiments such as thin foam films, dynamic surface tension, and protein adsorption. Foaming was studied as a function of pH (from below to above isoelectric point, pI) and range of ionic strengths. Maximum foamability was observed near pI z 4.2 for WPC in contrast to sodium caseinate which had minimum foaming near pI ¼ 4.6. Good foamability behavior correlated well with an increased adsorption, faster dynamic surface tension decrease and increased film lifetime. Differences in the stability of the foams and foam were explained with the different molecular structure and different aggregation behavior of the two protein types. Far from its isoelectric pI, casein adsorption layers are denser and thicker thus ensuring better stabilization. Added electrolyte increased further the adsorption and the repulsion between the surfaces (probably by steric and/or osmotic mechanism). In contrast the globular molecules of WPC probably could not compact well to ensure the necessary films and foams stabilization far from pI, even after electrolyte addition.

The relation between protein structure, interfacial rheology and foam formation for various milk proteins

A number of purified milk protein preparations (caseins as well as whey proteins, including naturally occurring genetic variants) were investigated for their interfacial and foaming properties. Relations were found between the structure of a protein and its ability to spread and form a coherent film at the air-water interface, as well as with the foaming properties.

Stability and mechanical strength of aqueous foams containing food proteins

Colloids and Surfaces A-physicochemical and Engineering Aspects, 1995

The role of proteins in the formation and stabilization of foams is important in many food applications. Most such products are made with egg white or milk proteins as emulsifiers. This study is concerned with the foaming properties of high-quality caseins and ovalbumin, as model food systems. The foaming properties (foam strength and stability) were evaluated in an aeration column (bubbling method). Foams were generated with several well-known food proteins: casein, acid casein, sodium caseinate, calcium caseinate, and ovalbumin. Experimental conditions varied as follows: (a) temperature between 5 and 40°C; (b) protein concentration from 0.01 to 1% (w/w); (c) pH between 2 and 9; and (d) ethanol and sucrose were added to distilled water to produce solutions of concentrations between 0 and 1 M. A second-order kinetics model is a satisfactory mathematical description of the foam drainage behaviour, so the discussion of the results is based on the second-order rate constant for drainage. It was observed that intrinsic molecular properties (the nature and extent of protein-protein interactions), as well as environmental and processing factors (temperature, pH and viscosity of the continuous phase) affected the foaming properties. Moreover, foams with enhanced mechanical strength (greater protein-protein interactions) were more stable.

Interfacial properties, film dynamics and bulk rheology: A multi-scale approach to dairy protein foams

Journal of Colloid and Interface Science, 2019

Hypothesis: The effective contribution of interfacial properties to the rheology of foams is a source of many open questions. Film dynamics during topological T1 changes in foams, essentially studied for low molecular weight surfactants, and scarcely for proteins, could connect interfacial properties to protein foam rheology. Experiments: We modified whey protein isolate (WPI), and its purified major protein b-lactoglobulin (b-lg) by powder pre-conditioning and dry-heating in order to obtain a broad variety of interfacial properties. We measured interfacial properties, film relaxation duration after a T1 event and bulk foam rheology. Findings: We found that, for b-lg, considered as a model protein, the higher the interfacial elastic modulus, the longer the duration of topological T1 changes and the greater the foam storage and loss moduli and the yield stress. However, in the case of the more complex WPI, these correlations were less clear. We propose that the presence in WPI of other proteins, lactose and minerals modify the impact of pre-conditioning and dry-heating on proteins and thereby, their behaviour at the interface and inside the liquid film.

How foam stability against drainage is affected by conditions of prior whey protein powder storage and dry-heating: A multidimensional experimental approach

Journal of Food Engineering, 2019

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Effect of Acid Treatment on Interfacial and Foam Properties of Soy Proteins

Journal of Food Science and Engineering, 2015

The goal of the present work was to study the effects of acid treatment on the foaming properties of a soybean protein isolate (SPI) and its fractions, glycinin (11S) and β-conglycinin (7S). The structural characteristics, interfacial properties, foaming capacity and stability of the treated proteins were studied. Results from surface hydrophobicity and differential scanning calorimetry (DSC) showed that the acid treatment caused the complete denaturation of 11S and a partial denaturation of 7S. This protein unfolding affected their interfacial properties, which led to an improvement in the foaming properties of both protein fractions and isolate. Treated 7S showed the best behavior in the rearrangement process, probably due to its smaller size and its modified structural characteristics. All treated proteins showed stronger interfacial films. The foams of treated proteins were destabilized mostly due to gravitational drainage rather than Ostwald ripening.

High pressure effect on foaming behaviour of whey protein isolate

Journal of Food Engineering, 2001

The eect of pressure-processing at 150±450 MPa for 5±25 mm on foaming behaviour of whey protein isolate (WPI) have been investigated in pH range of 5.0±7.0. Assessment of foaming properties has been based on the total foam volume (FV) produced and the foam stability (FS), and the time for loss of half the initial FV. Response surface methodology has been applied to ®nd the regression equations for predicting the FV and FS in terms of independent variables (the intensity of pressure, the treatment time and the pH). Protein solutions (1% w/v, 50 mM phosphate buer) were pressure-processed and foams were produced from dilute solutions of WPI (0.005% w/v) by sparging with nitrogen gas at constant¯ow rate (0X2 AE 0X01 dm 3 /min) and constant temperature (20°C). It has been found that pH is signi®cant (P 6 0X01) on both FV and FS; FV is in¯uenced signi®cantly (P 6 0X05) by pressureintensity whereas the eect of pressure-treatment time on either FV or FS is not signi®cant (P 6 0X05). Foaming properties of WPI were reduced as the pH approached to the isoelectric point of proteins due to enhanced aggregation. Pressurisation at high-protein concentration (2% w/v) or in high-buer molarity (100 mM) has been observed to diminish the foaming properties of WPI.

Foaming Properties of Soy Protein Isolate Hydrolysates

Journal of Food and Nutrition Sciences, 2015

Tensoactive species obtained by papain hydrolysis of soy protein were characterized structurally and physicochemically, and their foam-forming and-stabilizing capacity studied. Protein structural changes upon reaction ending were correlated with functional and interfacial properties and with the behaviour thereof with varying hydrolysis degree. Two different means of halting hydrolysis-pH reduction (pH=2) and quick freezing (-18 ºC), respectively-were studied. Distinct structural changes and associated functional properties were found according to reaction ending conditions. No improvement of foaming properties was found for partially-hydrolyzed isolates subject to freezing at reaction ending-with respect to the starting unhydrolyzed soy protein isolate. In contrast, pH treatment as a means of halting hydrolysis led to a significant enhancement of the foaming properties of soybean protein hydrolysates consistently for all studied hydrolysis degrees (0%, 1.8%, 2.5% and 6%).

Combined effect of dynamic heat treatment and ionic strength on the properties of whey protein foams – Part II

Food Research International, 2008

The aim was to investigate the effect of dynamic thermal treatment in a tubular heat exchanger on the denaturation and foaming properties of whey proteins, such as overrun, foam stability and texture. A 2% w/v WPI solution (pH 7.0), with and without NaCl addition (100 mM), was submitted to heat treatment at 100°C. The results demonstrated that heat treatment slightly reduced overrun, whereas NaCl and heat treatment improved foam stability, enhanced texture and provided smaller bubble diameters with more homogeneous bubble size distributions in foams. The foaming properties of proteins, especially stability, were shown to depend not only on the amount of protein aggregates, but also on their size. While insoluble aggregates (larger than 1 lm diameter) accelerated drainage, soluble aggregates (about 200 nm diameter) played a key role on the stabilization of gas-liquid interfaces.

New View to Obtain Dryer Food Foams with Different Polysaccharides and Soy Protein by High Ultrasound

International Journal of Carbohydrate Chemistry, 2014

The objective of this work was to determine the effects of high intensity ultrasound application on the foaming properties of soy protein-polysaccharides mixed solutions. To this end, foaming parameters during foam formation were analyzed. The samples were sonicated for 20 min using ultrasonic processor Vibra Cell Sonics, and model VCX 750 at a frequency of 20 kHz and an amplitude of 20%. The foams were produced by a Foamscan instrument. The evolution of the bubble size change in the foam was also determined by a second CCD camera. For all foamed systems, at two pHs 3 and 7, Foam expansion and Relative Foam Conductivity showed a great increase after ultrasonic treatment. Other parameters studied did not show difference. On the other hand, Final Time of Foaming and the Total Gas Volume incorporation for foams formation were correlated with the Relative Foam Conductivity decrease and the Foam Expansion increase when HIUS were applied in every system. Comparative bubble size and shape ...

Modification of foaming properties of soy protein isolate by high ultrasound intensity: Particle size effect

Ultrasonics Sonochemistry, 2015

The effect of high intensity ultrasound (HIUS) may produce structural modifications on proteins through a friendly environmental process. Thus, it can be possible to obtain aggregates with a determined particle size, and altering a defined functional property at the same time. The objective of this work was to explore the impact of HIUS on the functionality of a denatured soy protein isolate (SPI) on foaming and interfacial properties. SPI solutions at pH 6.9 were treated with HIUS for 20 min, in an ultrasonic processor at room temperature, at 75, 80 and 85°C. The operating conditions were: 20 kHz, 4.27 ± 0.71 W and 20% of amplitude. It was determined the size of the protein particles, before and after the HIUS treatment, by dynamic light scattering. It was also analyzed the interfacial behavior of the different systems as well as their foaming properties, by applying the whipping method. The HIUS treatment and HIUS with temperature improved the foaming capacity by alteration of particle size whereas stability was not modified significantly. The temperature of HIUS treatment (80 and 85°C) showed a synergistic effect on foaming capacity. It was found that the reduction of particle size was related to the increase of foaming capacity of SPI. On the other hand, the invariable elasticity of the interfacial films could explain the stability of foams over time.