Egg White Protein Foams Research Articles

Effect of bacterial cellulose on the foaming properties of egg white and soy proteins

Food foams are highly industrially relevant systems, responsible for the visual appearance and organoleptic properties of many processed foods. Foam characteristics can be further improved by food-grade additives. This study investigates the influence of bacterial cellulose (BC) on the foaming capacity (FC) and foam stability (FS) of egg white protein (EWP) and soy protein isolate (SPI), important food foaming agents. The effects of pH, BC concentration and particle size on the FS and FC were analyzed. Compared to SPI, EWP demonstrated higher FC, an effect that is tentatively assigned to its lower molecular weight, hence faster diffusion to the interface. Adding 0.1 % BC to EWP (4 %, at pH 7.0) and to SPI (4 %, at pH 3.0) increased the FC by 1.6 and 1.5 times, respectively. The addition of BC also reduced the foam's liquid drainage, although not impacting the FS. Surprisingly, large flakes of BC (Dv(50) of 1104 µm) yielded higher FC values than smaller ones. We hypothesize that larger BC flakes may act as anchoring sites, stabilizing the air bubbles during whipping. BC flakes were observed in the plateau borders and nodes of EWP foams, clogging the water channels and preventing drainage. This work demonstrates the potential of BC as a food-grade foam enhancer, providing a new tool for the food engineer´s arsenal.

Protein foam application for enhanced oil recovery

ABSTRACTProtein foam was explored as a foaming agent for enhanced oil recovery application in this study. The influence of salinity and oil presence on bulk stability and foamability of the egg white protein (EWP) foam was investigated. The results were compared with those of the classical surfactant sodium dodecyl sulfate (SDS) foam. The results showed that the EWP foam is more stable than the SDS foam in the presence of oil and different salts. Although, the SDS foam has more foamability than the EWP foam, however, at low to moderate salinities (1–3 wt% NaCl), both foam systems showed improvement in foamability. At a NaCl concentration of 4.0 wt% and above, foamability of the SDS foam started to decrease drastically while the foamability of the EWP foam remained the same. The presence of oil has a destabilizing effect on both foams but the EWP foam was less affected in comparison to the SDS foam. Moreover, increasing the aromatic hydrocarbon compound percentage in the added oil decreased the foamability and stability of the SDS foam more than EWP foams. This study suggests that the protein foam could be used as an alternative foaming agent for enhanced oil recovery application due to its high stability compared to the conventional foams.

The analysis of the influence of xanthan gum and apple pectins on egg white protein foams using the large amplitude oscillatory shear method

This research study analysed the rheological properties of fresh food foams based on egg white protein, and with the addition of apple pectins and xanthan gum. The rheological analysis was carried out using the large amplitude oscillatory shear (LAOS) technique. From the obtained results two types of Lissajous figures were constructed, describing the elastic and viscous properties. The obtained figures were subjected to geometrical decomposition, which resulted in the determination of the stress values characteristic of nonlinear purely elastic and purely viscous properties. The Fast Chebyshev Transform allowed for the calculation of the Chebyshev coefficients, and further detailed analysis of rheological behaviour of foams as a function of strain amplitude. The determination of the values of elastic and viscous Chebyshev coefficients allowed for the interpretation, with high resolution, of nonlinear rheological properties of the obtained foams.

The effect of pectins and xanthan gum on physicochemical properties of egg white protein foams

The study analyzed the influence of the degree of apple pectin methylation and the concentration of xanthan gum on physicochemical properties of fresh wet egg white protein based foams. Molecular characterization of applied hydrocolloids was performed and amino acid composition of proteins was established. First, essential physicochemical properties of the starting solutions, i.e. density, surface tension and hydrophobicity, were analyzed, and electrophoretic analysis of the solutions was carried out. Density and content of the gaseous phase in the continuous phase were determined. The image analysis allowed assessment of the size distributions of gas bubbles and, subsequently, cross compliance of the population of obtained bubbles was performed using the Kolmogorov–Smirnov test. Next, using the maximum likelihood method, three distributions, i.e. Weibull, log-normal and gamma distributions, were matched to one another. The results showed that the log-normal distribution provided the best description of the bubble distribution.

The role of hydrocolloids in mechanical properties of fresh foams based on egg white proteins

The paper presents results of studies on the preparation of fresh food foams based on egg white and hydrocolloids (xanthan gum and carrageenan). The basic physical parameters of the obtained foams such as density, gas volume fraction and size of gas bubbles were measured. Rheological measurements were also performed, and continuous Maxwell model was applied to describe viscoelastic properties. The analysis of the obtained results concerned the impact of individual hydrocolloids and their mixtures on the changes of the rheological properties as well as their influence on the stability of the obtained foams. It was shown, that addition of pure xanthan preserved native properties of the egg white protein foams; the resulting foams, however, created difficulties during further processing. Foams containing only carrageenan were unstable, but exhibited desirable rheological properties. As a result of mixing xanthan gum and carrageenan, stable viscoelastic foams with unique rheological and technological properties were obtained.

The stability and physical properties of egg white and whey protein foams explained based on microstructure and interfacial properties

The goal of this investigation was to determine if physical models, based on micro-scale (bubbles) and nano-scale (interface) properties, can be used to explain the macroscopic foaming properties of egg white protein (EWP) and whey protein isolate (WPI). Foam properties were altered by adding different amounts of sucrose (4.27–63.6 g/100 mL) and microstructures were observed using confocal laser scanning microscopy and bubbles were quantitatively measured using image analysis. Addition of sucrose decreased the initial bubble size, corresponding to higher foam stability and lower air phase fraction. EWP foams were composed of smaller bubbles and lower air phase fractions than WPI foams. Increased sucrose concentration caused a decreased liquid drainage rate due to a higher continuous phase viscosity and smaller bubble sizes. WPI foams had faster rates for liquid drainage and bubble coarsening than EWP foams. The differences were attributed to faster bubble disproportionation in WPI foams, caused by lower interfacial elasticity and lower liquid phase fractions. The experimentally fitted parameters for foam yield stress did not follow universal trends and were protein type dependent. EWP foams had higher yield stress than WPI foams due to smaller bubble sizes and higher interfacial elasticity. The yield stress of WPI foams increased slightly with addition of sucrose and cannot be accounted for based solely on model parameters. It appears that changes in stability of EWP and WPI foams can be explained based on physical models while unaccounted for protein-specific effects remain regarding foam yield stress.

Comparative effect of thermal treatment on the physicochemical properties of whey and egg white protein foams

The optimization of the functionalities of commercial protein ingredients still constitutes a key objective of the food industry. Our aim was therefore to compare the effect of thermal treatments applied in typical industrial conditions on the foaming properties of whey protein isolate (WPI) and egg white proteins (EWP): EWP was pasteurized in dry state from 1 to 5 days and from 60 °C to 80 °C, while WPI was heat-treated between 80 °C and 100 °C under dynamic conditions using a tubular heat exchanger. Typical protein concentrations of the food industry were also used, 2% (w/v) WPI and 10% (w/v) EWP at pH 7, which provided solutions of similar viscosity. Consequently, WPI exhibited a higher foamability than EWP. For WPI, heat treatment induced a slight decrease of overrun when temperature was above 90 °C, i.e. when aggregation reduced too considerably the amount of monomers that played the key role on foam formation; conversely, it increased foamability for EWP due to the lower aggregation degree resulting from dry heating compared to heat-treated WPI solutions. As expected, thermal treatments improved significantly the stability of WPI and EWP foams, but stability always passed through a maximum as a function of the intensity of heat treatment. In both cases, optimum conditions for foam stability that did not impair foamability corresponded to about 20% soluble protein aggregates. A key discrepancy was finally that the dry heat treatment of EWP provided softer foams, despite more rigid than the WPI-based foams, whereas dynamically heat-treated WPI gave firmer foams than native proteins.

Foams Prepared from Whey Protein Isolate and Egg White Protein: 2. Changes Associated with Angel Food Cake Functionality

The effects of sucrose on the physical properties and thermal stability of foams prepared from 10% (w/v) protein solutions of whey protein isolate (WPI), egg white protein (EWP), and their combinations (WPI/EWP) were investigated in wet foams and angel food cakes. Incorporation of 12.8 (w/v) sucrose increased EWP foam stability (drainage 1/2 life) but had little effect on the stability of WPI and WPI/EWP foams. Increased stability was not due to viscosity alone. Sucrose increased interfacial elasticity (E ') of EWP and decreased E' of WPI and WPI/EWP combinations, suggesting that altered interfacial properties increased stability in EWP foams. Although 25% WPI/75% EWP cakes had similar volumes as EWP cakes, cakes containing WPI had larger air cells. Changes during heating showed that EWP foams had network formation starting at 45 degrees C, which was not observed in WPI and WPI/EWP foams. Moreover, in batters, which are foams with additional sugar and flour, a stable foam network was observed from 25 to 85 degrees C for batters made from EWP foams. Batters containing WPI or WPI/EWP mixtures showed signs of destabilization starting at 25 degrees C. These results show that sucrose greatly improved the stability of wet EWP foams and that EWP foams form network structures that remain stable during heating. In contrast, sucrose had minimal effects on stability of WPI and WPI/EWP wet foams, and batters containing these foams showed destabilization prior to heating. Therefore, destabilization processes occurring in the wet foams and during baking account for differences in angel food cake quality.

Foams Prepared from Whey Protein Isolate and Egg White Protein: 1. Physical, Microstructural, and Interfacial Properties

Foams were prepared from whey protein isolate (WPI), egg white protein (EWP), and combinations of the 2 (WPI/EWP), with physical properties of foams (overrun, drainage 1/2 life, and yield stress), air/water interfaces (interfacial tension and interfacial dilatational elasticity), and foam microstructure (bubble size and dynamic change of bubble count per area) investigated. Foams made from EWP had higher yield stress and stability (drainage 1/2 life) than those made from WPI. Foams made from mixtures of EWP and WPI had intermediate values. Foam stability could be explained based on solution viscosity, interfacial characteristics, and initial bubble size. Likewise, foam yield stress was associated with interfacial dilatational elastic moduli, mean bubble diameter, and air phase fraction. Foams made from WPI or WPI/EWP combinations formed master curves for stability and yield stress when normalized according to the above-mentioned properties. However, EWP foams were excluded from the common trends observed for WPI and WPI/EWP combination foams. Changes in interfacial tension showed that even the lowest level of WPI substitution (25% WPI) was enough to cause the temporal pattern of interfacial tension to mimic the pattern of WPI instead of EWP, suggesting that whey proteins dominated the interface. The higher foam yield stress and drainage stability of EWP foams appears to be due to forming smaller, more stable bubbles, that are packed together into structures that are more resistant to deformation than those of WPI foams.

Properties of whey and egg white protein foams

Abstract Foams made of varying concentrations (2–20% w/v protein) of egg white and whey protein isolate were compared by measuring rheological and microstructural properties. Egg white proteins formed foams with higher yield stress (τ) at lower protein concentrations and less whipping time than whey protein isolate foams. The model of Princen and Kiss [J. Coll. Interf. Sci. 128 (1989) 176] predicts a relationship among τ, surface tension (σ), phase volume (φ), and bubble size (R32). This was supported by τ increasing with φ, and the relationship between τ and φ1/3 becoming more linear as protein concentration increased. However, egg white foams had yield stress values as much as 100 Pa greater than whey protein foams, despite having similar phase volumes, bubble size, and lower surface tensions. The experimentally determined factors, Y(φ), for egg white and whey protein isolate foams were within the range determined by Princen and Kiss [J. Coll. Interf. Sci. 128 (1989) 176] for concentrated emulsions. Egg white foams were different in that the values for Y(φ) increased at lower phase volumes than for whey protein isolate foams or concentrated emulsions. These results suggest that specific proteins contribute to foam τ by some means in addition to altering surface properties.

Measurement of the Yield Stress of Protein Foams by Vane Rheometry

ABSTRACT:The yield stresses of protein foams made from varying protein types (spray dried egg white and whey protein isolate), protein concentrations, whip times, and mixer models were evaluated using vane rheometry. Two methods of analysis (point and slope methods) were investigated. Yield stress values determined by slope and point methods were similar for egg white protein foams but did not agree in the analysis of whey protein foams. Point method values were very reproducible in all foams tested. Egg white protein solutions formed stiffer foams more rapidly and at lower protein concentrations than foams made from whey protein isolate. Vane rheometry was shown to be a reliable method of determining yield stress in protein foams.