Protein stabilizing foams

Hailing, P.J., Protein Stabilized Foams and Emulsions, CRC Critical Reviews in Food Science And Nutrition, 155 (1981). 

Damodaran, S. (2005). Protein stabilization of emulsions and foams. Journal of Food... 

Figure 7.16 Dependence on tlie polysaccharide concentration CDS of (a) tlie second virial coefficient A2 and (b) tlie stmcture-sensitive parameter p of complexes of sodium caseinate + dextran sulfate , complexes prepared in bulk solution a, complexes prepared at tlie interface in a protein-stabilized foam , sodium caseinate alone. Reproduced from Semenova et al. (2009) with permission.

Clark, D.C., Mackie, A.R., Wilde, P.J., Wilson, D.R. (1994). Differences in the structure and dynamics of the adsorbed layers in protein-stabilized model foams and emulsions. 

For the studies presented in this chapter, samples of peanut and cottonseed meal suspensions were evaluated for foam capacity, stability, and viscosity measurements as described by Cherry and coworkers (23, 24, 22). Vegetable protein suspensions at the appropriate concentration and pH were whipped in a Waring-type blender. After blending, the whipped products were transferred to a graduated cyclinder. Milliliters of foam were recorded immediately and at various time intervals to determine capacity and stability. A Brookfield viscometer and... 

DNA is precipitated, the solution must be deproteinized. This is brought about by treatment with chloroform-isoamyl alcohol followed by centrifugation. Upon centrifugation, three layers are produced an upper aqueous phase, a lower organic layer, and a compact band of denatured protein at the interface between the aqueous and organic phases. Chloroform causes surface denaturation of proteins. Isoamyl alcohol reduces foaming and stabilizes the interface between the aqueous phase and the organic phases where the protein collects. 

Damodaran, S. Protein-Stabilized Foams and Emulsions in Food Proteins and Their Applications, Damodaran, S. Paraf, A. (Eds.), Dekker, New York, 1997, pp. 57-110. 

It is not uncommon among North Coast winemakers to add bentonite, one to three pounds per 1000 gallons, to the fermenting juice. This has been done to reduce fermentation foam and promote protein stability in the finished wine. Ough and Amerine confirmed the action of bentonite in helping stabilize the wine for protein (26). More recently, Vos and Gray (18) observed that bentonite treatment of must, prior to fermentation, reduced protein concentration and H2S development while fermentation conducted in contact with bentonite increased H2S production. 

Hailing, P.J. 1981. Protein-stabilized foams and emulsions. CRC Crit. Rev. Food Sci. Nutr. 15,155-203. 

In protein-stabihzed foams, protein flexibility is critical to the molecule functionality in stabilizing interfaces (Hailing 1981 Lemeste et al. 1990). This has important consequences in the development and stability of dairy foams and emulsions, where the heat treatment received by the material can define its foamability and dispersion properties. A symbiotic effect between native and denatured proteins on the emulsifying properties of whey proteins isolate blends has been observed by (Britten et al. 

Elizalde, B E., Giaccaglia, D., Pilosof, A.M.R., and Bartholomai, G.B. (1991). Kinetics of liquid drainage from protein-stabilized foams. J. Food Sci. 56, 24-26. 

In contrast to protein stabilized foams the foam formation and stabilization mechanisms in whipping cream are supposed to depend on the bubble stabilization by means of fat rather than proteins. The fat content can therefore not be less than 30% butterfat, and whipping cream is expected to fulfil certain criteria, namely whipping time, foam firmness, foam volume increase (or overrun), and volume of dripping-off (or drainage). 

Emulsion stability is required in many dairy applications, but not all. In products like whipped cream and ice cream, the emulsion must be stable in the liquid form but must partially coalesce readily upon foaming and the application of shear. The structure and physical properties of whipped cream and ice cream depend on the establishment of a fat-globule network. In cream whipped to maximum stability, partially coalesced fat covers the air interface. In ice cream, partially coalesced fat exists both in the serum phase and at the air interface also, there is more globular fat at the air interface with increasing fat destabilization. Partial coalescence occurs due to the collisions in a shear field of partially crystalline fat-emulsion droplets with sufficiently-weak steric stabilization (low level of surface adsoiption of amphiphilic material to the interface per unit area). To achieve optimal fat crystallinity, the process is very dependent on the composition of the triglycerides and the temperature. It is also possible to manipulate the adsorbed layer to reduce steric stabilization to an optimal level for emulsion stability and rapid partial coalescence upon the application of shear. This can be done either by addition of a small-molecule surfactant to a protein-stabilized emulsion or by a reduction of protein adsorption to a minimal level through selective homogenization. 

Interactions between proteins and polysaccharides give rise to various textures in food. Protein-stabilized emulsions can be made more stable by the addition of a polysaccharide. A complex of whey protein isolate and carboxymethylcellulose was found to possess superior emulsifying properties compared to those of the protein alone (Girard et al., 2002). The structure of emulsion interfaces formed by complexes of proteins and carbohydrates can be manipulated by the conditions of the preparation. The sequence of the addition of the biopolymers can alter the interfacial composition of emulsions. The ability to alter interfacial structure of emulsions is a lever which can be used to tailor the delivery of food components and nutrients (Dickinson, 2008). Polysaccharides can be used to control protein adsorption at an air-water interface (Ganzevles et al., 2006). The interface of simultaneously adsorbed films (from mixtures of proteins and polysaccharides) and sequentially adsorbed films (where the protein layer is adsorbed prior to addition of the polysaccharide) are different. The presence of the polysaccharide at the start of the adsorption process hinders the formation of a dense primary interfacial layer (Ganzelves et al., 2008). These observations demonstrate how the order of addition of components can influence interfacial structure. This has implications for foaming and emulsifying applications. 

As a rule, the fluid dispersions (emulsions, foams) are stabilized by adsorption layers of amphiphile molecules. These can be ionic and nonionic surfactants, lipids, proteins, etc. All have the property to lower the value of the surface (or interfacial) tension, o, in accordance with the Gibbs adsorption... 

Crotein. [Croda Inc. Croda Chem. Lul.] Animal and wheat protein derivs. conditioner, film modifier, foam booster/ stabilizer, dye leveling agent for hair care prods., nail enainks moisturizer for sldn care prods. 

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