Sodium caseinate, foamed

On considering the foaming capacity of these systems, we have found a synergistic effect for complexes of sodium caseinate with phosphatidylcholine, i. e., a four-fold increase in the half-life the foam as compared to the pure protein foam in the range of experimental conditions studied (pH 5.5-7.0 ionic strength 0.001-0.01 M). We note also here that pure phosphatidylcholine did not give fine stable foams at all under these same experimental conditions. Thus, it is evident that food-grade sodium caseinate nanoparticles can potentially possess dual functionality in food... 

In support of the possibility to manipulate foam stability by changing the nature of protein assembly in the presence of surfactant, Table 6.3 shows a correlation between molecular parameters of protein-phospholipid complexes and the visual appearance of foams stabilized by them in solutions of different pH. The data indicate that the foams stabilized by complexes of phospholipid liposomes with sodium caseinate exhibit a dramatic increase in stability as compared to the corresponding pure protein foams. (The phospholipid sample by itself did not make fine stable foams at any of the concentrations investigated). 

Table 6.3 Effect of protein self-assembly, induced by interaction with lecithin, on the stability of foams stabilized by complexes of sodium caseinate (1 % w/v) with soy phospholipids Lipoid S-21 (1(T5 M) (Istarova et al., 2005 Semenova, 2007). Values of Mw and A 2 are presented for the protein with and without surfactant at three pH values. Also shown are photographs of foams recorded 9 minutes following foam preparation. In each of the images the volume of the glass vessel containing die foam is 10 ml. 

Sanchez, C.C., Rodriguez Patino, J.M. (2005). Interfacial, foaming and emulsifying characteristics of sodium caseinate as influenced by protein concentration in solution. Food Hydrocolloids, 19, 407 116. 

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.

Table 7.3 Relationship between molecular parameters (A2, p) of sodium caseinate (0.5 wt%) + dextran sulfate complexes at pH = 6.0 formed in the bulk and at the interface of a protein foam, and the corresponding properties (J43, Q of the bilayer and mixed emulsions (20 vol% oil, 0.5 wt% sodium caseinate) containing 0.1 or 1.0 wt% dextran sulfate (Jourdain et aL, 2008 Semenova et al., 2009).

Figure 7. Photomicrographs on the various drainage stages of a foam film containing 2 wt% sodium caseinate, at 40 °C. Film diameter 0.35 mm.

Enzymatic hydrolysis modifies the foaming properties of casein. Protamex hydrolysates of sodium caseinate (DH 0.5 and 1.0%) displayed increased foam expansion at pH 2, 8 and 10 as compared with unhydrolyzed caseinate (Slattery and FitzGerald, 1998). Hydrophobic peptides resulting from... 

Sodium caseinate Free casein components Highly soluble and very surface active Emulsions and foam products... 

An example of the bulk volume structure of foam-dried particles (e.g., maltodextrin/sodium caseinate powder) is shown in Fig. 6.3 (Schoonman et al, 2001). Here, the solid matrix, voids, open and closed pores and bubbles, micropores and cracks create a complex structure that affects both heat and mass transfer during drying. 

Fig. 63 Bulk volume of foam-dried particles (maltodextrin/sodium caseinate powder), according to Schoonman etal. (2001) 1 Solid matrix 2 Voids 3 Open pores 4 Closed pores 5 Cracks 6 Connected pores.

M.-L., Bisperink, C., Ubbink, J., 2001. The microstructure of foamed maltodextrin/ sodium caseinate powders A comparative study by microscopy and physical techniques. Food Res. Int. 34 913-929. 

FIGURE 4.12 Foam half-life time of 0.05 wt.% sodium caseinate solutions as function of mean drop diameter of soybean oil. (From Prins, A. Theory and practice of formation and... 

Superior foaming properties of milk have been obtained by addition of calcium complexing agents. Kelly and Burgess (1978) demonstrated that addition of sodium hexametaphosphate to milk protein concentrate solutions prepared by ultrafiltration improved foam volume and stability on whipping. The addition of EDTA to milk, which causes dissociation of the casein micelle, improved the foaming properties of milk (Ward et al., 1997). 

For the mainly oil-soluble Span 20 siufactant, however, the lifetimes are much less and films rupture prematurely, in line with predictions based on Bancroft s rule. At concentrations well above the CMC where the effective volume fraction of micelles is significant (>5 vol%), thin liquid films may drain in a stepwise fashion by stratification. This phenomenon, seen initially with foam films, was explained by the formation of periodic colloidal structures inside the film that results in layering of the micelles. At a step-transition, a layer of micelles leaves the film and the film thickness decreases by approximately the effective micellar diameter. It can also occur in emulsion films shown recently for hexadecane-aqueous sodium case-inate-hexadecane systems. The step-height seen of around 20 nm is very close to the measured diameter of the casein micelles of between 20 and 25 nm. The layering ultimately increases the lifetime of a film, but a critical film area exists below which step transitions are inhibited such thick films containing layers of micelles are even more stable. 

---