Casein gelation

Heidebach, T., Forst, P., Kulozik, U. Transglutaminase-induced caseinate gelation for the microencapsulation of probiotic cells. Int. Dairy J. 19, 77-84 (2009)... 

Belyakova, L.E., Antipova, A.S., Semenova, M.G., Dickinson, E., Matia-Merino, L., Tsapkina, E.N. (2003). Effect of sucrose on molecular and interaction parameters of sodium caseinate in aqueous solution relationship to protein gelation. Colloids and Surfaces B Biointerfaces, 31, 31 46. 

Eliot, C., Dickinson, E. (2003). Thermoreversible gelation of caseinate stabilized emulsions at around body temperature. International Dairy Journal, 13, 679- 684. 

Home, D.S. (2002). Casein structure, self-assembly and gelation. Current Opinion in Colloid and Interface Science, 7, 456 461. 

We have seen earlier in this chapter how the self-assembly of casein systems is sensitively affected by temperature. Another thermodynamic variable that can affect protein-protein interactions in aqueous media is the hydrostatic pressure. Static high-pressure treatment causes the disintegration of casein micelles due to the dismption of internal hydro-phobic interactions and the dissociation of colloidal calcium phosphate. This phenomenon has been used to modify the gelation ability of casein without acidification as a consequence of exposure of hydrophobic parts of the casein molecules into the aqueous medium from the interior of the native casein micelles (Dickinson, 2006). High-pressure treatment leads to a reduction in the casein concentration required for gelation under neutral conditions, especially in the presence of cosolutes such as sucrose (Abbasi and Dickinson, 2001, 2002, 2004 Keenan et al., 2001). 

Abbasi, S., Dickinson, E. (2004). Gelation of t-carrageenan and micellar casein mixtures under high hydrostatic pressure. Journal of Agricultural and Food Chemistry, 52, 1705-1714. 

Ruis, H.G.M., Venema, P., van der Linden, E. (2007). Relation between pH-induced stickiness and gelation behaviour of sodium caseinate aggregates as determined by light scattering and rheology. FoodHydrocolloids, 21, 545-554. 

The existence of thermodynamically favourable interactions between two biopolymers influences their gel-forming ability in aqueous media. As an example, let us refer here to the effect of low-methoxyl amidated (LMA) pectin (DE = 30 %) on the gelation ability of sodium caseinate (Matia-Merino, 2003 Matia-Merino et al., 2004 Dickinson, 2008a,b). 

Lazaridou, A., Biliaderis, C.G. (2009). Concurrent phase separation and gelation in mixed oat p-glucans/sodium caseinate and oat p-glucans/pullulan aqueous dispersions. Food Hydrocolloids, 23, 886-895. 

Manoj, P., Kasapis, S., Chronakis, I.S. (1996). Gelation and phase separation in malto-dextrin-caseinate systems. Food Hydrocolloids, 10, 407 120. 

Other Protein Components. Other protein components In complex food systems and In protein Ingredient preparations may Interfere with or modify gelation reactions. Protein Interaction between whey protein and casein upon heating has a profound Influence on the characteristics of the casein gel structure In cheesemaking. Similarly protein Interactions are Important to meat structures. Protein-protein Interaction between soy and meat proteins has also been demonstrated with heat treatment (28). While concrete Interaction data have not been collected on protein gels formed from protein combinations, gelation properties of whey proteln/peanut flour blends have been Investigated GU) ... 

Although the gelation properties of whey proteins are of great importance in many foods (Mulvihill, 1992) and it is possible to form a weak gel in creams by the formation of a continuous network of fat globules, most important milk gels are those involving casein micelles which can be made to form a gel matrix either by isoelectric precipitation (acid-induced gel) or by the action of a proteolytic enzyme (rennet-induced gel). Both gel types... 

The crystallization of lactose in frozen concentrated milk has been associated with a denaluration of casein which ultimately appears as a gel structure in the thawed product. Gelation in frozen milk can be retarded by enzymic hydrolysis of pan ol the lactose before freezing or by addilion of a polyphosphate salt. 

Enzymatic gelation of partially heat-denatured whey proteins by trypsin, papain, pronase, pepsin, and a preparation of Streptomyces griseus has been studied (Sato et al., 1995). Only peptic hydrolysate did not form a gel. The strength of the gel depended on the enzyme used and increased with increasing DH. Hydrolysis of whey protein concentrate with a glutamic acid specific protease from Bacillus licheniformis at pH 8 and 8% protein concentration has been shown to produce plastein aggregates (Budtz and Nielsen, 1992). The viscosity of the solution increased dramatically during hydrolysis and reached a maximum at 6% DH. Incubation of sodium caseinate with pepsin or papain resulted in a 55-77% reduction in the apparent viscosity (Hooker et al., 1982). 

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