Gelation of proteins

Protein Source and Variety - By choosing a particular protein, one may increase a particular functionality for example, increased sulfur amino acid concentration will enhance gelation of protein ingredients. 

It has been found that substances like sulphates, tartarates, acetates, citrates promote the rate of gelation, whereas certain substances like chlorides, nitrates etc. retard the rate of gelation. The gelation of proteins is retarded by acid and alkalies. 

Hamann, D. D. 1987. Methods for measurement of rheological changes during thermally induced gelation of proteins. Food Technol. 41(3) 100, 102-108. 

In spite of the above limitations and the relatively small number of Studies involved, it is evident that the functionality of proteins as protein concentrates can be modified substantially by enzymes. Solubilities of proteins can be altered (generally increased) by hydrolytic reactions viscosities and gelation of protein solutions can be decreased dramatically by limited proteolysis the volume of foams of whipped hydrolysates is generally greater than that of the parent protein, but the foam stability is usually less. Emulsification properties of hydrolysates are affected in different ways depending on the protein. From the very limited number of studies on partial hydrolysis of food proteins it appears that water binding is increased as a result of proteolysis. ... 

Factors reported to be important in the gelation of proteins include pH, salt concentration, calcium concentration, protein hydropho-bicity, and free sulfhydryl concentration [39]. 

Gelation of proteins such as egg albumen and serum albumin is drought to be caused by parts of the hydrophobic side chains. These side chains are exposed on the outside of die globular protein molecules by the addition of heat and die formation of a supramolecular assembly. This is done by placing globular particles side by side due to the balance of the hydro-phobic interaction and ionic repulsion. (See Table 2 for more information.)... 

Le Bon, C., Nicolai, T., and Durand, D., Kinetics of Aggregation and gelation of globular proteins after heat-induced denaturation, Macromolecules, 32,6120, 1999. 

Aromatic side chains of amino acids such as phenylalanine, tryptophan, and tyrosine are found in general in the interior of proteins, in hydrophobic regions. In some proteins they mediate helix-helix contacts. It is to be expected that agents containing aromatic groups could interact with proteins via aromatic-aromatic interactions, as for instance, proven by X-ray studies of biphenyl compounds which inhibit sickle-cell hemoglobin gelation. 

Bolder, S.G., Hendrickx, H., Sagis, L.M.C., van der Linden, E. (2006). Ca2+-induced cold-set gelation of whey protein isolate fibrils. Applied Rheology, 16, 258- 264. 

Entrapping of bioactive ingredients by polymer matrix in gel or microgel particles heat-induced or cold-induced aggregation and gelation of globular proteins (microcapsules of 5-5000 pm)... 

Roff, C.F., Foegeding, E.A. (1996). Dicationic-induced gelation of pre-denatured whey protein isolate. Food Hydrocolloids, 10, 193-198. 

Van der Linden and Sagis (2001) have suggested that, once a critical concentration for gel formation is known, one can predict, for example, the dependence of the gel elasticity on the concentration of protein. The minimum gelation concentration may be expressed in terms of the basic fibre characteristics like the stiffness and also as a function of salt concentration (Veerman, 2004 Sagis et al., 2004). It is pointed out by van der Linden (2006) that there are two important factors which allow the manipulation of this minimum gelation concentration to an extremely low value. The first factor is that the nano-fibre should be robust against dilution. And the second is that the fibre should robust also with respect to other treatments, especially the adjustment of the pH. It would appear that each of these conditions is satisfied. 

Intermolecular - properties utilizing the ability of proteins to form junctions of its own molecules to themselves or to other components including viscosity, thickening, gelation, film formation, foaming, fiber formation, adhesion, cohesion, stickiness, hardness, complex formation, spreading, elasticity, and plasticity. 

---