Proteins gelation mechanism

When a protein dispersion is heated a gel may form. The gelation mechanism, the gel structure and the gel properties are highly dependant on processing conditions as well as factors such as pH and ionic strength. Differences in gel structures are demonstrated in Finures 1 and 2. where electromicrographs of two gel structures of exactly the same protein preparation, formed at different ionic strengths are shown. 

Domain coalescence (Karplus and Weaver, 1976) is a possible mechanism for protein folding. Zientara et al. (1980) examined the dependence of the coalescence lifetime on the hydration shell. The lifetime depends on the activation barrier contributed by the shell and the extent of the shell. If domains resemble the native protein in hydration, then the minimal extent of the shell and its fluidity favor coalescence. In passing, one notes that the percolation model may apply to folding the coalescence of domains should be analogous to gelation or to diffusion on a partially filled lattice. 

Starches and proteins are main ingredients in many food formulations. The mechanism of starch reinforcement in a protein-starch composite matrix relies upon the fractions of both macromolecules as well as the water availability, gelation temperature of a continuous matrix, volume fraction of the separated phase, or filler and mechanical strength of the fillers in relation to the continuous matrix, as previously described. Generally, the reinforcement could be obtained by increasing the volume fraction of the filler (Richardson et al., 1981 Ross-Murphy and Todd, 1983). 

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