Stability-related structural protein aggregation

In sodium chloride brine, the addition of proteins did not alter the pseudoplastic behavior of xanthan. In sea water, even with a long stabilization time for each measurement, stress values were not identical when the shear rate was increased or decreased, indicating a thixotropic behavior. Protein addition did not significantly enhance this phenomenon. Thus, thixotropy seems to be related rather to the presence of cations inducing an aggregation of xanthan chains than to the addition of proteins. Nevertheless, in sea water, the gel formed by the extra-addition of proteins seems to have a more compact consistency than that of the gel induced by multivalent ions alone. This was probably the result of a synergic effect, e.g. the expulsion of some water molecules from the interior of the gel network by proteins. Experiments such as the determination of the elasticity module could bring some complementary information about the structure of the gel formed in these two cases. 

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