Increasing the ionic strength will also change the hydrophobic interaction (salting out) even with NaCl. I don't think it is possible only to directly measure the hydrophobic part of the interaction to the exclusion of everything else .

Thanks to all researchers for their valid point. As I am working with the partially purified powders, and on characterizations showed the presence of uronic acids, proteins & intra elements. Whereas, during gel preparation of gels altering of pH, concentration and sugars were affecting the gel strength. Further, fitting of predicted weak gel food model also showed increase in network strength. However exact determination of compounding effects of weak forces of interaction is found to be very difficult. So suggest me any methods to find these kinds of interactions and link with gel strength.