Hydration related properties of rennet casein/starch mixtures

Different starch types were examined for their effects on the hydration, solubility and viscosity of rennet casein dispersions to model the behaviour of these hydrocolloids in foods such as imitation cheese. Rennet casein dispersed with the aid of calcium-chelating salts and heat had a peak particle size and apparent viscosity at 40°C before both decreased due to protein solubilisation with heating to 80°C. The starches examined had little effect on the solubility of heated rennet casein dispersions. The apparent viscosity of starch/casein dispersions increased with heating, particularly in the case of dispersions with pre-gelatinised starches in the temperature range 22-60°C. Following heating, casein/starch mixtures had significantly increased apparent viscosities compared to casein only and changed the rheology of dispersions from dilatant to pseudoplastic behaviour.