Effect of heat treatment on the dispersion performance of casein superplasticizer used in dry-mix mortar

The influence of heat exposure during production of casein on its plasticizing effectiveness was investigated. A model self leveling underlayment (SLU) formulation was used to assess the dispersing power of casein. It was found that elevated temperature and long exposure times can induce chemical changes in the casein proteins which reduce their performance. Particularly, crosslinking accompanied by partial decomposition (denaturation) of the casein biopolymer as evidenced by fast protein liquid chromatography and gel permeation chromatography was found to be responsible for reduced dispersing power. As an optimum drying condition, a temperature of 110 °C and a short exposure time of up to 2 h are recommended. Under this condition, the wet casein rapidly releases its water while maintaining its full dispersion power. Understanding the temperature and exposure-time dependent behavior of casein proteins can help to produce more consistent casein qualities.