Date of Award


Degree Name

Bachelor of Science


Pulp and Paper Technology


The effect of shear on aqueous alkaline protein solutions of casein and a medium viscosity soybean was studied. A Haake Rotovisco viscometer and an Eppenboch agitator were used as shear sources. The light scattering technique was employed to note the changes in molecular weight.

The protein solution was sheared at 20% solids, and clarified by centrifugation and filtration. The solutions were investigated with the light scattering photometer, at pH 10.3, 13% ammonium hydroxide (based on weight of protein), 23°C and between 0.2 and 2.0% concentration.

Results showed that denaturization, causing aggregation, resulted from pressure filtration during clarification of the protein solutions. Light scattering measurements on concentrations less than 0.5%, deviated from light-scattering theory. Casein aggregates decreased in molecular weight with shear. Shearing stresses apparently dissociate or disperse the protein molecule.