Refining cottonseed oil at high rates of shear

Summary

Ten crude cottonseed oils obtained from different areas in the South and Southwest were refined with and without the use of high-shear agitation in the step involving the initial mixing of the crude oil and caustic soda solution. In each instance the use of high shear produced a lower color in the refined oil. The improvement with some oils was not marked because they either refined very well by the ordinary method or failed for some unexplained reason to respond readily to high-shear mixing. However a good proportion of the oils which were quite dark after refining by the ordinary method refined to a much lighter oil when high shear was used.

It was established that in high shear refining the color of the refined oil decreased as the temperature at which high shear was used decreased, the time at high shear increased, and the rate at which shear was applied increased. However an increase in the latter above a certain value had no effect. Also it was found that the color of the refined oil decreased as the amount and strength of the caustic soda solution increased.

Absorption spectra of some of the processed oils indicated that high shear was more effective than ordinary mixing in removing from an oil the gossypol-like and carotenoid color bodies.