Zein has been commercially available for over 60 years and is primarily used as a coating for papers, but because it is difficult to process the scope of application has been limited.

That is until now. ARS says that its scientists have been reviewing ways to eliminate the the odor and yellow color that have made the substance difficult to use in commercial applications such as cosmetic formulations.

Hydrogel and microsphere polymers

Chemist David Sessa has been working on this problem at the ARS Nation Center for Agricultural Utlization, in Peoria Illinois - work that has culminated in an advanced purifying method that has sporned the development of hydrogel and microsphore polymers.

Hydrogel polymers are particularly useful for their water absorbency properties and are commonly used in diapers and contact lens solutions. Microsphore polymers are hollow spheres that are frequently used in cosmetics formulations to give a smooth silky feel.

Sessa says that he was able to develop the two polymers by taking a ground up approach to the purification process of zein, tackling the conventional method, which loses between 37 – 95 per cent of the corn protein in the process

Ineffecient purifying process

The reason why the process is so inefficient is that existing purification processes for zein use activated carbons (AC), which are poros and charcoal-like. This means it blends with the purified protein, causing the odor and yellow coloring.

With the aim of developing a more efficient and less costly purification process, Sessa has used several alternative methods of purification that appear to bear improved results, leading to the development of the two new polymers.

The first, and it seems the most promising, is based on ‘zeolites’, a silicate of clay particles, whose pores act as molecular sieves, causing the odor and color to be trapped during the purification process. This helped improve zein yields by 25 percent.

The other two methods relied on are ultraviolet light and an algorithm-controlled system, both of which are in earlier stages of investigation.