Cereal Chem. 70:115-121   |  VIEW ARTICLE

Water-Soluble Zein by Enzymatic Modification in Organic Solvents.

A. Mannheim and M. Cheryan. Copyright 1993 by the American Association of Cereal Chemists, Inc. 

Water-soluble zein was produced using a dual-phase, sequential enzymatic modification and ultrafiltration. Zein was first partially hydrolyzed in an organic solvent by a protease, followed by an aqueous phase hydrolysis with the same protease. Ultrafiltration of the reaction mixture with a 10,000 and/or a 30,000 molecular weight cut-off membrane yielded fractions with an average of 5,400 Da. A significant improvement in certain functional properties of zein was observed, controlled largely by the degree of hydrolysis (DH). Solubility increased from 0% for the unmodified zein to 99% for enzyme-modified and ultrafiltered zein. At less than DH20, solubility was also a function of pH and membrane pore size. Foaming properties were affected by DH, membrane pore size, and pH of measurement. At a water activity of 0.97, moisture sorption was 2.6 g of water per gram of solids for the enzyme-modified and ultrafiltered hydrolysates, compared to less than 0.25 g of water per gram of solids for unmodified zein.