US Patent 7771528 Processing for producing zein articles with limited solubility

Zein articles are prepared by a melt process where zein is mixed with glyoxal and an inorganic base solution at temperatures above about 40° C. The melt processing can take as a batch process (e.g., as in a torque rheometer) or in a continuous process (e.g., as in reaction extrusion using a screw extruder). This process provides a zein article that has greatly reduced solubility in most of the standard organic solvents that will dissolve unaltered zein.