Process for producing water-resistant films from corn gluten meal

A process for producing a plastic material, comprising the steps:

• i) providing a corn gluten source as a first solid phase and a first liquid phase comprising an organic solvent;
• (ii) extracting solvent-soluble components of the corn gluten source into the first liquid phase;
• (iii) precipitating a first fraction of the solvent-soluble components out of the first liquid phase, involving cooling of the first liquid phase, resulting in a second solid phase including the first fraction of the solvent-soluble components and a second liquid phase including a second fraction of the solvent-soluble components;
• (iv) separating the second solid phase and the second liquid phase;
• and
• (v) recovering a flexible plastic material from the second liquid phase or recovering a hard plastic material from the second solid phase,
• wherein the process is performed without addition of plasticizer external to the source or with addition of less than 5% plasticizer external to the source relative to the total weight of the plastic material being recovered.