Abstract: The present invention is a method for protein isolation as a co-product of alcohol production. The method includes receiving grain product at a holding receptacle, the grain product being at least one of whole stillage, dried distillers grain, and wet distillers grain. The method further includes directing the grain product from the holding receptacle over a plurality of screens, thereby allowing a fiber-containing portion of the grain product to be collected on the plurality of screens and further allowing a protein-containing portion of the grain product and an oil-containing portion of the grain product to pass through the plurality of screens.