The product is mixed up by mixing paddles in an almost square, one – level, hopper. Rotating mixing paddles gently move the product in every direction to deliver the desired final structure. The clearance between the paddles and the hopper is minimal, so that there is no compression or squashing of product. PSS SOMs also optimize fast emptying because of the one – level hopper and two drain holes, minimize final product residue and thereby significantly reduce operating time between batches, and can eliminate cross contamination too.