A representative sample shall have been examined to determine fat and moisture content. One sample unit from each vat of cheese shall have been examined to determine the suitability of the vat for use in process cheese products in accordance with the flavor, body and texture characteristics permitted in §§58.711 through 58.714 as applicable, and to determine the characteristics it will contribute to the finished product when blended with other cheese. The cheese included in each blend shall be selected on the basis of the desirable qualities which will result in the desired finished product. Recook from equivalent blends may be used in an amount that will not adversely affect the finished product. Hot cheese from the filler may be added to the cooker in amounts which will not adversely affect the finished product.