A continuous multi-zone convection system that provides optimal drying/roasting in a gentle, and sanitary manner. First-in, first-out production and even heating with a smart, step-spiral, and flighted drum design achieves uniform drying and roasting. Energy-efficient, product-focused heating maximizes heat transfer and reduces heat loss with heated air that’s focused only into the product bed and nowhere else. Positive temperature control offers unmatched product uniformity as the dryer/roaster automatically regulates its own internal temperature. A variety of product characteristics is possible by utilizing multiple processing zones. IDEAL APPLICATIONS include: Nuts and dough-coated nuts Seeds Jerky Meat chips and protein-based snacks Pet treats Pellet snacks Pork rinds