Most dry pet food is produced by extrusion. Ingredients are ground to a flour, mixed with water and steam, fed through a heated screw barrel (typical 130–150°C) under pressure, and forced through a die plate that shapes pellets. Pellets puff as the pressure releases. After extrusion, kibble is dried, cooled, and coated with fat and palatants. The high heat cooks starches and kills pathogens, but degrades some heat-sensitive nutrients — taurine, certain B vitamins, and amino acids like lysine — which are typically supplemented post-cook. Lower-throughput alternatives include baking, freeze-drying, and air-drying.