Cooking snack foods

Snack food is cooked by providing it in a bed of moving, heated particles 12 such that the food is cooked by heat transfer from the heated particles. After cooking the snack food and particles are separated, e.g. by sieving, size exclusion, density difference, vibration or gravity. Preferably the particles include or comprise steel or other magnetic, ferromagnetic, ferrimagnetic or electro conductive material such that they may be heated using electromagnetic induction, and/or may be detected and/or separated after cooking using magnetic force. The particles may be ceramic or polymeric with steel parts or inclusions, e.g. hollow or core-filled spheres with metal walls, cores or inclusions. The particles may be spherical or near-spherical, may comprise first and second particles with different sizes and/or densities, and may have a size from 40µm to 5mm. The particles may have a monomodal or multimodal size distribution. The snack food pieces are preferably starch-based precursors which expand upon heating. The food may be cooked in a batch or continuous process, and the particles may be heated before or after adding the snack food.