Abstract: A food product cooker comprises a first relatively low temperature above ambient heating compartment, a second relatively high temperature heating compartment, a third water rinsing and cooling compartment and a fourth chiller compartment. The food product is conveyed through the first, second and third compartments on a serpentine conveyor having a plurality of vertical flights. Steam is introduced into the first and second compartments beneath the conveyor and removed by a venting system from the top of the compartments in such a manner as to maintain a generally constant and uniform heating temperature throughout the respective compartments.