The systems and methods of the present invention provide an economically feasible means of thermally processing items such as food products. In some embodiments, the thermal process is a pasteurization process. In other embodiments, the thermal process is a sterilization process. The thermal process utilizes a volumetric heating process to quickly and efficiently add heat energy to the item and then utilizes a surface heating process to obtain a relatively even, highly elevated, temperature throughout the item. In this way, the time required to perform various thermal processes, such as pasteurization and/or sterilization, is greatly reduced compared with traditional processes while still being more reliable and more predictable than other recently developed processes. Furthermore, the system and method is less complicated and more efficient than other systems and processes currently known. Furthermore still, the method includes spraying fluid onto a surface of the item to reduce edge heating.