An in-shell egg pasteurization process includes, in a temperature-raising stage (12), raising the temperature of yolk of a plurality of in-shell eggs (40), simultaneously and at least predominantly by means of microwave radiation, to a pasteurization temperature, the temperature-raising stage (12) including a plurality of elongate or longitudinally extending microwave cavities that are isolated from one another so that microwaves fed into an elongate or longitudinally extending microwave cavity do not leak into any other elongate or longitudinally extending microwave cavity. The in-shell eggs (40) are displaced along the lengths of the elongate or longitudinally extending microwave cavities whilst being irradiated with microwaves. In a pasteurization stage (14), the raised temperatures of the in-shell eggs (40) are maintained for a pasteurization time sufficient to pasteurize the in-shell eggs (40).
