Batch pasteurizers are disclosed for processing milk, colostrum and other dairy products. The pasteurizers comprise inner drums to contain the processed liquid, an outer drum surrounding same and providing an annular space for retaining a heating fluid (heated by an electrical heater), a helical coil to carry cooling fluid through the heating fluid, a motorized pump or impeller to agitate the treated liquid to optimize heat transfer, and a control system to switch the heater on and off, actuate cooling liquid flow and optionally, at least partially drain the heating fluid to provide a temperature/time profile and close temperature tolerance, all of which produce pasteurized products with adequate levels of immunoglobulins to provide newborn animals with sufficient immune function.