A system for pasteurizing animal food, comprising a pasteurizing unit and a cooling unit designed as a heat exchanger (3 or 3') is disclosed. The height (H) of the heat exchanger (3 or 3') is a multiple of the maximum width (D) thereof. A pipe is provided inside the heat exchanger (3 or 3') as a cooling serpentine (6) which extends nearly along the entire height (H) of the heat exchanger (3 or 3')