METHOD OF PASTEURIZING ALIMENTARY PRODUCTS IN MACHINES PROVIDED WITH GAS-COMPRESSION REFRIGERATING CIRCUITS
The circuit of a gas-compression refrigerating unit in ice-cream making machines and/or ice-cream mixture pasteurizing machines has inserted therein a by-pass circuit controlled by one or more switching valves. During the cycle of pasteurization and/or sterilization of the ice-cream mixture and of the elements of the machine contacting said mixture (either liquid or frozen), the hot refrigerant gas coming from the compressor is diverted through the evaporator (by-passing both the condenser and expansion valve) so as to heat to a sterilization temperature all the elements of the apparatus which usually are cooled by said evaporator. On completion of this pasteurization and/or sterilization cycle, said by-pass circuit in shut off and the refrigeration cycle is resumed by switching said valves, whereby the fluid refrigerant is circulated from the compressor to the condenser and expansion valves into the evaporator so as to refrigerate the elements that are in heat exchange relationship with said evaporator.