A specialty type of refrigeration system found in some food service businesses is the soft-serve ice cream freezer. These systems are designed to inject an ice cream mix with the correct amount of air, and freeze the mixture to its specific consistency or temperature.
The basic system consists of a hopper, mix feed system, beater, and freezing cylinder. The hopper is a refrigerated holding tank for the ice cream mix. It’s designed to maintain the mix at a safe storage temperature. Connected to the hopper is the mix injector. As needed, the mix will be injected into the freezing cylinder. Air, called “overrun,” must be added to the mix. This is essential to the consistency of the product. Most machines have an adjustment on the mix feed system to adjust the amount of overrun. Some machines have a fixed overrun, set at the factory, for the particular mix being handled.