An ice cream machine turns a custard-like mixture into a frozen dessert using a chilled central canister, a churn and a drum that holds a freezing agent. Rock salt combined with ice is the traditional agent. Ice cream machines can also be used to make sorbets, gelatos and sherbets.
The central canister holds the mixture and sits inside the drum. The rock salt and ice mixture is packed between the outside of the canister and the inside of the drum. The churn, either hand-cranked or electric, continuously whips the mixture until it chills and thickens. The rock salt-ice combination is periodically replaced to keep the mixture cold. The result is a soft-serve ice cream, which can be eaten as is or put in the freezer to harden.
Some electric models use a double-insulated freezer bowl, which eliminates the need for the ice. The bowl needs frozen ahead of time, as does the ice cream mix. Another option on some models is the gelato paddle. Included along with a regular ice cream paddle, the gelato version incorporates less air into the mixture, creating a denser desert.
Gelato is an Italian creation that has less fat than ice cream. Sorbet, or sorbetto, has no dairy products. Instead, the dessert is made with pureed fruit, juices and honey. Sherbet combines dairy products with fruit purees and juice. Recipes suitable for home ice cream makers are available for all of these desserts.