Ice cream machine

A domestic ice cream maker is a machine used to make small quantities of ice cream for personal consumption. Ice cream makers may prepare the mixture by employing the hand-cranking method or by employing an electric motor. The resulting preparation is often chilled through either pre-cooling the machine or by employing a machine that freezes the mixture.

An ice cream maker has to simultaneously freeze the mixture while churning it so as to aerate the mixture and avoid ice crystals. As a result, most ice creams are ready to consume immediately. However, those containing alcohol must often be chilled further to attain a firm consistency.

Some machines, such as certain lower-priced countertop models, require the resulting mixture to be frozen for additional time after churning is complete.

Around 1832, Augustus Jackson achieved fame for creating multiple ice cream recipes and pioneering a superior ice cream preparation technique and decoration.

In 1843, Nancy Johnson of Philadelphia received the first U.S. patent for a small-scale hand-cranked ice cream freezer. The ice cream freezer was a pewter cylinder.

These machines usually comprise an outer bowl, and a smaller inner bowl with a hand-cranked mechanism which turns a paddle, sometimes called a dasher, to stir the mixture. The outer bowl is filled with a freezing mixture of salt and ice. Adding salt to the ice causes freezing-point depression. As salt melts the ice, the heat of fusion allows the ice to absorb heat from the ice cream mixture, which freezes the ice cream.

This type of ice cream maker is inexpensive but can be inconvenient and messy since the ice and salt mixture produces salty water, which the ice cream maker must dispose of. The ice and salt mixture must be replenished to make a new batch of ice cream.

Some small manual units comprise a bowl with coolant filled hollow walls. These have a volume of approximately one pint (500ml). The paddle is often built into a plastic top. The mixture is poured into the frozen bowl and placed in a freezer. The paddles are hand-turned every ten minutes or so for a few hours until reaching the desired consistency and flavor. Nancy Johnson invented the first hand-cranked model in 1843. She then sold the patent to William Young, who marketed the machine as the "Johnson Patent Ice-Cream Freezer."

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Wikipedia