The Mechanics of Making Ice Cream

Electric ice cream makers come in two main styles: canister-style and self-refrigerating. The former has a removable coolant-lined canister that must be frozen before use. Self-refrigerating machines are generally much pricier, with built-in compressors that chill the canisters so there’s no need for prefreezing.

All ice cream makers work in a similar fashion. First, you make a loose dairy or fruit base and pour it into the machine. Then, through a combination of cooling and constant-yet-gentle churning, the machines transform the base into a thick, creamy dessert. The churning incorporates a small amount of air that is crucial to a smooth, semisoft consistency—without the air, the bases would freeze into hard bricks. Once the base has thickened to the consistency of a milkshake or soft-serve ice cream, it is transferred to a clean container and placed in the freezer for a brief firming-up period. Working quickly is crucial when churning and transferring the dessert to minimize the formation of large ice crystals and prevent accidental thawing.

So, how do you achieve the effects without the ice cream machine? You need to aerate and chill the custard or puree without producing ice crystals. Adjusting the ingredients is one way: you can use invert sugars like corn syrup and additional fat to limit ice crystal formation. Incorporating air into the mix before freezing is another way: you can aerate the base through agitation with the blender, stand mixer, or food processor.