Ice-cream trucks, fast food chains, and dedicated specialty shops serve a lot of soft serve this time of year. The operator pulls a lever, and like magic, the frozen treat swirlingly extrudes into the waiting cone or cup. No backbreaking scoop work required. How does it work?
How Is Scoopable Ice Cream Made?
To understand soft serve, it helps to know how regular ice cream is made: A base of milk, cream, sugar, flavorings, and other optional ingredients is simultaneously frozen and churned, in a process that constantly agitates the mixture as it chills, with paddles or blades that scrape the icy walls of the freezing chamber.
Once the mixture gets down to about 20–25 degrees Fahrenheit, it’s removed from the churning chamber and packaged and placed in a regular freezer to bring it down to 0°F or below, which gives it that firm scoopability.
Sign up for the Cook's Insider newsletter
The latest recipes, tips, and tricks, plus behind-the-scenes stories from the Cook's Illustrated team.
How Is Soft Serve Made?
According to ice cream scientist H. Douglas Goff, “almost the only thing which differentiates hard frozen ice cream from soft serve, is the fact that soft serve is drawn into cones [when it is 20–25 degrees] rather than into packages for subsequent hardening.”
Just like regular ice cream, soft serve starts out with a base of milk, cream, and sugar, but it’s typically unflavored and (like most commercial ice cream) contains a small amount of added emulsifiers and stabilizers. These improve the texture and help it keep its shape on the cone, since it’s not served cold enough to stand up straight otherwise.
The churning and freezing process happens inside a specialized machine that holds a reservoir of this ready-to-freeze base just above freezing. As needed, the cold liquid base is automatically mixed with flavor and pumped through a slender cylinder that combines it with air while churning and freezing the mix to about 25 degrees. It is then extruded from the machine, ready to lick.
During the churning process, soft-serve ice cream sometimes is allowed to incorporate more air than scoopable ice cream, which has a number of potential advantages. It lightens the texture, which can be refreshing! It insulates the soft dessert from melting too fast. It saves costs for the retailer, since air is free. And it lowers the calories per serving, which is very often a selling point.
Is Soft Serve Real Ice Cream?
By law, ice cream must contain at least 10 percent milkfat. By that definition, some soft serve is ice cream, but the majority of commercial soft serve is formulated with less fat than that, most commonly around 5 percent, so technically it is classified as “light” ice cream.
What Is Frozen Custard?
Frozen custard, which can be made in either soft-serve or scoopable form, gets its special rich flavor and lush texture from the addition of egg yolks to the starting base mix.
What Is Frozen Yogurt?
Unlike ice cream and frozen custard, the United States does not have an official definition for frozen yogurt. In practice, it is a frozen dessert with tangy flavor. Most typically that tang comes from the inclusion of at least some yogurt, which is tangy due to lactic acid fermentation. But it’s also possible to make a frozen yogurt product using acidic flavor powders and no bacterial culture at all. Soft-serve frozen yogurt products are typically, like other soft serves, lower in fat than ice cream, and touted for their supposedly diet-friendly nature. The low-cal, flavor-powder products have given frozen yogurt something of a bad name, but it can be incredible. When I make frozen yogurt at home, I start with homemade yogurt, culture it with heavy cream and then flavor, sweeten, and churn it.