Few things make me happier than dunking a couple shots of whiskey into my homemade ice cream base. Few things make for tastier ice cream, too—just a tablespoon or two of hooch brings incredible complexity and depth to a scoop, be it the most flavorful vanilla bean you'll ever taste or an Old Fashioned in frozen, creamy form.
Alcohol's low freezing point also makes for softer, more scoopable ice cream, a handy way to make a stubborn ice cream or sorbet recipe easier on the arm and more melty in your mouth. But when it comes to ice cream misconceptions and mythology, no ingredient is more misunderstood than booze. So let's get the main point out of the way.
This statement is true: Adding alcohol to ice cream makes it softer and easier to scoop.
This statement is false: Alcohol makes ice cream less icy.
Knowing the distinction between the two is the difference between making soft, creamy, delightfully boozy ice cream and harsh-tasting, icy slush.
The Powers of Booze
The freezing point of water is 32°F (that'd be 0°C for those of you who don't use the wacky units we cling to here in the U.S.). For pure alcohol—ethanol—that number is -173°F. 80 proof vodka freezes around -16°F; balmy by comparison, but still way colder than water. The point behind these numbers: the more alcohol you add to ice cream, the lower you make its freezing point.
Even in a fully churned ice cream, not all the liquid has been frozen solid. Dissolved sugar and emulsified fat and protein create a soup of super-concentrated syrup surrounding millions of tiny ice crystals and air bubbles. By adding alcohol to ice cream, you increase that proportion of liquid syrup to solid fat and ice, which makes for a softer scoop.
If you're dealing with a low-butterfat ice cream base or a sorbet base that calls for a lot of water, alcohol will indeed make your ice cream softer and easier to scoop. It'll also add a blast of flavor that blooms once diluted in a base. Vanilla extract, after all, is just vanilla-flavored vodka. With dark spirits like whiskey, rum, and brandy, the extract's honeyed, vanilla flavors get amplified by even more complex compounds thanks to wood barrel aging. Lighter spirits like gin, tequila, and liqueurs are concentrated bombs of botanicals, herbs, and spices. Whether you're making a cocktail-inspired ice cream or merely one that benefits from a jolt a hooch, just a tablespoon of two of alcohol is powerful stuff.
The Danger of Overdoing It
The problem of using alcohol in ice cream is the same as using it anywhere: add too much and you find yourself with a smelly, melty puddle on the floor. For a standard quart of ice cream base, adding more than five or six tablespoons of 80 proof liquor leads to an ice cream that'll never freeze hard enough to scoop. The ice cream will also taste so viciously boozy as to be unpalatable.
There are dangers even with more moderate amounts. Lowering an ice cream's freezing point means you also lower its melting point, so a boozy ice cream will melt faster in your mouth, in a bowl, and even in a freezer than a non-boozy one. Freezers cycle on and off, and over time, even with ideal storage, ice cream will melt and refreeze in your freezer, slowly turning icier with every cycle. By lowering ice cream's melting point, you make a less stable ice cream with more pronounced ice crystals.
Unlike ice cream stabilizer, booze adds no body or creaminess to ice cream, only softness. That's why, when people ask for ways to make their ice cream softer, booze is the last solution I recommend. If controlling texture is your main goal, try upping your butterfat or egg content, or try a more viscous sweetener.
The Real Rules of Boozy Ice Cream
When I develop a boozy ice cream recipe, I think of it like a cocktail. You have a set number of parts to play with, and both the strength and flavor of your recipe depend on how you use those parts.
Let's use five tablespoons of liquor as our boozy maximum. One or two tablespoons of a spirit adds a hint of something extra. Three or four and the spirit blooms, adding a noticeable kick to the ice cream. Five tablespoons or more of any one spirit may be overkill in a mild ice cream base, but four tablespoons of rye and one of sweet vermouth will make a killer Manhattan ice cream. Or pair three to four tablespoons of tequila with one of Cointreau and brighten the whole thing with a shower of lime zest for a killer frozen margarita.
Liqueur and Fortified Wine
For liqueurs and fortified wines in the 20 to 40 proof range, you can get away with adding more than five tablespoons and still churning freezable ice cream, but the flavor may be too strong. Three tablespoons of Campari is plenty in this raspberry frozen yogurt. When it comes to bitters, a few dashes is all you need.
Beer and Wine
Beer and wine are trickier to codify. With alcohol content anywhere from four percent up into double digits, different beers and wines will behave differently in ice cream. In general though, with most beer- or wine-forward ice cream, it's worth reducing the liquid over low heat to lower its water content and concentrate its flavor.
Just how much depends on your recipe; in my pear, ginger, and riesling sorbet, wine acts not just as a flavoring but also a cooking medium for the pear and gingerd. This mulled wine ice cream, on the other hand, calls for cooking two cups of wine down to a thick, viscous syrup before adding it to dairy, which also drives off most (but not all) of its alcohol.
Reducing beer and wine makes for less watery ice cream, but it also mutes the drinks' flavor. If you want to preserve the bright kiss of citrus in a hoppy IPA or the acidity in Champagne, set some aside before reducing, and then when you've finished making your ice cream base, add it, a tablespoon at a time, until you get the fresh flavor you're looking for.
Beyond these basic rules, how you booze up your ice cream is completely up to you. Beer, wine, and spirits are the fastest, easiest way to add layers of complex flavor to your ice cream. Just don't except them to make your ice cream any creamier.