One of the joys of making ice cream at home is having the freedom to change ingredients and personalize a recipe to suit my mood. But no matter what my flavor of the week is, I always aim for ice cream with a creamy, smooth texture, a soft consistency, and a full body that’s neither too airy nor too dense. To get this wonderful mouth-feel, it helps to know how different ingredients and techniques affect texture and consistency.
Dairy products improve smoothness
When an ice-cream mixture gets poured into a machine and stirred, some of the liquid freezes into pure ice crystals while some of it remains liquid. The goal is to keep these developing ice crystals small and plentiful, so you end up with a smooth, creamy texture. If they grow too large, the resulting ice cream is coarse and icy.
Cream and milk promote smoothness and lightness. The high fat content in heavy cream and whipping cream coats ice crystals, preventing them from enlarging. It also acts as a lubricant between crystals, making even ice cream with larger crystals feel smooth on the tongue. Cream is also excellent at trapping and holding air when the mixture is stirred and frozen, which gives the ice cream more body.
As important as cream is to great ice cream, however, it’s possible to overdo it. If you’ve ever had ice cream that seemed to coat your mouth with fat, it probably had too much cream. The solution is to reduce the cream and add a lower-fat dairy product, such as half-and-half or milk.
Milk lightens ice cream because of its proteins, which are superior to fat at trapping air (though not as good at holding it). This, by the way, is why skim milk foams up better than whole milk for cappuccino. Milk also contributes to smoothness, thanks to its high concentration of milk solids (such as calcium salts and lactose), which are even more effective than fat at controlling crystal size.
Use condensed, evaporated, or powdered dry milk in moderate amounts. Like milk, these ingredients have lots of milk solids, so ice crystals stay small. But they’re also brimming with lactose (milk sugar), which makes them useful in another way. Lactose, like any sugar, lowers the freezing point of ice-cream mixtures. That means more of the mixture stays liquid at freezer temperature and the ice cream will be softer. But beware, if there’s too much of these products, lactose crystals will form and you’ll end up with a sandy-textured ice cream. You’ll notice that Jim Peyton’s ice creams on contain some evaporated milk (as well as cream and milk)—enough to make the ice creams very smooth and soft, but not enough to make them gritty.
Adding fruit preserves is a great idea. They have concentrated flavor plus a small amount of pectin, which keeps ice crystals small and improves creaminess. Preserves can be swapped out tablespoon for tablespoon with sugar.
Egg yolks, those great emulsifiers, will also contribute silky smoothness. For flavor, I always add a small amount of salt (about 1/8 teaspoon). It enhances both the perception of sweetness and the flavor of the ice cream.
Sugar and alcohol make ice cream softer
Sugar makes ice cream softer because it lowers the freezing point of a liquid. For an ice cream that can be scooped right out of the freezer, you need just the right amount of sugar—too little and the ice cream is as hard as a brick, too much and you have mush. If you find that your favorite ice cream recipe is brick-hard and nearly impossible to scoop, try adding more sugar next time. Or try replacing some of the sugar with honey. Because honey consists of sugars with smaller molecules than those of table sugar, it’s more than twice as effective at lowering the freezing point as table sugar. Harold McGee, a food scientist, recommends substituting 1 Tbs. of honey for 2-1/2 Tbs. of sugar in ice cream.
Adding a liqueur or wine to an ice-cream mixture will make it softer because alcohol, like sugar, lowers the freezing point of a liquid. If you like the firmness of a particular recipe but want to add a liqueur for flavor, you might counter the addition of alcohol by cutting back on the sugar. Liqueur is preferable to wine because, at freezer temperature, a wine’s flavor would be muted.