Contrary to what you may have heard, fat is good.
One of the biggest factors in ice cream’s texture is the amount of “butterfat” (the fatty part of milk) that it contains. If there’s not enough butterfat, the ice cream tends to taste icy and not very smooth—which is fine if you’re making a sherbet or a sorbet. On the other hand, if there’s too much butterfat, it starts to taste greasy like lard, and it sticks to the inside of your mouth. Or in other words, it has bad “mouth feel”.
Another big factor that controls the texture is the amount of air in the ice cream. Companies with big fancy machines can control the amount of air they introduce into the ice cream, and adjust the mouth feel that way as well. But since our home machines add a fairly fixed amount of air each time, our main method of controlling the texture is by controlling the butterfat content.
· Homemade ice cream recipes often contain about 19% butterfat. See my post about Making an Ice Cream Butterfat Calculator for more info.
· Super-premium ice cream contains about 14-16% butterfat.
· Frozen custard is similar to ice cream, and is defined by the same FDA regulation as ice cream. It also must contain at least 10% butterfat, but must also have at least 1.4% egg yolks. It’s made with a machine that adds less air so it tastes more dense, and it’s served fresh at a higher temperature so it’s usually softer.
· Gelato isn’t regulated but is usually about 3-8% butterfat and often contains more stabilizers to compensate for a lack of cream and eggs. And like frozen custard, it’s also made with less air, and served warmer, than ice cream.
· Ice Milk is about 3.5% butterfat, the same as whole milk.
· Sherbet is also defined by the same regulation as ice cream and must contain 1-2% butterfat.
· Sorbet usually contains no dairy at all, and is usually just frozen fruit juice, sugar, and water.
The percentages of butterfat listed above are by weight, not by volume. So if you took a gallon of 16% super-premium ice cream and pumped it full of enough air to make it into two gallons, it’d still be 16% butterfat by weight, but it’d taste entirely different (and terrible, probably). When you eat a super-cheap grocery store ice cream that tastes like you’re eating flavoured air, that’s pretty much what it is. They’ve put too much air into it, so they can sell more of it without actually adding more dairy ingredients. Of course, the opposite can happen as well. If there’s not enough air in the ice cream, it tastes too dense, almost like a frozen block of cream. There’s a fine line between too much or too little air, and too much or too little butterfat.
Gelato and frozen custard are usually sold fresh, meaning they’re not stored like ice cream in a deep-freeze until they harden. This is partly because the butterfat content is low enough that the water in the mix would freeze into larger crystals, making it taste icy.
By the way, ever wondered what 2% milk is two percent of? Well, it’s not 2% of the butterfat in whole milk, because that’d be 2% of 3.5%, or in other words, white water. It’s 2% total butterfat, just like whole milk is 3.5% total butterfat. 2% milk is about 5 grams of fat per cup (240 ml) compared to 8 grams per cup in whole milk. Drink up.