During the warm summer months, gadget retailers trot out their latest colorful, charmingly designed home ice cream makers. The price point is usually around $40-$50, and they consist of three main parts: a tub or ring you put in the freezer, some kind of paddle for churning, and a motor housing.
Unfortunately, the finished product you get from these machines is usually somewhat sticky from the standpoint of texture and "muddy" flavor-wise. If you're looking for a super clean, crisp peach or raspberry fruit flavor, for example, don't bother with these devices. Here's why.
Check out the recipes that come in the box with one of these inexpensive home machines. You'll find titles like "French Vanilla" or "Chocolate Decadence." While many of the ingredients may vary, they all typically call for egg yolks, or start with a base that contains them (which explains these purple references to richness). Unfortunately, egg yolks also contribute egginess, which when paired with vegetal and delicate flavors, can be a questionable virtue. So why do we need egg yolks, anyway?
Creamy, Not Crummy
From a “what’s in it” standpoint, ice cream is simple: cream, sugar, and flavorings (in home recipes, those ever-present egg yolks, too). To some degree, however, the ingredients aren’t really the most important thing; it's how they hold themselves together when frozen and churned. The spinning blade and freezing cold transform the structure of the parts into something that's truly noble: smooth, melting, and velvety. And as many of us are painfully aware, fat delivers flavor very effectively. Whether it's in Doritos or ice cream, the fat makes it good, and ice cream has plenty of it: about 10-20% milkfat.
What's Up in the Tub?
Technically, ice cream is both an emulsion (things that don't want to hang together are cajoled into it, such as in creamy salad dressings or plain milk) and a foam (things that contain tiny bubbles trapped in a membrane that won't let them easily escape, such as in whipped cream and beaten egg whites). To you and me, this boils down to a luxurious mouth feel, a unique texture that has body yet melts away perfectly, and a wallop of flavor on your milkfat-lubricated palette.
The presence of the sugar and salts naturally occurring in the cream mixture makes it impossible for all of its water to freeze, just like salt on the driveway. Some of the water in ice cream remains liquid, and the fat from the cream, lubricated by the liquid water, jostled by ice crystals, and beaten mercilessly by the churning blade forms a network of loosely confederated fat droplets. This network is key: it creates the structure of the ice cream, and provides the to-die-for texture.
Most homemade ice cream recipes start with a base that calls for cooking egg yolks with cream at very low heat to create a thin custard. After being cooled to refrigerator temperature, this custard gets churned. Cooking is advised to sterilize the raw egg, but if you buy pasteurized eggs, this step really isn't necessary.
Fat and water magnetically repel each other in their natural state (think oil and water). However, when egg yolk is added, it acts like free cocktails at a work party, allowing the fat and water to sit next to each other without undue stress. Without this ambassador of molecular peace, all kinds of havoc can take place, including separation of the ingredients and poor texture. The problem, of course, is that egg yolks also contribute plenty of eggy goodness (or badness, depending on your tastes) and additional fat.
Getting Around the Eggy?
In commercial ice cream, the job of emulsifying is entrusted to chemicals like Polysorbate 80, which contributes little or no flavor. There's also quite a bit that can be done from an industrial process perspective, such as super-fast and super-cold freezing to regulate the formation of ice crystals. These methods simply aren’t available in the average home, although some machines, such as this Cuisinart model, do a better, faster job of freezing (they cost around $250) than the usual sort.
The bottom line? If you're looking for something clean on the palette to carry the fruit, tea, or other delicate ice cream flavors you've been dying to make, you might want to look at something more expensive by way of an ice cream maker than the typical summer special unit. If you like French vanilla, caramel, chocolate, or other flavors that harmonize with eggs more cozily, go ahead and get that home ice cream maker. They're also good for sorbets and ices.