The baking fat smackdown: Which ones you should use for what recipes
In the wide interweb world of food writing, fads come and go. They help us discover new foods and rediscover old favorites. But when it comes to baking, the type of fat you use shouldn't be based on trends but on your desired outcome. Understanding how those fats differ is how you make sure every pie, cake and loaf of bread turns out exactly how you want it.
The science of fat in baking
While I do think "baking is a science" is an excuse celebrity chefs use for not spending enough time practicing a simple yeast bread recipe, the fact remains that it's at least as much science as it is art. And understanding that science makes you better at the art.
No matter what kind of fat you use, fats serve an important function in baking. They mimic moisture without evaporating like water would, provide tenderness by weakening the gluten, aid in the baking process by ensuring heat is more evenly distributed and enable browning by attracting the heat without evaporating.
When it comes to fat, it's important to follow instructions about temperature. Whether it's melted, room temperature or cold does affect its interaction with other ingredients.
All fats do this slightly differently, which is why it's important to understand what each fat does. Before you know it, you'll be substituting fats to customize your recipes exactly the way you want them.
Butter: All about flavor
Butter is used for its flavor, as a general rule. Its tenderizing ability is good but not the best. When used to make pies, it's somewhat flaky but not the best, and when used to make cookies, it does allow some spreading, though it's far from the worst. But you really can taste the difference, and that's where butter usually wins.
Note that European butter has slightly more fat (and technically flavor) than American butter has. While the difference seems negligible, many bakers (this one included) swear by its superiority. Butter comes in salted and unsalted varieties. In general, you should use unsalted unless a recipe specifically calls for salted or cut back on the amount of salt you use. It should also generally be used at room temperature unless the recipe specifies cold or melted butter. Note that clarified butter is best left for non-bake recipes, as the act of clarifying ruins the flavor and makes cakes dense and cookies more cake-like.
Margarine: Not much good for anything
Margarine seems to have a lot of properties similar to butter, but they're far from interchangeable. Margarine's higher water content leads to less flavor, terrible tenderness, lots of spreading for cookies and negligible flakiness for pie crusts. There's also no such thing as unsalted margarine.
When it comes to baking, about the only thing it's good for is basting the top or helping to reduce sticking. This applies even more to those heart-healthy spreads. If you're trying to save fat, opt for a recipe calling for fruit purées.
Shortening: Tender cakes and flaky pie crusts
Shortening is essentially flavorless in small quantities or in recipes that have a lot of punch from highly flavorful ingredients, but it makes up for that by making utterly tender cakes and quick breads and the flakiest of pie crusts. It should be avoided if butter's flavor would be strong in a recipe (like buttercream frosting), as it does have a rather unpleasant flavor (like used fryer oil). If you crave the flavor of butter but the benefits of shortening, you can always use half shortening and half butter. The one thing shortening doesn't do well is cookies. While it doesn't allow too much spread, the flavor is just obvious… one you'd associate with cheap grocery store cookies.
Lard: Even better than shortening
Lard has a bad rap, but it's actually not nearly as unhealthy as people have been led to believe and is actually the fat of choice for many nutritionists. That said, it's just as good as shortening at tenderizing cakes, makes cookies that spread nary a bit and makes the most tender, flaky pie crust you've ever enjoyed. While it's near identical to shortening in its effects on baked goods, it doesn't have the sort of fake flavor as its vegetable fat counterpart, making it a good alternative if the flavor of shortening just turns you off.
Vegetable oil: Denser cakes and quick breads
Whether or not oil has much flavor depends on what you use. Olive oil has some, but generic vegetable oil has none. Oil adds denseness to cakes, making it some people's choice of fat for brownies and certain quick breads (or really, any cake you prefer a denser texture for). It does make cookies rather cake-like, though.
Coconut oil: Add some flavor to cakes and quick breads
Much like butter, coconut oil has a lot of flavor, though its flavor profile is different. And bear in mind that unrefined coconut oil has a lot more flavor than refined has. In fact, if you're substituting with coconut oil, you may want to reduce the sugar by a third or so, since coconut oil has a natural sweetness. If you're substituting liquid fat with it, it needs to be melted to use it. But since coconut oil is solid at room temp, you can use it as is when subbing for solid fats. Try it in brownies and sweet quick breads for a touch of coconut flavor.