Why Adding Butter To Your Cakes Could Be A Moisture Mistake

Butter makes everything better, right? From decadent pastries to delicious, essential sauces, it's the key to many restaurants' most flavorful dishes, which also happens to be why chefs often use butter to cook steak. But there are certain situations in which butter can work at cross purposes to your desired outcome. Baking the most succulent cakes is one such instance, according to Kierin Baldwin, chef-instructor of Pastry & Baking Arts at the New York City campus of the Institute of Culinary Education.

It turns out that when it comes to cakes, oil is actually a better choice than butter due to the moisture makeup of each source of fat. "Oil is 100% fat, whereas butter contains about 16–20% water, depending on the brand and type," Baldwin said. That water content can make a huge difference to the ultimate texture of the cake. "Fat contributes to tenderness because it inhibits gluten formation and doesn't provide leavening the way water does. It also helps starches and proteins retain moisture by shielding them from drying out," Baldwin explained. "In general, the more fluid a fat is, the more effectively it preserves moisture in a baked item."

You can use the knowledge of the respective fat content to swap oil for butter in recipes to enhance their moisture and crumb texture. Since butter is up to 20% water, one of many useful hacks for a moist cake is to add an amount of oil equivalent to 80% of the butter the recipe calls for, and make up the rest with milk. 

Having said all that, there is a clear benefit to using butter in cakes, which is its role in enhancing the rich taste. So, what should you do if you don't want to sacrifice the flavor but still want the added moisture of using oil? It turns out, in this one particular instance, you can have your cake and eat it, too.

"Hybrid cakes are your answer," said Kierin Baldwin. "You can make a creamed butter method cake and add a small amount of oil at the end of the creaming process." By incorporating both butter and oil, you're able to get the benefits of both fats without having to sacrifice anything. This isn't only true for cakes. Mixing oil and butter can yield the perfect French toast as well.

Different recipes will call for different ratios of butter to oil, Baldwin noted, but this trick yields great results, not just in the short term but also in terms of extending its shelf life. The addition of oil to the butter helps the cake maintain its moisture for longer. Baldwin also had one last trick up her sleeve: "To lighten it up even more, fold in some meringue at the end for added leavening," she said.