Learn the science behind:
It smells nutty, almost vanilla-like, buttery, and just generally delicious: brown (or burnt) butter. It requires only one ingredient and just a little bit of patience. That simple process unleashes a series of chemical reactions which all contribute to the amazing flavor and smell of brown butter. It’s pure chemistry.
But what do you then do with that brown butter? Eating it as is, isn’t the best experience. Here, we’ll be using it to make delicious cookies. Combining chemistry + great tasting food is the best, isn’t it?
What is brown butter?
Brown butter is a very good description of what it is: butter that has been browned. That doesn’t mean all the butter will have actually turned brown. Instead, the majority of the butter is still yellowish, but, at the bottom, you’ll find browned pieces. The brown butter hasn’t just changed color, the smell is also noticeably different from that of regular butter. It smells nutty, caramel, maybe vanilla-like. The flavor profile is actually quite complex!
We’ve written about brown butter extensively. Want to know exactly what happens when making it? Do a deep dive on brown butter.
Brown butter vs. Butter = Missing water
Aside from the aromas that are formed when making brown butter, another crucial change takes place: water evaporates.
Butter isn’t a pure fat like olive oil or soybean oil are. Instead, butter is an emulsion of water in fat. Water droplets are dispersed throughout the fat. It gives butter a unique role in foods like cookies, it doesn’t just add fat, but also moisture. However, when browning butter, all that water will evaporate. It’s why you also end up with significantly less brown butter than what you started out with in butter weight.
When browning butter you lose about 15-20% of the initial weight. This is due to water evaporating.
Why use brown butter in cookies?
Just about all cookies will contain some sort of fat. Fat is important for flavor, but also texture and mouthfeel. A cookie without fat would be more like a cracker than a cookie. Fat also helps achieve a good cookie dough consistency and helps ensure the cookie doesn’t turn dry.
Fats and oils are all made up of the same type of molecules: triglycerides. Sunflower oil, olive oil, butter fat, lard, they are all a mix of triglycerides. They differ in the exact types of triglycerides, which is why some fats are liquid are room temperature whereas others are solid. Fats that are liquid at room temperature are generally called oils. They can be used in cookies, but tend to make quite an unstable dough. The oil can easily leach out of the dough, giving an unappetizing cookie. It’s why a lot of cookies often contain at least some fats that are solid at room temperature.
Brown butter can be used in these instances. But it’s just one reason for using it.
A lot of the more refined oils, such as soybean or safflower oil have been refined quite extensively. During this process, a lot of the minor molecules are taken out. This helps to preserve the oils so they don’t oxidize and develop off-flavors. However, it also means these oils are pretty bland. They don’t really taste like anything specific.
Enter: brown butter. Brown butter is possibly the opposite of being refined. It is full of ‘contaminants’ that will likely decrease the shelf life (best to use it within a couple of days after making if you’re not taking any steps to prevent it from oxidizing). But, these are full of flavor. So, when using brown butter in a cookie recipe, you’ll add a ton of depth of flavor to make your cookies pop.
How to use brown butter in cookies?
Since brown butter still contains the same fats that the butter you started out with contains, it will behave in a very similar manner. The only tweak you should make to your recipes is to account for the loss of moisture. As such, if you’re replacing 100g of regular butter, you should replace it with 85g of brown butter and 15g of water. This should give a cookie dough that’s very similar to one using just butter, but with more flavor (and a brown color!).
Dufossé, Laurent & Latrasse, A. & Spinnler, Henry-Eric. (1994). Importance of Lactones in Food Flavors – Structure, Distribution, Sensory Properties and Biosynthesis. Sciences Des Aliments. 14. 17-50. link
Patrick Fox, Advanced Dairy Chemistry volume 3: Lactose, water, salts and vitamins, 2nd edition, p.420, link
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Gerda Urbach, Butter flavour in food systems, Food Research Quarterly Volume 51, 1991, link