The Science Behind Your Favorite Donuts— Cake, Raised & Baked Donuts
It's hard to find someone who doesn't love a good donut (though I know you're out there). But when it comes to picking a favorite, everyone's got their preference. Whether you're into dense, crumbly cake donuts, light and airy raised donuts, or the softer baked variety, there's a science behind why each one tastes and feels so different. Let's dive into the science behind what makes each type of donut unique.
What Are Cake Donuts?
Cake donuts are little cakes shaped like donuts. They usually start with a thick flour, sugar, eggs, and milk batter. When fried, they develop a dense and crumbly texture with a crispy exterior.
Why Cake Donuts Taste Better
When oil gets hot, it starts to break down, especially when steam from the food mixes with it. This breakdown causes the oil to split into various components, including diacylglycerides, which can further break down into monoglycerides, glycerol, and fatty acids. These fatty acids carry unique flavors that get absorbed by both the food and the oil, giving fried donuts that irresistible taste. However, if too many of these flavor compounds build up, the food can taste off or overly heavy.
The Science Behind Cake Donuts
Since donuts are in direct contact with hot oil - frying cake donuts involves submerging the batter in hot oil, typically heated between 350 - 375°F (177 - 191°C) - they cook quickly, triggering a more intense Maillard reaction—a chemical reaction between reducing sugars and amino acids or proteins that results in a deep, complex flavor and a golden-brown crust.
As the donuts fry, water inside the dough evaporates, which allows oil to be absorbed, creating more flavor. However, the crust formed during frying acts as a barrier, limiting the amount of oil that enters the donut and preventing the interior from becoming overly greasy or overcooked. Because of the loss of moisture, the shelf life of a cake donut is shorter as it dries out quickly versus an oven-baked donut.
This process, combined with how the oil breaks down, results in a dense and crumbly donut on the inside with a deliciously crispy crust. The texture is a bit drier than traditional cake, with a firm exterior that makes cake donuts perfect for dunking in coffee or milk.
What are Raised (Yeast) Donuts?
Raised or yeast donuts start with a dough similar to cake donuts, using flour, sugar, eggs, and milk. But instead of relying on baking powder, yeast donuts depend on yeast for leavening. This process takes a bit more time, as the dough needs to be kneaded, shaped, and given time to rise as the yeast ferments. Once the dough has risen, it's shaped into donuts and fried perfectly.
Why are Raised Donuts So Light and Fluffy?
Yeast fermentation is critical to the airy texture of raised donuts. As the yeast feeds on the sugars in the dough, it produces carbon dioxide and alcohol. The carbon dioxide forms air pockets, making the donuts light and fluffy, while the alcohol evaporates during frying, leaving a subtle, slightly tangy flavor behind.
Kneading the dough develops gluten, a network of proteins that gives the dough its elasticity and structure. This is why raised donuts have a soft, airy, chewy texture similar to bread, unlike the denser texture of cake donuts.
When these donuts hit the hot oil, the Maillard reaction takes over, browning the exterior and adding a satisfying crispness while keeping the interior fluffy and light.
Why Do Yeast Donuts Feel Lighter and Less Greasy Than Cake?
Yeast donuts are less greasy and dense due to the difference in leavening agents and dough structure. The carbon dioxide produced by yeast creates a more open structure, allowing the dough to expand more during frying and absorb less oil. In contrast, cake donuts, which use baking powder or baking soda, rise quickly but produce a denser texture that tends to absorb more oil. Additionally, the softer, more elastic dough of yeast donuts cooks faster and more evenly, which helps seal the surface quickly and reduces oil absorption. This is why yeast donuts feel lighter, less greasy, and have that incredible, airy texture.
Raised donuts have a light, sweet flavor with a hint of yeast, giving them a slightly tangy taste. They are often coated with glaze or sugar, offering extra sweetness. Their texture is closest to bread—light, airy, and fluffy, with a chewy bite. Thanks to the air pockets created by the yeast, they feel softer and lighter than cake donuts.
What are Baked Donuts?
Baked donuts are an outlier in the donut world. Unlike their fried counterparts, baked donuts can be made with a cake-like batter or a yeast-based dough. The ingredients are similar to those used in cake or raised donuts, depending on the recipe, but the baking process sets them apart.
Because they are baked, the Maillard reaction, the chemical reaction responsible for the golden crust, will be less intense than in frying, as heat transfer is slower and more gradual in an oven. This means moisture stays trapped in the batter as it doesn’t escape as quickly as in frying. The trapped steam helps the donuts stay moist, giving them a denser, softer texture that is not crispy and a more subtle flavor with a longer shelf life. This results in a donut with a smoother, less crispy exterior on baked donuts.
Why are Baked Donuts A Healthier Alternative?
Baking donuts instead of frying them results in a different texture. The Maillard reaction responsible for the golden crust will be less intense than in frying, as heat transfer is slower and more gradual in an oven. This means moisture stays trapped in the batter as it doesn’t escape as quickly as in frying. The trapped steam helps the donuts stay moist, giving them a denser, softer texture that is not crispy and a more subtle flavor with a longer shelf life. This results in a donut with a smoother, softer, less crispy exterior and more subtle flavor.
In Summary
Each type of donut—cake, raised, and baked—brings something different to the table, and it’s all thanks to the science behind how they’re made. Cake donuts are dense and crumbly with a crispy crust, thanks to the combination of baking powder and frying. Raised donuts are light, airy, and chewy, with yeast fermentation playing a pivotal role in their texture. Whether cake-like or yeast-based, baked donuts offer a softer, less greasy alternative.
SOURCES
Functional Dietary Lipids Parkash Kochhar
Batters and Breading in Food Processing, American Associate of Cereal Chemists International,
R. Paul Singh, Sukumar Debnath
Deep Frying (Second Edition), Chemistry, Nutrition, and Practical Applications, Jean-Louis Sébédio, Pierre Juaneda
