The Scientist’s Guide to Donuts

I love donuts (doughnuts?) but to be honest I didn’t really know much about them and had definitely never made them, personally. So I decided to take a stab at it using different cooking methods and share my learnings with you, for science (and fun).

Here I am enjoying the delicious “K-Stater” donut at Varsity Donuts

As someone with a degree in Nutrition (and a sweet tooth), I know donuts aren’t good for me. And they’re definitely not an ideal way to start your morning. (I’d recommend something with protein to help you feel full until lunch) But there’s something about them that I just can’t resist every once in a while. The devil on my shoulder urges, “Have another,” while the angel on the other side is angrily reminding me of all the sugar and lack of nutrients. However, donuts can be a perfect way to indulge (sparingly) on special occasions. I love pastries, bright colors, and unique flavor combinations, so donuts are the perfect way to combine each of these interests for a special treat.

Note: I invested in a new camera to practice my food photography, so this post will be very visual. Hope you enjoy!

Doughnut vs. Donut

The first thing to clear up is the spelling. Now I know when you’re about to indulge in a hot do(ugh)nut the last thing on your mind is how it’s spelled, but it’s always been a mystery to me. So, here it is. According to Serious Eats, the original spelling of the treat was “doughnut.” In the 1920’s it was modified to “donut” in order to simplify pronunciation and help businessmen selling donut equipment outside of the US. Not exactly the most interesting story, but now we know! Personally, I prefer the simpler version, so I’ll use it here.

Types of Donuts

There are two main categories of donuts: the yeast donut and the cake donut. Within these two types, there are endless variations of shape and flavor, from the traditional glazed donut to cider donuts to crullers.

Yeast donuts are leavened with yeast (shocker!), and are light and airy. Cake donuts are chemically leavened using baking powder or baking soda. These donuts have a more dense, chewy, cake-like crumb. These donuts are often baked, as shown here, but may also be fried.

I am definitely partial to the frosted yeast donut. But after making them myself, wow, was it a lot of work! The cake donuts are much quicker and easier.

Crumb anatomy of a yeast versus cake donut. You can see the structure is less aerated in the cake donut
Frosted yeast donut and apple cider cake donut

Making the Dough(nuts)

I chose a recipe by the Pioneer Woman/Bless This Mess for my yeast donuts and a recipe from Nordic Ware for the cake donuts.

I prepared the yeast donut dough the day before so it could chill and be easier to work with. I followed the directions as written, and found this to be the easiest step in the process.

The cake donuts have the benefit of using chemical leavening to leaven the batter, so this dough takes significantly less time. I made this dough and baked it while the other doughnuts were proofing and frying.

Follow along below to see the steps in the process to make yeast donuts:

After mixing, the yeast dough is verry sticky
The secret to rolling out and cutting donuts: chilled dough. Place it in the fridge overnight to allow the dough to become much easier to work with.
Roll the dough to about 1/2″ thickness
Use a donut cutter or cookie cutter to cut the circles and place onto a greased baking sheet. Shout out to my boyfriend who makes a great donut cutter and hand model 🙂
The donut cutter I used was 2.5 inches in diameter
Allow the donuts to rise until they have doubled in size, about 1 hour
That’s the yeast in action!


Having never made donuts before I decided to make this into a fun little experiment. I wanted to understand the difference between cake and yeast donuts, but I also wanted to experiment with how the flavor and texture would change when they were cooked. So, I air fried, deep fried, and baked.

Science of Cooking

Donuts are traditionally a fried product, but may also be baked. Air frying is a newer technique that uses little to no oil to cook food, but still gives the characteristic crispy outside, soft inside. If you haven’t tried it yet, I’d recommend it!

So, how exactly do these different heating methods compare? Let’s take a look.

Here’s where the donut hole comes in. The longer something is fried, the more moisture is lost. So, complete cooking of the center of the donut would significantly change its characteristics.

Convection is the transfer of heat from a fluid (liquid or air) to a solid (the donut). Oil temperature is another important factor. Be sure your oil is at 375 F BEFORE you start frying. The longer it takes to fry your product, the more oil is absorbed

The air fryer is similar to the deep fryer but uses forced hot air to transfer heat, rather than oil, thus leading to a crispy surface, . In this way it is more like a powerful, mini convection oven. You may use a small amount of oil or no oil in the air fryer to reduce your fat intake. I sprayed the donuts with a bit of cooking spray before placing them in the air fryer, so very little fat was used.

Each of these operations serve to transform dough into an edible product:

  • Starches from the flour gelatinize
  • Proteins denature (break down)
  • The Maillard reaction (between proteins and sugars) leads to the characteristic surface browning
  • Water activity (the free water available for microbial reactions, NOT the same as moisture) is reduced, thus preserving the product
  • Microorganisms present in the dough are killed
  • The product is now delicious – crispy exterior and moist interior

The Results Are In

To no surprise, the deep-frying process resulted in the most characteristic donut flavor and texture. You can see below it has a crisp, golden crust and light, airy crumb. Deep frying leads to uniform heat transfer because all surfaces of the product are being heated at once. When baking, there is less uniformity due to location of heat source, the need to flip, air movement, etc.

The air fried donuts were similarly golden and crisp. They had a great flavor and similar texture to the deep fried sample. I would recommend air frying as a great way to make delicious donuts while reducing your fat intake.

The baked yeast donuts turned into more of a biscuit. While still delicious, definitely not what we were going for! The different modes of heat transfer and the lower temperature, longer cooking time made a big difference. You can see the inside crumb looks similar to the other two samples, but there are large differences in surface texture.

Yeast donuts. Left to right: air fried, deep fried, baked
Yeast donuts. Top to bottom: baked, deep fried, air fried
Baking yeast donuts turned them into biscuits!
The cake donuts were more crumbly, dry, and less airy

Sweet Success!

After the donuts are finished cooking, allow them to drip off for roughly 3-4 minutes. Then dip them in the glaze and allow to fully cool. Be sure to try a hot donut fresh out of the frier!

Hands down, the fried yeast donuts were my favorite. However, I found I actually preferred the flavor of the air fried donuts almost equally! They were somewhere in between the yeast and cake donut in terms of texture, but still had the delicious fried taste and crispy crust (without being fried in oil). I, personally, didn’t like the cake donuts very much. They were more crumbly and dry than I would like for a donut.

Advice: Buy Your Donuts !

This was such a fun experiment! Eating donuts right out of the frier/oven was amazing. HOWEVER, would I do it regularly? Ummm no…..


Have you ever tried making donuts? Have I inspired you to give it a go? Let me know below!


Fellows, PJ. 2011. Food processing technology. Principles and practice. 3rd Edition. Woodhead Publishing Ltd. Cambridge.

The Leaning Tower of Donuts

You may also like

1 comment

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: