How Doughnuts are Made

The humble doughnut holds a special place in the global collective consciousness, consistently ranking as one of the world’s most popular treats. But have you ever wondered, just how are doughnuts produced? We’re way ahead of you. Read on to discover how doughnuts are made.

Engineering How It’s Made
24 August 2022

Whether iced or filled, sprinkled or glazed, the simple sweet treat of dough fried in oil is beloved around the world. What’s more, it’s big business, with annual global sales consistently in the tens of billions of US dollars.

So, how are doughnuts produced on such a large scale? How do you make doughnuts at home? And how are donuts made in a factory? What’s more, how are glazed donuts made? Let’s jump right into the frying pan and find out.

How Doughnuts are Made: A History

Before exploring how doughnuts are made today, there’s one important question. Who invented the doughnut?

American ship captain Hanson Gregory claimed to have done so in 1847, much to the annoyance of the Netherlands, who claim it derived from the olykoeks (oily cakes) brought to New York by Dutch migrants. Then there’s the recipe book of one Baroness Elizabeth Dimsdale dating back to 1800, which contains instructions for making a suspiciously doughnut-like confection.

The Berbers of the Maghreb might also claim the doughy crown with their sfenj, which dates back at least as far as the 13th century. Even this however is dwarfed in the mists of time by archaeological discoveries of what may have been the first ever doughnuts. Like the Bronze-Age ring shaped loaves found in an Austrian hillfort dated to 1000 BC. Or the rings of dough on staffs in the tombs of Egyptian pharaohs. Even the Bible gets in on the act, with many references to fried breads.

So while it should come as no surprise that countries and cultures around the world would clamber to be credited with the invention of this delectable doughy delight, the truth is nobody’s quite sure where or when the doughnut was invented.

What is known however, is that it was a Russian immigrant to New York by the name of Adolph Levitt who invented the first doughnut machine in 1920. From there doughnuts quickly became a runaway hit and were widespread by the 1930s. Krispy Kreme was established in the 1950s using a machine known as the Ring King.

Flash forward to today and Krispy Kreme makes approximately 1.1 billion of the 10 billion doughnuts produced annually in the US. So, how do you make doughnuts on such a large scale? We’ll look at this shortly. First, let’s start small. How do you make doughnuts at home?

How Doughnuts are Made at Home

Doughnut making in progress (Photo: mikroman6 via Getty Images)

So, how are doughnuts produced? The internet is full of recipes explaining how doughnuts are made. Ingredients commonly include:

  • caster sugar;
  • strong white bread flour;
  • eggs;
  • fresh yeast;
  • water;
  • unsalted butter; and
  • plenty of oil (usually sunflower oil) for frying

To make the dough, all of these ingredients, except the oil and butter are mixed, then the butter is added in slow increments. Next comes proofing, which is the process of allowing the dough to rise.

For this, it is left covered, usually at least until it has expanded to double its original size. The dough is kneaded, rolled and formed into rings, before being deep fried until golden brown, which takes a mere 30 seconds or so on each side.

So, that’s how homemade doughnuts are made. But what about mass produced ones? How are donuts made in a factory or in bakeries?

How are Doughnuts Produced Commercially? 

How doughnuts are made on a large scale differs from the homemade kind in several ways, not least in the ingredients used. Commercial doughnuts have far more ingredients than those made at home, usually beginning with a ready mix of some sort.

There are two main doughnut making methods, differentiated by the raising process:

  • Yeast-raised doughnuts: These light, airy rings are the most commonplace type and count glazed doughnuts as members. This method leavens the dough (makes it rise) by fermenting yeast, thus releasing carbon dioxide and giving them a honeycomb structure.
  • Chemically raised doughnuts: Baking powder is the leavening agent here, creating a denser, cakier doughnut with more versatile flavouring options. Chemically raised donuts are much quicker and easier to make than their yeasty counterparts.

We’ll also explore the baking soda method later. For now, we’ll focus on how are doughnuts produced in factories, which usually means yeast-raised ones. The mix for these commonly incorporates:

  • Flour (wheat and/or soy)
  • Shortening
  • Sugar
  • Milk solids, usually as whey powder
  • Yeast dough conditioners
  • Gum
  • Artificial flavours
  • Raising agents
  • Egg powder
  • Ground nutmeg
  • Salt

The bakery or factory then adds fresh ingredients such as milk, water, yeast and eggs in the factory stage of how doughnuts are made, before proofing and frying, as well as adding any fillings or toppings.

How are Donuts Made in a Factory?

The production line at Krispy Kreme Doughnuts (Photo: Jeff Greenberg via Getty Images)

Doughnut factories such as those of Krispy Kreme and Dunkin Donuts are highly automated, sanitary environments designed to create thousands of donuts each day in a standardised format. Ingredients are carefully measured, quality is carefully controlled and donuts are transported through almost the entire process on a series of conveyor belts. Oh, and everything is done on a massive scale. For example, the doughnut mix comes prepackaged in large bags weighing in excess of 20kg.

Measuring and weighing of ingredients is meticulously controlled both by digital scales and staff oversight, with the mixing and kneading performed in industrial sized mixers on automatic timers. As an example, a batch is kneaded for approximately 15 minutes.

Forming & Shaping

Describing the formation of ring doughnuts includes one surprisingly controversial revelation: The hole in the centre is built in, not cut out. There is no land of delicious extracted donut centres.

Instead, pressurised air forces a continuous flow of dough through an o-shaped tunnel, with a cutter at the end, perfectly configured to slice the hollow length of dough to a uniform thickness, usually of around half an inch.

This neat device, known as an extruder, spits out one fully formed ring of dough after another onto trays of a dozen each. The average factory extruder might form some 1440 doughnuts an hour.

From there, the conveyor belt transports the trays to the proofer.

The Proofing Box

The hot and humid conditions in this glass box are constantly monitored to provide the perfect environment to activate the yeast, usually at around 51 degrees celsius. The dough travels up and down inside the proofer atop the conveyor belt, meandering continuously for around 15 to 30 minutes. In this time, the yeast feeds on sugar and releases the carbon dioxide gas that puffs it up.


Now roughly doubled in size, the dough continues on its conveyer belt journey. The next stop is a bath of oil – usually vegetable-based – heated to around 180 degrees celsius. The doughnuts fry as they float along, moving on rotating cylinders which feed them into an automatic flipper. Again this is all precisely timed, with each doughnut side cooked for around 45 seconds.

How Are Glazed Donuts Made?

At this stage of the factory process, the donuts are once again conveyed, but now their paths diverge depending on their intended finish. Some will pass under a waterfall of icing, completely coating their top and sides. Then, of course, there is the iconic glazed version. How are glazed doughnuts made? Well, they have their own waterfall, where they are showered with glazing. In terms of describing “how are glazed donuts made” from the perspective of ingredients, the glaze is most often a combination of sugar, milk and syrup or vanilla.


It takes around 40 minutes passing through a refrigerated cooling tunnel for the newly glazed or iced doughnuts to cool. Again, these might then be ready for packaging, or they might have one more stop, the finishing station, where any sprinkles or other toppings are applied.

How are Filled Donuts Made in a Factory?

Filling a doughnut precisely (Photo: Jure Gasparic / EyeEm via Getty Images)

So far, we’ve only talked about ring doughnuts. There are, of course, also the perfectly round filled variety.

These will have been shaped by a different extruder, without a hollow centre. And they go to the filling station.

There, a specialist machine injects two or more doughnuts at a time with the precise amount of filling, creating a veritable wonder of taste combinations.

How are Doughnuts Produced via Chemically-Raising?

A delicious stack of doughnuts (Photo: David Freund via Getty Images)

The main difference between yeast- and chemically raised doughnuts is that the latter do not require proofing. They leapfrog straight from the mixer to the frying bath.

Explaining How Doughnuts are Made

Naughty by so nice! The thrill of eating a doughnut! (Photo: Elizabeth Fernandez via Getty Images)

We’ve gone full circle in this sizzling account of how doughnuts are made. From fossilised pastries of the past we went on to explore how are doughnuts produced at home versus how are donuts made in a factory. We even looked at icings, fillings and how are glazed donuts made. It’s enough to make you work up an appetite.

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