The Inner Workings of Krispy Kreme Doughnuts

For over five decades, Krispy Kreme doughnuts have been a beloved treat in the Southern United States, often becoming a cherished weekly tradition for many families. The brand expanded nationwide in the 1990s, bringing its iconic snacks to both coasts amid great excitement. Over the years, Krispy Kreme has also made its mark in pop culture, featuring in numerous TV shows and national publications. Additionally, the company gained significant attention in the financial sector, with its initial public offering (IPO) being one of the top-performing stocks in 2000.

Gratitude

We extend our heartfelt thanks to Rick Norman, Daryl Silver, and the Raleigh Krispy Kreme team for their invaluable assistance with this article (and for the generous supply of doughnuts!).

With growling stomachs and curiosity piqued, we decided to visit our nearby Krispy Kreme to uncover the secrets behind their iconic treats. In this piece, we’ll explore how the Raleigh, N.C., factory store turns basic ingredients into the legendary "original glazed" doughnut. We’ll also delve into the process of injecting chocolate filling into doughnuts and take a closer look at Krispy Kreme’s distribution system.

Mixing and Extruding

The Raleigh store features a massive 750-square-foot sign

The Raleigh Krispy Kreme is one of the brand’s numerous factory stores, which produce doughnuts for both in-store customers and local grocery outlets. All ingredients are prepared at a Krispy Kreme manufacturing plant in Winston Salem, located approximately two hours away. Inside the factory store’s back room, we discovered stacks of doughnut mix, sugar, yeast, fillings, and other pre-packaged ingredients.

The process of creating the original glazed doughnut begins with Krispy Kreme’s proprietary doughnut mix, water, and yeast—the same microorganism used to leaven bread. The yeast is key to the doughnut’s airy texture, as it introduces air pockets, ensuring the treat is light and fluffy, unlike the denser cake doughnut (more on that later).

The Storage Area

Krispy Kreme’s proprietary doughnut mix

The bakers combine the ingredients to create a dough, which is then transferred into a hopper. This hopper supplies an extruder, the machine responsible for shaping the dough into rings that will later become doughnuts. The extruder uses pressurized air to push the dough through a ring-shaped cutter, which consists of a cylindrical cutter nested within another. This design ensures that Krispy Kreme doughnuts are formed as rings, eliminating the need for a separate hole-cutting step.

The Factory Store Concept

The factory store model traces its roots to the very first Krispy Kreme, founded in Winston Salem, N.C., in 1937. Vernon Rudolph, the founder, initially operated a doughnut distribution facility without a retail space. However, customers frequently stopped by, eager to purchase freshly made doughnuts. In response, Rudolph installed a window in the factory wall and began selling doughnuts straight from the production line.

The specialized extruder machine was the only piece of equipment Krispy Kreme did not permit us to photograph. Both the extruder and the unique dough recipe are closely protected trade secrets.

The extruder places the ring-shaped dough directly onto a conveyor belt, which transports the doughnuts to their next destination: the proof box.

The Proof Box

The proof box, also known as a proofer, is a tall glass enclosure containing a conveyor belt that moves doughnut trays in a zig-zag pattern, slowly transporting them up and down through the box.

The proof box’s role is to envelop the doughnuts in warmth and moisture. The combination of humidity and gentle heat activates the yeast without destroying it. As the yeast becomes active, it consumes sugar and releases carbon dioxide gas as a byproduct. This gas expands, forming air pockets throughout the dough (for more details, see How Bread Works).

To ensure the doughnuts reach the perfect temperature, the proof box must maintain precise levels of heat and humidity for a set duration. If conditions become too hot or humid, the machine activates side vents to release excess air. Krispy Kreme keeps the exact proofer settings confidential, as they are a key part of their secret recipe. The dough remains in the proof box for 15 to 20 minutes.

As the conveyor belt moves the dough through the proof box, the yeast causes the dough to expand, transforming it from a thin ring into a fully puffed-up doughnut. Once the doughnut has reached its maximum size, it’s ready for cooking.

Snack Statistics

Krispy Kreme shares the following statistics on its website:

• Daily, Krispy Kreme produces approximately 5 million doughnuts.
• Annually, they create around 2 billion doughnuts.
• Weekly, they produce enough doughnuts to stretch from New York to Los Angeles.
• Each year, they use enough chocolate to fill two Olympic-sized swimming pools.
• Annually, they consume about 1 million pounds of sprinkles.
• Combined, Krispy Kreme stores can stack doughnuts as high as the Empire State Building (1,454 feet or 443 meters) in just two minutes.

Frying

At the end of the proofer cycle, the conveyor belt tilts each doughnut tray, releasing the doughnuts onto a second conveyor belt. This belt carries them through the remaining stages of preparation. The two belts are synchronized via a gear train, ensuring they move in perfect harmony.

The proofer belt releases the dough into the hot cooking oil.

The control panel for the conveyor belt

After exiting the proofer, the doughnuts are fried, a process common to most doughnuts. Frying involves cooking the dough in oil, which quickly heats the exterior, creating the signature crispy texture of Krispy Kreme doughnuts.

A flipper mechanism rotates the doughnuts halfway through their time in the oil.

The conveyor belt transports the doughnuts through a vegetable oil bath, heated to a precise temperature of 355 to 360 degrees Fahrenheit (approximately 180 degrees Celsius). As the doughnuts float in the oil, they are guided by bars attached to the belt. Since they float, only one side is cooked at a time. Midway through, a rotating arm lifts and flips them to ensure even cooking.

The doughnuts are flipped by the rotating arm as they pass through the oil.

Once fully cooked, the conveyor belt moves the doughnuts out of the oil and onto a cooling belt.

Achieving the perfect taste and texture requires frying the doughnuts for an exact duration. Throughout the day, the manager monitors and times the process to ensure consistency. The doughnuts must reach an internal temperature of 85 to 87 degrees Fahrenheit (around 30 degrees Celsius), with each side taking about 45 seconds to cook.

Glazing

The last stage for in-store doughnuts is the glazing process. The glaze, made from sugar, milk, and other ingredients, is prepared in a large mixing container and then transferred to the glazing waterfall reservoir.

A pump moves the glaze from the reservoir to the top of the waterfall, where it cascades over the doughnuts on the conveyor belt. Each doughnut is fully enveloped in glaze as it passes through the waterfall.

When the machine is operational, customers can enjoy the freshest, hottest doughnuts straight from the glazing machine. Meanwhile, doughnuts destined for delivery remain on the conveyor belt, which carries them up a ramp and around the factory room.

Cooling

Cooling Process

The doughnuts take a lengthy, 40-minute journey to cool down sufficiently before being packed into boxes and trays for delivery. This step is crucial, as packaging hot doughnuts would result in a messy and inefficient process.

At the end of the production line, doughnuts move through the chocolate icer, a device similar to the glaze waterfall but designed to coat them in chocolate. Following this, they enter the cooling tunnel, a refrigerated enclosure where the chocolate quickly solidifies. While machine-iced doughnuts are prepared for delivery, those sold in stores are hand-dipped for a personalized touch.

As the doughnuts reach the end of the line, they pass beneath the icer and through the cooling tunnel.

Once they exit the cooling tunnel, the doughnuts are ready for packaging. Workers place them into boxes and trays, which are then stacked onto carts for distribution.

Packaging the Doughnuts

Doughnuts are carefully placed into boxes and arranged on trays.

The packed doughnuts are then loaded onto delivery trucks located at the rear of the store.

When the delivery routes begin, employees wheel the carts onto the trucks. At the Raleigh factory store, drivers cover 14 distinct routes, delivering to approximately 26 merchants per route.

Specialty Doughnuts

While Krispy Kreme is famous for its original glazed doughnuts, it also offers a variety of other types. Most of these are made from the same yeast-raised dough as the original glazed but are prepared in unique ways. Some are coated with chocolate, caramel, or other toppings, while others are filled with cream or fruit. Specialty doughnuts include ring-shaped original glazed versions with different toppings, as well as cake doughnuts like crullers and chocolate varieties.

A Krispy Kreme worker hand-dips doughnuts into chocolate.

Filling, prepared at the Winston Salem facility and packaged in large buckets: Each bucket contains enough cream filling to stuff 1,100 doughnuts.

From a preparation perspective, the most intriguing varieties are the filled doughnuts. These start with the same dough as the original glazed but use a different extruder cutter to create a round shape instead of a ring. The dough goes through the proofing and frying stages and may or may not be glazed, depending on the type. Finally, it reaches the filling station, where bakers inject cream, custard, or fruit fillings into the doughnuts.

At the filling station, bakers load filling material, prepared at the Winston Salem facility, into a pumping machine. The machine features two nozzles and a long button to dispense the filling. To fill a doughnut, bakers place it onto a nozzle, press the button, and pull the doughnut toward them, ensuring it receives the perfect amount of filling.

For cake doughnuts, Krispy Kreme bakers prepare a distinct batter, move the proof box aside, and connect a specialized extruding machine. To create various shapes, such as bumpy crullers, they attach differently shaped cutters to the extruder. The batter is then sent directly to the frying oil, as it doesn’t require proofing.

What’s truly remarkable about Krispy Kreme factory stores is their ability to produce vast quantities of doughnuts with a relatively small team. The Raleigh store can produce 440 dozen doughnuts per hour, while larger stores can double that output. Observing the process reveals the intricate balance of machinery and human effort, all dedicated to crafting the perfect doughnut.