No matter how you enjoy your coffee, though, it likely has one quality in common with nearly every other coffee: it is roasted in a drum or barrel.

But on the fringes of coffee-enthusiast society, you may find talk of air roasting coffee beans. It’s the method that could have been (but never actually went) mainstream. Despite the fact that air roasting methods have been around since the 1970s, only a small percentage of coffee served around the world today is air roasted.

What is Air Roasted Coffee?

Air roasted coffee is coffee that is roasted on a fluid bed of hot air as opposed to the traditional method of tumbling in a hot steel drum.

These producers air roast their coffee beans because the method is faster, cleaner and easier to duplicate batch after batch. Coffee drinkers who prefer air roasted coffee insist the taste is smoother and less bitter than traditional drum roasted coffee.

Chemical engineer and coffee industry consultant Mike Sivetz is most well-known as the inventor of the fluidized bed roaster and advocate for specialty coffee. He sought his patent for the first fluidized bed roaster in 1976.

Disappointed with traditional roasting processes, Sivetz decided he could come up with something better, beginning his designs with a gas-fired device built in his garage. “Sivetz roasting,” as air roasting is sometimes called, became mildly popular in the 1970s. But despite the benefits it offers, it still remains a relatively unheard-of process today.

The Air Roasting Process

First of all, to understand why some people prefer air roasted coffee, it is important to understand how air roasting works. Generally, coffee bean air roasters using a fluidized bed will follow this process:

Place the beans into the roasting chamber where they will levitate on a bed of very hot air pushing through the chamber in one continuous motion. This apparatus is called a “fluid bed.” As each individual bean floats in this vortex, it is roasted on all sides at a consistent temperature maintained by the air throughout the process.

As the beans are roasted, they will pop and crack until the chaff (outer husk of the bean) is blown off and into a collector chamber before it settles. This chaff is continually removed and separated throughout the process.

When the desired roast level (determined by preselected roasting time and temperature) is achieved, the cooling process begins.

What’s The Difference Between Air Roasting and Drum Roasting?

Now that we’ve established a firm understanding of the air roasting process, let’s analyze the difference between air roasting and drum roasting coffee beans.

Fluidized Bed vs. Mechanical Arm

Instead of relying on a fluidized bed of hot air to roast the coffee beans, drum roasting relies on a mechanical arm to stir the beans inside a steel drum. As the beans tumble against the scalding hot metal interior, the temperature of the beans changes with each new position.

Taste

When consuming air-roasted coffee, the very first difference you may notice is the taste. Coffee drinkers who prefer air-roasted coffee claim it is the purest taste, less acidic and less bitter than drum roasted coffee. The reason for the difference in taste comes down to the chaff, that outer skin that comes off the bean during air roasting.

Chaff

In traditional roasting, there is no mechanism or means for removing the chaff during roasting. So rather than separate it, this debris remains in the drum or barrel. Sometimes it burns and often it smokes, but this burning and smoking ultimately affects the flavor of the coffee, particularly dark roasted coffee.

Roasting Time

For coffee roasters, a primary difference is roasting time. Air roasted coffee has the shortest roasting time, which can be as little as 4-8 minutes, while drum roasted coffee can take upward of 15 minutes to complete.

Halving the roasting times means more batches, better productivity, and ultimately more income for the roaster. Longer roasting times can also mean more flavor loss. The longer the coffee roasts, the further it gets away from its true flavor.

Drum roasted coffee is roasted “to color,” meaning that traditional coffee roasters rely on the coffee within the drum to look a certain color to signify that it is done. However, this method is somewhat inconsistent because color can be a subjective measurement, and small variations in taste can occur as a result of different roasters stopping after different roasting times.

While the difference between brown and darker brown might seem negligible, it can mean the difference between a City Roast and a French Roast. If you find a coffee you love, those small changes can mean a drastically different taste.

You want the same taste again and again. As Mike Sivetz once put it, “When it comes to coffee, the last thing to trust is your luck.”

Air roasters, on the other hand, roast their coffee “to temperature,” stopping the roasting process once it reaches a predetermined time and temperature. By roasting “to temperature,” air roasters are able to be more precise, duplicating batches to keep the same color, flavor profile, and aroma coffee drinkers love.

How to Choose a Coffee Roaster

In 2002 — more than 20 years after Sivetz fluid bed roasters began to be used — disappointed in coffee drinkers’ stubborn unwillingness to change, Mike Sivetz wrote, “Traditional tastes tend to persist in the food industry over time. One can only expect a newer method and product to take some years to replace a traditional one.”

Whether you choose to continue drinking drum roasted coffee or venture into the world of air roasted coffee, it remains equally important to choose a quality coffee roaster. Lea Ceasrine, co-founder of sustainable coffee subscription Bay Roasters, advised coffee consumers to look for these two aspects:

1. Roast Rate

This information will be stamped on the package. Ideally, you do not want to buy anything roasted over two weeks ago. It’s true that coffee beans don’t really have a shelf life, but anything roasted over a month ago is not fresh.

2. Source

Small, local, family-owned roasters have the best direct supply chain. You know where you’re getting your coffee from and can trust that they are paying their coffee farmers fair wages. Supporting local is a great rule of thumb.

While there is a lot of debate around organic vs. non-organic coffee, the label generally doesn’t mean much, according to Ceasrine. Small, local roasters often source from small farms in Central America or other areas where farmers cannot afford certifications.

Be sure you buy coffee from a roaster you can trust to use quality, fair trade coffee in a roasting method that gives you the taste you enjoy. As Mike Sivetz wrote, “Every man has the right to know what’s in the coffee he’s drinking.”