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Learning About the Impact of Roast Level
Episode 3 of our Livestream Series

When it comes to differentiating coffees we have a lot of data that we can use. I’ve worked in the industry over eight years and am a sucker for lengthy coffee stories and explanations of how a given coffee was grown and processedI’m hungry for coffee information as a consumer, but for many there’s just one key piece of information that affects their buying decision: roast level. 

Today, a comparison. Light and dark roasts are different in flavor and color, but how? And why? And what about caffeine? Don’t worry, we’re going there. 

Light and dark roasts are different in flavor and color, but how? And why? And what about caffeine? Don’t worry, we’re going there. Join us live at 10:30 am on April 15th to learn more!

1. Roast – time and temperature 

In order to allow coffee to break down efficiently in water we need to roast it. Like any food product the cooking equation is heat + time = flavor. Lighter roasted coffees are dropped from the roaster at a lower temperature and a shorter amount of time than their darker counterparts. Like toasting bread, the more heat and time the more sugars are breaking down and our flavors go from sweetness, to nuttiness, to smokiness quickly.  

2. Brew – rate of break down in water 

With more heat and time in the roaster darker roasted coffees brew faster than light roasted coffeesThey have broken down and become more porous, allowing water to extract flavor more quickly. As a result you may notice faster brew times for darker roasts with pour over brew methods. The coffee is less dense than lighter roasts and the water draws through the porous coffee quickly. 

3. Flavor – terroir and roast 

The initial stages of any roast aim to bring out the natural flavor of a given coffee. Our tongue isn’t great at tasting complex sugars, but it’s excellent at recognizing simple ones. In light roasted coffees we aim to make the inherent sweetness more accessible. Often roasters talk about highlighting the flavors of a coffee’s growing region through lighter roasted coffees, and we find more perceived acidity, sweetness, and complexity. In contrast, dark roasted coffee flavor is representative of the caramelization and carbonization of sugars in the coffee, producing flavors that are more smoky, earthy, and rich. 

4. Caffeine  which roast has more? 

There’s a lot of misinformation about this one. For a long time I was led to believe that dark roasts have more caffeine. More intense flavor means more caffeine, I figured. Then someone told me that lighter roasts have more caffeine“You see,” they said, “the longer it’s roasted the more caffeine leaves the coffee bean.” Great, case closed, I thought. 

I was wrong. Twice. 

In recent years, multiple studies have shown that across all roast levels caffeine is stable and consistent. There simply isn’t enough heat to burn off caffeine, and if there were the coffee would turn to charcoal and likely catch fire. When we find differences in caffeine content it is because of differences in coffee species, variety, and growing environment. The best way to get more caffeine is to drink more delicious coffee. 

5. Age  dark roasts degas faster 

In last week’s blog and livestream we discussed keeping our coffee fresh and the role CO2 degassing and oxidation have on coffee flavor (don’t know what we’re talking about? Click here). Because dark roasts have gone through more chemical breakdown in the roaster they tend to release more CO2, up to 1% of their total weight. Lighter roasted coffees remain denser and don’t release CO2 as quickly. The takeaway, the peak flavor of darker coffees will be a little bit sooner post roast than lighter coffees. 

6. Style  trends and eras 

Before roaster technology and software coffee was roasted in a pan over an open flameIn order to roast the coffee anywhere close to uniform it was taken quite dark, and as roasters evolved dark roasted coffee became tradition. Dark roast was all there was when espresso machines were invented, which is why most “espresso” roasts are typically on the darker side. It wasn’t until about 25 years ago that lighter roasted coffee took hold in the industry. Many companies, like ours, looked to highlight the flavors naturally present in a coffee, and we saw an increased awareness of the coffee supply chain. 

Have a question or a topic you’d like to see covered? Shoot us an email at [email protected], or tune in to the livestream Wednesdays at 10:30am, Brian will be taking questions in the chat! 

Scott Klepper
Scott’s first cafe job served Portland Coffee Roasters. He’s still in coffee eight years later because of the people and community. The free coffee helps.