The Science of Roasting: An Interview with Chris Heiniger

We started our coffee roasting program three years ago. Since then we've been pleased to see the quality of the coffee we roast steadily grow- due largely to the hard...

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We started our coffee roasting program three years ago. Since then we've been pleased to see the quality of the coffee we roast steadily grow- due largely to the hard work of our head roaster Houston Miller. As our volume has increased, however, it's become clear that we need a whole team and not just a single individual roasting our coffee. To help train the rest of our roasting team, we brought in roasting expert and coffee consultant Chris Heiniger.  We sat down with Chris and asked him a few questions about his approach to roasting 

Is roasting coffee an art or a science? 

Good roasting is 100% science.  A mastery of roasting begins with control and repeatability then progresses to experimentation and discovery.  Andy Warhol said “Art is anything you can get away with.”  There are a lot of roasters trying to see what they can get away with because they don’t care to invest the time and effort that the job requires. 

What's your roasting philosophy? 

I want each coffee to taste as good as I can make it, but that goal is influenced by my changing preferences.  Recently, I’ve been trying to roast in opposition to each coffee’s natural characteristics.  For bright, acidic coffees I roast to achieve greater balance.  For naturally balanced coffees, I roast to achieve greater brightness.  This is very different than what I’ve done in the past.

That is more of a roasting strategy than a philosophy.  If I have a coffee philosophy it is: “Don’t ever make someone feel bad about what sort of coffee they like.  No one should ever need to feel self-conscious about their taste preferences.”  

When you're getting to know a new coffee, how do you decide how to roast it? Do you have a default roast profile?

Basically, I try a “slow” “medium” and “fast” profile and then I work out from there.  My “medium” profile is my current favorite.  For that one, I push the temperature up quickly until the coffee begins to change color, then I slow down and stretch out the time as the coffee browns.  Towards the end, I add heat to prevent stalling.  This profile makes for a very lively coffee.  

One thing I know about myself (and the coffee industry as a whole) is that preferences change.  Just because I favor a certain profile now doesn’t mean I believe it to be objectively superior, only that it best achieves my current objective.

How does roasting coffee change depending on the origin, process, or variety? 

Density is a big factor in choosing a basic roast profile. The most general rule would be: Greater density requires greater heat. High-elevation origin, wet-processing, and low-yield varieties usually result in high density.  Low-elevation origin, dry-processing and high-yield varieties usually result in low density.   

What's your favorite part of roasting coffee? 

Trying new coffees. I almost always rather roast something new than something I’ve done before.  In my “normal” life I’m very risk-averse.  Roasting is a chance to live on the wild side.  I’m practically Evel Knievel.

What's the greatest challenge? 

When roasting at home, the greatest challenge is continuing to innovate.  80% of my coffees are only tasted by me.  It is easy to let my roasting skills atrophy.  When I’m roasting at Quills, my challenge is the opposite—I need to be consistent.  If I roast 8 batches of the same coffee, those batches are most likely heading different places or at least being enjoyed by different customers.  In that case, consistency is key.  

What should every coffee drinker know about coffee roasting? 

Roasting isn’t more important than drink preparation, but it is more foundational; the work of the barista (or home brewer) is necessarily built on the back of the work done by the roaster. 


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