Delicate brown sugar/toffee note. How to amplify?

Discuss roast levels and profiles for espresso, equipment for roasting coffee.

#1: Post by Miltonedgebert »

I'm roasting a hulia Colombian from genuine origin. There's a brown sugar/toffee flavor that I've also found in rum in the background of some roasts.
The odd part is it's only in my light to med-light roasts.
When I did research how to amplify this flavor everything suggested more development time in one way or another. I tried darker roasts and longer development light and medium roasts and that killed the flavor.
The roasts that have had this flavor the strongest were borderline underdeveloped roasts with notable grassiness for a week or two. The flavor fades a bit with the grassiness.
My question: how should I try changing the roast next?
I'm roasting with a stovetop hand crank popper on a gas flame.

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#2: Post by mkane »

The longer you roast it the more sugars you burn away.

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#3: Post by Brewzologist »

For a given green there may be a small range during development where its sweetness is optimal. As Mike said, if you go too dark you burn the sugars away and get more roastiness. And if you go too light you risk getting those grassy and underdeveloped flavors. Roasters may for example do multiple roasts from light to medium where they end each roast say 5F hotter than the last one to find the optimal roast. Or they may extend development time incrementally while holding drop temp constant. The issue for you is this is really hard to do on a roaster like yours right?

Miltonedgebert (original poster)

#4: Post by Miltonedgebert (original poster) »

I wouldn't say really hard, just normal hard. Using time and gas settings gets me pretty consistent. I'll try tweaking gas higher than my most recent batch to see if it improves. I think I almost managed to bake it. I started at med flame, then went all the way low at dry end, and first crack started 5-6 min after that. I dropped at 7 min.

I'm seriously considering a new roaster that has more control and information, but I'm having a hard time justifying it since I enjoy the coffee I roast now.

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#5: Post by mkane »

When we used a Whirly Pop we just turn the flame on high and regulated heat by lifting the pot off the fire. Surprisingly decent coffee but really easy to char.


#6: Post by Milligan »

Sounds like you are at the edge of what your roasting set up can do. You would benefit from consistent temperature data that would allow you to set up a roasting plan for nuanced flavor profiling and reproduce successful results.

The few coffees I've roasted that had the brown sugar note were more in the light to light/medium range. Somewhere around 20-22 roast vision IIRC. Do remember that you can't get flavor that is not there nor in a higher concentration than the bean will innately allow. Something to keep in mind.


#7: Post by GDM528 »

About burning the sugars away:

Sugar doesn't taste as sweet after its caramelized, but not all sugars taste sweet. So, do the sugars in the coffee greens add more or less sweetness after being caramelized?

One trick I've been playing around with that can be emulated on the stovetop:
1) Cook the greens at a steady heat, around 180C/356F, for maybe five minutes or so. The notion is to hold the temperature high enough to caramelize the sugars - but not too high to burn them.
2) Quickly turn up the heat to first-crack+ temperatures and blast'em for no more than a couple minutes - get the color and get out.
The resulting roast can look like a Full City (light oil spots after a couple days) - but not really taste like a dark roast. It confuses the heck out of the few people I've tried it on - they don't know what to think about what they're tasting, but keep asking for more.

Miltonedgebert (original poster)

#8: Post by Miltonedgebert (original poster) »

That's really interesting. Is the temp bean temp, or could I try this by starting the beans on the oven, then moving to the popper?


#9: Post by GDM528 replying to Miltonedgebert »

The phrase "bean temp" can be an existential/philosophical trigger for the HB forums, but you raise a good point. The 180C temperature I mention is from a custom thermocouple stuck in a spinning mass of beans in an air roaster. You might get a significantly different reading from a skillet.

The goal is to hit the threshold temperature that starts the sugars caramelizing - but not so hot as to burn the caramels and/or trigger first crack. Through experimentation I found that 170C was too low (strong grassy notes) and 190 is too close to triggering first-crack. Even with an untrained palate, I found I could detect 5C changes in the caramelizing temperature.

Starting in the oven could work - IF the oven can hold a (very) steady temperature. Mine definitely can't, not even close. Some hacks I've seen online involve using lots of thermal mass (cast iron, cooking steels) to smooth out the fluctuations of the oven's temperature control loop.

Hitting the right temps does seem a bit like threading a needle, but a skilled cook can sear a steak to medium-rare with a nice char on the outside - all without using a temperature probe.

Gotta admit I'll be a little pissed off at myself if it turns out I didn't need to spend a K-buck on a fancy precision coffee roaster ;)

Miltonedgebert (original poster)

#10: Post by Miltonedgebert (original poster) »

Hmm, I have a Dutch oven. I think I'll get that nice and heat soaked in the oven, chuck the beans in for 5-6 min, then finish in the popper. I may be able to try it tomorrow.