Coffee Roasting     Does high heat application make for a sooner FC?

2021-02-25 22:11

Does high heat application make for a sooner FC?

Good morning everyone.

its quite early on this side of the world.

I'm roasting Ethiopia Shakiso , Natural. High grown at 2300MASL. I have roasted this coffee around 7 times. FC typically on my machine and settings is around 188C-190C for this coffee. Well I was experimenting a new roasting style I read in an article linked below.

http://coffeenavigated.net/high-heat-start/

What Happened was That I planned to reduce my flame around gradually. before I know it I hit FC much faster than expected.

Heat application was close 90% on my 500g (high for this roaster ) , Yellow reduced to 70% and then gradually reducing.

Airflow was from low-med-high as I do in all my roasts.

https://portal.roastpath.com/publicroasts/index/6597102312503260221

Question is, if I have high heat application as it is on this roast, does it affect when I hit FC temperature wise?

Will see how this cup ends up tasting. its more on the light side.

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2021-02-26 09:03

Hi Assim, Ian Picco here with Topeca Coffee. To answer you question, yes, high heat application directly effects how quickly, the robustness, and at what temperature you will hit first crack. To visualize this another way: the higher the heat application, the more internal pressure you are creating in the seed. HIGH HEAT = FASTER ROAST SPEED = INCREASED SEED PRESSURE = EARLIER CRACK TIME =LOWER CRACK TEMP = MORE ROBUST CRACK. The opposite is true for a roast with lower heat input. You will notice with slow roasts, especially when your roast speed is slow coming into first crack, that the crack will be very gentle and sometimes hard to hear.

In my experience between faster and slower roast speeds with a specific coffee, the temperature at which it cracks might have a range of 10 degrees F or roughly 6 degrees C.

Looking at your roast profile, i'd suggest taking things a little slower, and aim closer to a 9 or 10 minute roast, giving a little more development time from yellow to first crack. You are moving really fast entering first crack (28 degrees F per minute). You want to adjust your heat input lower, sometime around when you are turning yellow, slowing to around 20 degrees F during the maillard phase, then maybe slowing down towards 15 degrees F as your approach first crack. I find the 500g roaster retains a lot of thermal momentum, i'm usually dropping the flame completey at first crack or it will run away from me.

My approach with naturals is to keep a relatively short DEV time between first crack and drop, compared to washed coffees. This is because the fruit dried seed has already undergone some chemical degradation before being roasted, as it dried in the fruit and began to get ready for germination; thus converting some of its carbohydrates. With this in mind, it's already a step ahead in converting carbohydrates into sugars, and breaking sugars into acids, which is what is happening at intense rate at the end of roast. So it doesn't need as much time there. I usually stick around 1:10-1:20 for most naturals. I often find if i take it longer I'll loose that fruit and acidity that I'm wanting.

Hope that helps!

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2021-02-27 03:34

Hi Ian,

thank you for the response. highly appreciated.

my typical roast times are generally around the 10min Mark. but I tent to keep development around 1;30. I will try again with lower flame and killing it at FC.

Still trying to find my way. still very interesting how the coffee reacts.

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