Fixing Undeveloped Roasts: Maillard vs Post FC Development

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
User avatar
Joe L
Posts: 9
Joined: 6 years ago

#1: Post by Joe L »

Question:
If your first roast of a new coffee is underdeveloped/has unpleasant acidity, how do you decide whether to:
-Lengthen the Maillard phase
-increase time of roast after First Crack
-Or another solution?

And what are the factors you use in deciding this; Flavors, Origin, Density, Moisture Content, Etc.

Background:
I have been struggling to get a balanced cup out of Costa Rica Tarrazu La Minita. I would either get underdeveloped/unpleasant acidity, or if I roasted longer post 1C I would get a roast that was boring and flat.
Read this thread Roasting Competition by Mill City Roasters - Discussion Thread
Realized I had never fully understood that an underdeveloped roast could be fixed by stretching the Maillard phase, rather than increasing time post 1C. I looked over my roasts and realized that I had never had a Maillard phase that was longer than the "drying" phase.
So I did a roast that was 4:40/5:10/2:10 and was surprised to get a coffee that had really pleasant acidity and good balance. This got me thinking about how you can foresee after your first roast whether the coffee needs a longer Maillard phase?

User avatar
millcityroasters
Posts: 253
Joined: 9 years ago

#2: Post by millcityroasters »

My belief is that "Maillard phase" is a little bit of a misnomer because post crack development is really a brief period of Maillard reaction in the center of the bean.

Chemistry is most reactive at heat so it makes sense (to me anyway) to stretch the post crack time first (15 seconds at a time to gauge effect on development and balance) to firm up a most advantageous development time. From there, I work backwards lengthening and shortening the time between green/yellow transition (end of drying) and first crack.

If I'm really dissecting a coffee, I work my back from drop bracketing various phase times plus and minus time and cupping low, mid, and extended periods against each other right back to the start of the roast. That's usually 6-7 roasts depending on how much coffee I have and whether or not anything much changes.

Soliloquy
Posts: 29
Joined: 9 years ago

#3: Post by Soliloquy »

For filter coffee I would extend post crack development time. Something to keep in mind when extending development time is your drop temp, as this definitely has an effect on the cup. For example, I have a target drop temp of 405-410. If I keep it in this range my coffees taste very clean, above this range they begin to take on roast tones. That said, if I'm going to extend development time, I'll come into first with less energy as to keep the drop temp within this range.

When I was developing an espresso blend for my company (natural Brazil and natural Ethiopia) I had the problem of unpleasant acidity. Extending post crack development time did little to curb acidity, though. The longer I went with development time the more toasty the espresso became, with little effect on acidity. The solution ended up being a very slow roast (14min) with a relatively short development time of 2:20. This roast style improved body and sweetness, while taming acidity and maintaining the fruit and floral notes of the coffee. It tastes kind of bland on filter though.

Kaldi23
Posts: 32
Joined: 6 years ago

#4: Post by Kaldi23 »

It's possible, too, that you may want to adjust your RoR's from start of FC to end. If the roast is flat, consider shortening the duration of FC (more heat). Then, to address the acidity, reduce heat post FC, and extend the roast to the end.

User avatar
Joe L (original poster)
Posts: 9
Joined: 6 years ago

#5: Post by Joe L (original poster) »

Thanks for the replies, I have been processing them all.
Soliliquoy: I had the problem of unpleasant acidity. Extending post crack development time did little to curb acidity, though. The longer I went with development time the more toasty the espresso became, with little effect on acidity
You really succinctly stated my same problem. I too tried a long slow roast that improved the coffee, but was also bland as filter.
Here's my working theory:
Acidity is like a math problem, If you mess up a math problem in the beginning, by the time you reach the end a good result is hopeless. However if you get the first parts correct and mess up the end, the professor still gives you partial credit.
Thus if you mess up the acidity in the drying and ramp phases, you can't save it post 1C. Your only recourse is to roast long enough that all the moisture that the acidity is tied to is dried up.

Sound crazy or sane?

User avatar
drgary
Team HB
Posts: 14345
Joined: 14 years ago

#6: Post by drgary »

millcityroasters wrote:My belief is that "Maillard phase" is a little bit of a misnomer because post crack development is really a brief period of Maillard reaction in the center of the bean.

Chemistry is most reactive at heat so it makes sense (to me anyway) to stretch the post crack time first (15 seconds at a time to gauge effect on development and balance) to firm up a most advantageous development time. From there, I work backwards lengthening and shortening the time between green/yellow transition (end of drying) and first crack.

If I'm really dissecting a coffee, I work my back from drop bracketing various phase times plus and minus time and cupping low, mid, and extended periods against each other right back to the start of the roast. That's usually 6-7 roasts depending on how much coffee I have and whether or not anything much changes.
I like this approach of dialing in the roast back to front, and think it might be focused more quickly by considering Rob Hoos's summary of flavor differences with times spent in each stage. In another thread I summarized his summary of the drying phase.
drgary wrote:A short dry drives in more heat , so it develops higher pressure, can create roast defects (such as scorching), creates lower body and higher clarity. A long drying phase creates lower pressure, the possibility of dull flavor, higher body and complexity. He has a good chart summarizing differences in the roast phases toward the back of the book.
His book is Modulating the Flavor Profile of Coffee, and I found it well worth reading for details beyond what is summarized here.

He summarizes short and long Maillard phase (his term for end of dry to first crack) and Development (first crack onward) as follows:

Maillard: "Lower complexity, lighter body, greater clarity <-> Greater complexity, heavier body, lower clarity"

Development: "Possibly vegetal, greater brightness, lower complexity <-> Possibly flat, rounded acidity, greater complexity"
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

User avatar
luvaffaircoffee
Posts: 24
Joined: 9 years ago

#7: Post by luvaffaircoffee »

Through trial and error I had to overcome this as well as a light roaster. Maybe my experience will help you if it's the same issue.

I've come to find that my air setting was too high. I'd get very clean roasts but with a subtle green flavor or no green flavor but an astringency like all the flavor hits you in one tight mess right away and slightly dry finish. If I'd break open the bean they looked as if they had internal scorching as well but I think even though dark it was underdeveloped.

It's hard to quantify what the proper heat and airflow settings are for a given machine but once I lowered airflow a bit I had better results keeping it light and getting less gradient through the coffee. Much more balanced acidity promoting more sweetness. It's all about how the machine can transfer the heat which is not apparent on the probes. Too much convection was the cause in my case coupled with much too high gas setting as a result to keep ET and RoR in line. I now charge higher use half the gas and less air and it has a dramatic effect on the quality.

User avatar
drgary
Team HB
Posts: 14345
Joined: 14 years ago

#8: Post by drgary »

Rob Hoos did a video Q&A at Mill City Roasters and said that in most roasters 70% of heat transfer to the coffee happens by convection. He recommends doing some test roasts to determine what fan setting gets you to first crack fastest. Then he sets the fan at that level and adjusts the heat source to guide the roast.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

Felice
Posts: 114
Joined: 9 years ago

#9: Post by Felice »

I'd like to suggest examining your drying time. I've found a longer dry, closer to 6 (or even 7 minutes with a natural) and max gas coming close to 280-300f, allows my ramp to be short enough to preserve origin flavor but still be effective. Also, if your drum speed is adjustable, make sure you verify its settings.

User avatar
Almico
Posts: 3612
Joined: 10 years ago

#10: Post by Almico »

Hacienda La Minita Estate is an unusual coffee. Instead of culling out the worse 15% of the beans, they select the best 15% and cull out the rest. It is a very dense coffee and likes a shorter, but hotter post 1C phase. Drive it with lots of heat going into 1C and drop a few seconds past 1Ce, no more that 2:30.

Post Reply