One of the things I feel like I need to grasp more is coffee bean development.


I recently decided to play around with profiles using my SHB El Salvador. I'm using an Ambex YM2, so I turned the damper all the way to the cooling bin, allowing a 50/50 airflow. With a charge temp of 430 and an equilibrium of 160, it is a steady rise to 1st crack at around 9. The roast is a total of 14 minutes.


My dilemma is this, when I crack open the bean, I see the inner and outer part are lighter, while the middle is a little darker. Reason? Maybe I'm approaching 1st crack too fast or going too hard into it? The goal is an even roast through out the bean.



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My typical charge temp is 400. Average time to 1st C is 13 or so. Drop is around 2nd C. 16 to 20 in my Probat 5L.

All Depending what I am roasting, blends/single origins. Several other factors. Roasted beans are very evenly roasted through out. Keep playing till you get your desired color but way more important, your taste profile. Taste and cup / taste and cup / then taste and cup some more. Base it all on your cupping experience with your coffees that you pay through the nose for these days.


Hey Donny. When I roast I typically roast will full air throughout the roast with the exception of nearing EOR. I found that I got better development that way. I think the air slows the development allowing to roast evenly. For a great Central around 3.5lbs, I usually charge to 360 and it bottoms out arouund 190. I hit 1st crack around 10:00-10:30 with a roast time of 14:00-14:30 depending on profile.What is your weight?

I've been very well acquainted with the cupping table lol... 


Joe, do you manipulate airflow at all during your roast? I found that Probat's have lower airflow, at least compared to the Ambex. Where do you equalize?


Paul, I usually charge 4lbs per roast. I think equalizing temp has a lot to do with it as well. When we talk about charge temp, are we talking about the environment temp before dropping the coffee into the chamber or the bean probe?


So if your bean probe equalizes at 190, what does your environment temp do? Paul, I'd like to hear what you have to answer to these questions. So in playing around with different airflow settings, I found that dropping at the stated temp with low airflow, I've been getting better color development, as opposed, to keeping airflow fully open. Not sure exactly why that is, but I suspect that it has something do with with the beans just absorbing all the heat in the roasting chamber.

Airflow is important, but I think you may have too much.  The exposed surfaces are getting more convection heat than the inside, but too much airflow can temper the exchange to the mass.  


The internal sections are getting constant heat from the external surface but without the airflow.  The result is that the rate of development of the outside and the inside are out of sync.  The inside is developing faster.  Reducing the airflow a bit may be all that's required to even out the pace of development.  I wouldn't maintain the same airflow either way.  I'd maintain flame and adjust airflow as needed to achieve a desired profile.  


That having been said, not every roaster desires a perfectly even color throughout the bean.  How do they compare?  

Just a couple of comments. I started roasting on a YM-2 and I would always adjust my airflow. You are right that this little roaster has plenty of air movement but you probably have too much. Try to damper it down and check your results. In addition I was never able to roast more than 3-3.5# in my little Ambex. Depending on the bean, I would get scorching when I got over 3.5#. I eventually settled in on 3.0# batches. I do not think this roaster has enough headroom to accommodate all the bean expansion. Try a 3.0# batch after you have gotten a handle on your airflow.

What do you think about roast duration? I've always aimed at hitting the 300 mark at around 5 minutes and first around 9. Would extending the roast even out the heat and give a more even roast all the way through? I've got to do a little testing next time I jump on.


I will definitely try cutting the charge weight back to 3.5 lbs. to see if i get different/better results/development. I was once screwing around with a 1 lb. sample of a natural Sidamo and the results were remarkable! It was like eating a slice of sweet orange with a mouthfeel that felt like a chevy suburban on the tongue. Not a single note of underdevelopment or bitterness. I was shocked to find out that something like that was possible in such a short roast time. As always when something good happened, I wasn't logging it and don't know what I did.



Try shooting for 1st at something closer to the 12-14min. mark and see if that makes a difference.

Hi Donny,

I used to try and hit 1st crack in 10:30-11:00 with at least 3 minutes preferably 4 minutes till I dropped the batch. I found that anything shorter than 3 minutes would not let the coffee develop its taste. I used to roast everything quickly but the results with the YM-2 seemed to be lacking so I tried stretching it out and it worked for me.

I agree with Timothy. I try to keep my first crack to a minimum of 10:00. Depending on the type of coffee and the profile I try to stretch out to a 3:30-5:00 min. Africans, Good Centrals I try to shorten the 1st to EOR time. Coffees that I want to show off the body and manage its acidity, I extend its stretch.

very generally speaking: I shoot for a balance of time, ET and batch size, considering the bean type. You need temps along the way the beans can handle. Not to high not too low. Avoiding any scorching, tipping, divots. Or over drying from a too slow start. From 300f BT to finish I consider a couple approaches. Most of the time I use a quicker ramp (approx. 5min) to first and a stretched 3-4min finish for brewed and 4-5mins for espresso no matter the finish level. Or you can stretch the ramp to first and shorten the finish for a different effect.

I don't prefer a long ramp long finish or a short ramp short finish

Exact temps and times are going to be roaster specific.

That sounds interesting. Never tried that approach. One of the benefits of having a small roster is that i get to satisify my curiosity by testing without wasting a bunch of coffee.


gonna jump on this week to play around with some variables. am definitely going to play around with charge weights. i think that will change the outcome drastically. while it is a 2k and should be able to handle 4.4 lbs. my guess is that 3.5 is probably more realistic with regard to batch size. Tim, when you were loading 4 lbs of beans, what was your development like? curious if your results were similar to mine. i'll give it a run with an aim for 9.5-10 1st crack and a 14 min EOR.


Farmroast, you bring up an interesting point. what were your findings with regard long ramp/short finish and vise versa?


Initially I was running about 8:30 to 9:00 1st crack with a overall time of 10:30. With these times I could roast larger batches without scorching but I was losing quality in the taste. Perhaps with this roaster you need to run shorter times if you need to run larger batches. Ambex's larger machines roast the same as their smaller one. If you ever upgrade to a larger Ambex, your profiles should remain about the same. Please report back with your results.


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