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Homeroasters - Home Roasting Coffee Community » THE ART OF ROASTING COFFEE » Roasting Coffee

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Help with troubleshooting my roast profile?
DoubleK	#1 Posted on 08/29/2014 7:05 AM
Newbie Posts: 19 Joined: July 15, 2014	I've been using a stovetop popcorn maker for some time now and have not had much success with quality, so I finally got the equipment to measure bean temp. and log my roast profiles. I found it extremely interesting to see what was happening amidst the beans, and I was definitely able to control the proceedings much more effectively. However, my first batch results are not stellar: noticeably sour, and slightly grassy (especially the first 2 days), though that flavour seems to be decreasing now (3rd day). I was hoping someone could spot my mistakes from the log and roast chart. Any advice is appreciated. Bean/Blend name: Colombia Hulia Acavedo Profile description: Medium roast Weight before: 275g Weight after: 235g Roast notes: 1st crack end is an estimate, I double clicked on the start and botched the reding. Roast seems good. Colour consistent between outside and inside when ground. Had to increase temp more than I wanted to get first crack started as RoR was too low and it was going to extend way past 11mins. Then first crack started to go quickly and I started to compensate by decreasing temp and may have stalled roast (?). Cupping results: - Morning after not impressed. A bit sour and very slightly grassy (water temp for brew?). Smell of beans is good, though (was not good with most previous batches). - 2nd day still not better (same flavour issues), though slightly smoother. Smell still very nice. (17gms coffee, 90degC water, Aeropress inverted for 1 min, 20 sec extract.) - 3rd day still noticeably sour, and slightly grassy, though that flavour seems to be decreasing now. (20gms (ish) coffee, 90degC water, Aeropress inverted for 1 min, 20 sec extract.) DoubleK attached the following image:


Barrie	#2 Posted on 08/29/2014 11:08 AM
Pounder Posts: 504 Joined: April 10, 2012	DK, You are using equipment with which I am not familiar but the aspect that catches my attention is the low weight loss for a roast taken that far past the start of second crack. Unless those beans have an unusually low moisture content, that is not what one would expect? Barrie (San Diego, CA) "So much to learn, so little time." Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).


JackH	#3 Posted on 08/29/2014 12:59 PM
Administrator Posts: 1809 Joined: May 10, 2011	A few things I notice from your graph: I think you need more power at the start of the roast. Your Rate of rise is very low all the way to first crack and it is taking long to get there. If you are already at full power at the start then you may have to reduce the amount you are roasting. I am not sure what type of stovetop popcorn maker you have. It does not look like you are getting the power at the start to really begin heating the beans all the way to the center. ---Jack KKTO Roaster.


Barrie	#4 Posted on 08/29/2014 6:53 PM
Pounder Posts: 504 Joined: April 10, 2012	Jack, Our two comments may be effect and cause? I think he has broken all three of Scott Rao's commandments? :-) Barrie (San Diego, CA) "So much to learn, so little time." Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).


DoubleK	#5 Posted on 08/30/2014 10:03 PM
Newbie Posts: 19 Joined: July 15, 2014	Ok, thanks for the pointers and the Scott Rao reference. I'll try to follow the 3 commandments on the next round. Here are a few photos of my setup and thermocouple placement. Pretty basic, but it should be able to get me reasonable results. DoubleK attached the following images:


JackH	#6 Posted on 08/31/2014 5:40 AM
Administrator Posts: 1809 Joined: May 10, 2011	When running max heat at the start, be sure to reduce it later so you don't fly through the cracks at the end. I usually reduce the heat before first crack, and again in small stages. I learned when first crack will happen by using the same power settings and load size. Usually about 9 minutes into the roast for me. It is something you will have to learn with your setup - how fast it reacts to heat changes. ---Jack KKTO Roaster.


JimH	#7 Posted on 08/31/2014 7:46 AM
1/4 Pounder Posts: 98 Joined: February 17, 2011	Barrie and Jack have both made good points so far. 14.5% weight loss at 20 seconds into second crack is too low, it should have been at least 16%, which means some of the beans were roasted significantly lighter than others. The second clue is the grassy flavor, that only comes from underroasting, which isn't typical of a full city + roast. The picture of the roasted beans gives more clues. Some of the beans have a tight crease and sharp edges, others have a wide crease with rounded edges. Also, it might just be the picture, but some of the beans have darker colored chaff. There also seems to be scorching on the flat sides of some of the beans with wider creases. Putting these all together, I would say that you have a very uneven roast, with beans ranging from city to full city +. I wouldn't put too much weight on the overall color, Colombian beans roast pretty evenly and are well sorted, they almost always have a visually pleasing appearance. You didn't mention your stirring and shaking routine when roasting, both are very important in stovetop roasting. The flat sides of the beans tend to stay face down when stirred, so it is sometimes necessary to also give a shake. Also, you need to stir vigorously, the wire stirrer is too thin to agitate much when it is moving slowly. As to your profile, Jack called it. You need to start with more heat in the beginning, electric stovetops heat too slowly. They also retain heat for longer, so you need to slow down before you reach first crack, if you turn it down too late you will just blow through first crack. The slow response time will encourage you to overcorrect, which is why you went speeding through first crack and then stalled the roast on the way to second. This is the real challenge of stovetop roasting, you need to be planning at least a minute in advance, and you need to know what heat settings will get you where you will want to be. Now that I have made it sound impossible, I am also forced to admit that the best roast I ever did was in a Whirly-Pop. It was the 2008 Ethiopia Bonko "Black Sun," I still dream about how good that coffee was, just like a chocolate covered cherry. I'm not sure I would want to go back to stovetop roasting, but it was definitely a great learning experience.


JackH	#8 Posted on 08/31/2014 12:12 PM
Administrator Posts: 1809 Joined: May 10, 2011	Thanks for the input Jim. "Also, you need to stir vigorously, the wire stirrer is too thin to agitate much when it is moving slowly." The turbo crazy popper also had thin wire arms that did little to mix the beans. Some people were adding small metal blocks clamped to the arms to give them more stirring action. Others would replace the wire arms with new ones bent to increase agitation. I wonder if it would help the stovetop popcorn roasters? I guess a shake every now and then would work too. ---Jack KKTO Roaster.


DoubleK	#9 Posted on 09/06/2014 8:00 PM
Newbie Posts: 19 Joined: July 15, 2014	Thanks for the detailed input, Jim. I'll try to put the advice into practice soon, but I had my brother over last weekend and didn't want to serve him crap coffee so bought some fresh roast that will last me another 4 or five days. I'll be trying the Colombian again soon and keeping in mind all of the pointers. I'm getting my hopes up a bit, but I know I can do this. As to the stirring and shaking, I've only been agitating with the stirring arms, and so I'll make sure to include some vigorous pan shakes every 30 seconds or so. I'll post an update as soon as I have one. Regards, Pierre.


DoubleK	#10 Posted on 09/10/2014 5:04 PM
Newbie Posts: 19 Joined: July 15, 2014	I'll be roasting in a few days and I just wanted to ask one quick question: If I'm starting drop at a stabilized temp of around 210degC (this I've already marked on my stove knob), to what temp would I turn down to slow RoR before I get to 1st crack? It occurred to me that I just need to map my stovetop setting for the lower temp as I'm prepping the pot. I realize that any answer might not be exact for my setup, but a guideline would help. Regards, Pierre.


ginny	#11 Posted on 09/10/2014 7:02 PM
Founder Posts: 3476 Joined: October 24, 2005	Quote I've been using a stovetop popcorn maker for some time now and have not had much success with quality, so I finally got the equipment to measure bean temp. and log my roast profiles I would like to know what results you had BEFORE you decided to use all of the equipment to measure stuff with... ginny


DoubleK	#12 Posted on 09/10/2014 8:32 PM
Newbie Posts: 19 Joined: July 15, 2014	Hard to be precise, as I didn't keep detailed notes and I set the whole effort aside for so long that it's hard to remember. Frequently grassy flavour. Some darker roasts were drinkable or even decent after a couple of days settling (don't think I've ever had a really good "morning after" cup), attempts at medium were usually pretty poor (these are where the grassy and sour flavours were most apparent). The advice to thoroughly shake up the pot for better distribution makes good sense here, as it is likely that I've been getting very uneven roasts. I've worked purely on timings up to now and I've had some that should have yielded acceptable results (first crack at 8-9 mins), though I'm not sure they did. I've also tried preheating in the oven (based on some ideas read elsewhere), but these usually gave pretty poor results too. I just want to get the basics of technique and knowledge down with the equipment I have and understand the reasons for my failures before I consider moving to more automated processes. Maybe I can do well, maybe I can't, but I want to know why I'm not succeeding or at least try to find out. Pierre.


JimH	#13 Posted on 09/11/2014 8:59 PM
1/4 Pounder Posts: 98 Joined: February 17, 2011	It's been about 5 years since my last stovetop roast, so the details are getting a little hazy in my memory, but I'll give it a try. I usually started the roast with the temperature around 180C and slightly rising. For higher grown and dense beans I would go a bit higher, more like 200C. I can't remember what the turning point temperatures were, but times were usually between 60 and 90 seconds. At that point I would start doing small power increases on the burner, trying to maintain the appropriate rate of rise so that I could hit my profile targets. This gets back to what I was saying before, with a slow response time it was all about having a plan for my profile in advance and never allowing myself to get too far off track. I have always believed in the idea of having a declining rate of rise, so I would make a profile plan showing what temperature I should be at for every minute of the profile. Normally I would decrease the power to the burner between 30 and 60 seconds before first crack and the raise it back up to a lower level about 30 seconds after first crack started so I could maintain momentum. BTW, the shaking is less about agitation and more about turning over the beans that have been lying flat side down for too long. A simple flip like a saute pan is usually enough to turn over the beans and get the bottom layer up to the top. Too much time off the heat isn't really desirable. Speaking of heat, using a cheapie perforated aluminum heat diffuser can help even out your roast. If you had a gas stove I'd recommend a cast iron pan, but that causes too much thermal inertia on an electric stove. The flavors you get for the first couple of days after roasting are, IMHO, strongly affected by the baking soda flavors of off-gassing. I usually don't judge too critically until 2 or 3 days after the roast or even longer for Ethiopians and Yemenis. Let me know when my rather long-winded explanations start to bore you.


DoubleK	#14 Posted on 09/15/2014 8:21 PM
Newbie Posts: 19 Joined: July 15, 2014	So here's my new attempt. Bean/Blend name: Colombia Hulia Acavedo Profile description: Dark(ish) roast Weight before: 275g Weight after: 225g (Uncertain, as some beans were lost during a spill) Roast notes: No distinct pause between first and second cracks. RoR curve is pretty erratic. I believe that the larger up spikes were due to my attempts at agitation (picking up the pot and shaking for a few seconds). Missed my chance to turn down heat prior to first crack. I'll let you know how it tastes in a few days. Anyone want to try to call it? DoubleK attached the following image:


DoubleK	#15 Posted on 09/16/2014 1:02 PM
Newbie Posts: 19 Joined: July 15, 2014	Actually, the RoR curve is smoothed out when you close the log and reopen. Here's the graph as it's displayed today. DoubleK attached the following image:


JimH	#16 Posted on 09/19/2014 2:48 PM
1/4 Pounder Posts: 98 Joined: February 17, 2011	I'll be interested to hear how it turned out. The only thing I might have changed in your profile would be to apply more heat early. Your gradual rise up to first crack made reducing the heat unnecessary, but if you were to reach first crack in less time you would definitely need to slow it down before the crack started. (I normally hit first crack between 8 and 9 minutes.) As for shaking, just a quick flip is all that is necessary, the idea is to turn over the beans that have been sliding across the bottom on the flat side for too long.


DoubleK	#17 Posted on 09/20/2014 8:52 PM
Newbie Posts: 19 Joined: July 15, 2014	While it hasn't blown me away, it's been pretty good. It's also gotten quite a bit better than the first few days. I'd love to know what a really good roast of a particular bean was supposed to taste like and then compare to my results, but "pretty good" is certainly nothing to complain about. I don't have any experience with cupping and assessing profiles, so I can't really provide a high level of detail about the flavour. No sourness this time and grassiness doesn't seem to be present. I would estimate the roast to be Full City+ or Vienna; perhaps some of both (if pictures of roast would be helpful or of interest, let me know). Sort of missed the opportunity for a reliable moisture assessment with my spill, but I don't think I lost much and so the estimate is likely reasonable. Anyhow, thanks to all those who provided input. I'll keep working on it and trying to improve! Regards, Pierre.

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