Posted Wed Dec 20, 2006, 11:11am Subject: Re: iRoast2 - Getting a 12-Minute Roast Out of this Puppy
I had a very dependable profile setup for my iRoast2 but unfortunately after about 6 months my iRoast2 died. I now have a replacement (that's a whole 'nother story–it took Hearthware 3 tries to get it right) and it works extremely differently. I'm hoping that someone can give me a few pointers on how best to change my profile for this new power base.
My old profile:
320/2 min 350/2 min 375/2 min 400/2 min 425/7 min
Before, I would hit first crack at around 7 – 9 minutes on the screen (time left) and then cool manually at around 4 – 6 minutes (just as second crack barely started). I couldn't get a 12 minute roast but I was usually pretty close.
I've now roasted two batches (I've done those beans many times before) with the new power base and it must be running way hotter. My first crack it hitting at about the same time or just a little quicker (just after the motor starts a higher speed when it hits 375 setting) but the second crack starts in less than two minutes after that.
I need to be able to extend the time between the first and second cracks. I think I need to shorten the time at 375 to maybe one minute and then reduce the temperature ??? This just doesn't sound right. Or maybe I should try to extend the ramp-up time by not going to 375 until later ??? Does anyone think the profile TonyR recommended would help me with this situation ?
Posted Thu Dec 21, 2006, 4:55am Subject: Re: iRoast2 - Getting a 12-Minute Roast Out of this Puppy
I did quite a bit of experimenting with the iRoast2, using different beans and profiles. I have graphed all my 46 roasts so far and I measure temperatures with a thermocouple.
Here is the profile I use now: 1- 3 min. 320 F. 2- 2 min. 365 F. 3- 2 min. 390 F. 4- 3 min. 410 F. 5- 5 min. 425 F.
Of course, this roast must be stopped manually. First crack happens at about 7:00 and I usually stop the roast between 11:00 and 12:30.
Looking at the graph below, showing 3 roasts, you will see that the roasts are very predictable. The profile is the red curve. The curves above the profile are the thermocouple temperatures, the ones below are the iR2 temperatures. I still don't understand why the iR2 temperatures are so far off !
I am quite pleased with the regularity in the progression of the roast. The curve is very smooth, except for a slight increase when the fan switches to low speed. House voltage is very stable around 121 V. A/C.
To repeat a roast with this profile is very simple: stop it manually when the color is right or when it reaches the desired TC temperature.
Posted Thu Dec 21, 2006, 6:07am Subject: Re: iRoast2 - Getting a 12-Minute Roast Out of this Puppy
I still don't understand why the iR2 temperatures are so far off !
That's the truth! With the new power base, the iR2 temps that I get when I press TEMP are much lower than my first power base but it actually roasts faster ?!?
To develop the profile I had success with earlier, I tracked temperatures on the iR2 every 30 seconds until I was able to create a slow progression from first to second crack that was repeatable without fail. I was hoping to not have to go through that whole process again but I may be forced to do just that.
I always use 150g and my house voltage is the same as yours.
My main problem now is how to extend the time between the first and second cracks.
The next profile I'm thinking of trying is:
325/4 min 350/5 min 375/6 min
It should use the high speed fan all the time. My concern with it is that it could stall before the first crack and bake instead of roast.
Try it, you'll see... I think that the slow fan speed is required to increase the temperature after a certain point - if not they would not have made the effort to implement it.
By the way, I forgot to mention that I always use 140 g. I feell that 150 g. is ok when the fan is at high speed but is way too much at low speed. The beans have not expanded much yet when the fan switches to low and they rotate quite slowly for a while.
I can understand the variation between the probe and the IR temp but on my IR at the end of each phase the program temp and the IR reported temp are pretty dang close. When it chances phases it takes a bit for the IR reported temp to true up to the program temp but it does after a minute or so and is pretty close for the rest of the phase.
Is there an, iB2? If I hadn't abandoned, fan blasted heating coil, "roasting" years ago (I don't own an iRx, so hit me with a stick) I'd just fly off the handle and say an iB2'd likely do a better job (for me) than an iR2. My (outlandishly dumb) take on blowing fan-air over an incandescent filament to, "roast" coffee mostly results in, "toasting" it more than roasting or even baking it! Kinda, the, "oreo" effect -- black on the outside, white on the inside! The way, "underdone," centers is (to me) what gives the sharp acidic tones to electric fluid-bed roasts, above the natural acidic characteristics of SO's. Some moded, "poppers" and maybe (for all I know) the iRx'es can adjust for slower temperature up-ramp and slower fan speed) and drift their, "roasts" toward, "mellow." My experience (I'm, iron pot prejudiced) gives me the guideline of ~20-25 min. for a roast, finishing off at ~430 deg. (IRT-sensed, from the beans and not a probe sensing the hotter, hot-air near the beans) for a Full City, medium dark, slight oil sheen and an, in-cup, much more mellow than bright taste.
For those who, "love" the bright tastes -- knock yourselves out, with them, 10 minute fluid-bed, "toasts" and I wish you a, Merry Christmas!"
Posted Thu Dec 21, 2006, 7:55am Subject: Re: iRoast2 - Getting a 12-Minute Roast Out of this Puppy
Yirga Said:
Is there an, iB2? If I hadn't abandoned, fan blasted heating coil, "roasting" years ago (I don't own an iRx, so hit me with a stick) I'd just fly off the handle and say an iB2'd likely do a better job (for me) than an iR2. My (outlandishly dumb) take on blowing fan-air over an incandescent filament to, "roast" coffee mostly results in, "toasting" it more than roasting or even baking it! Kinda, the, "oreo" effect -- black on the outside, white on the inside! The way, "underdone," centers is (to me) what gives the sharp acidic tones to electric fluid-bed roasts, above the natural acidic characteristics of SO's. Some moded, "poppers" and maybe (for all I know) the iRx'es can adjust for slower temperature up-ramp and slower fan speed) and drift their, "roasts" toward, "mellow." My experience (I'm, iron pot prejudiced) gives me the guideline of ~20-25 min. for a roast, finishing off at ~430 deg. (IRT-sensed, from the beans and not a probe sensing the hotter, hot-air near the beans) for a Full City, medium dark, slight oil sheen and an, in-cup, much more mellow than bright taste.
For those who, "love" the bright tastes -- knock yourselves out, with them, 10 minute fluid-bed, "toasts" and I wish you a, Merry Christmas!"
Keith, you may be right. Unfortunately, I don't have experience with other methods. However, I can say that with the iR2, the coffee tastes better if the temp ramps up at an easier rate. The profiles that end before 10:00, sometimes as quickly as 7:00, are much too fast in my opinion.
Breaking a roasted bean in pieces does not show the "oreo" effect that you suspect - same colour inside and outside. I think that the iR2 roasts correctly but specialists agree that it favors the bright aspects of coffee.
Your 430 F. guideline for Full City seems to be on the light side. SM's roasting guide suggests 444 F. for FC. With the profile I use now, I get Vienna at about 475 F. on the thermocouple, which is located away from the hot air flow.
Roasting coffee at home is more an art than a science, given the elementary machines we use. However, it makes it quite interesting. Controling the process from the green bean on up makes it quite an enjoyable hobby.
Posted Thu Dec 21, 2006, 10:08am Subject: Re: iRoast2 - Getting a 12-Minute Roast Out of this Puppy
I just tried the following profile:
325 / 4 min 370 / 5 min 390 / 6 min
I got the same results as before. It goes into first crack at around 6 1/2 minutes into the roast (which is sorta okay) and then about a minute and a half later it hits second crack (I should say explodes into second crack). It never even made it to Stage 3 before I had to hit cool.
I'm stumped.
Next up will be:
320 / 5 min 330 / 3 min 375 / 3 min 400 / 4 min
I may need to get that Gene Cafe sooner than I planned!
Yirga Senior Member Joined: 3 Feb 2006 Posts: 659 Location: Big Bend Expertise: Just starting
Posted Thu Dec 21, 2006, 2:49pm Subject: Re: iRoast2 - Getting a 12-Minute Roast Out of this Puppy
Jules_Gobeil Said:
. . .
Breaking a roasted bean in pieces does not show the "oreo" effect that you suspect - same colour inside and outside. I think that the iR2 roasts correctly but specialists agree that it favors the bright aspects of coffee.
Your 430 F. guideline for Full City seems to be on the light side. SM's roasting guide suggests 444 F. for FC. With the profile I use now, I get Vienna at about 475 F. on the thermocouple, which is located away from the hot air flow. . . .
"Oreo" effect is taste, not visual. Most of the physical/chemical effects of roasting, especially fluid-bed, are much more highly concentrated towards the outside (sugar and oil transformations due to degree of roast).
Probe and thermocouple temperature sampling are primarily measurements of the air surrounding the beans. Infra-Red Thermometer (IRT)readings are from the infra-red heat readings from the beans. IRT's don't read air temperatures directly (air is transparent and doesn't reflect infra-red). When heat is being applied to the beans (reflective, convective and radiant) the beans surfaces will of course be hotter than the beans interiors, but with slower ramp-up of heat application, the surface/interior temperature differentials will be closer together, that is why a relatively slow and long heat application will give a more nearly equal heat differential than a rapid heat application, as sensed from an IRT's bean surface readings (~3 deg. F. at the hot end of roasting profiles). A decent IRT in the sensitivity cited is ~$50, a cheap 3 qt. (easily do 1 pound roasts) aluminum heat diffuser SS pot is ~$12, a cheap ~10" SS spoon is ~$5, and a cheap one-eyed hot plate is ~$7 for a Grand Total of ~$74! How much more is an iRx, including a very accurate bean temperature reading (more accurate than a thermocouple sampling mostly the hotter air roasting the beans than the actual beans)? Most of the temperatures cited for various roast profiles were done long ago when IRT's were costing ~$30,000, so super inaccurate probe and thermocouple temperatures were likely used. Those instruments are still around and being used, but why? I'd think mostly because lots of low-end roasters are enclosed and the required direct shot at the beans with an IRT isn't possible, so . . ., drill a hole in the, "toaster" and slip a probe or thermocouple wire into that, MoFo, and read them digital readouts! Never mind there's 30-40 deg. inaccuracy combined, in sensing the air and using a significantly less accurate temperature measuring instrument. Then there's the theory that the temperature accuracy isn't important as long as you keep the same method and use the same temperature reading that got you a desirable roast profile! That'll work up until you change beans and you have to, trial and error, a desirable roast profile with the new beans! And, sure, we're not talking accuracy much greater than ~5 deg. F. But, ~30-40 deg.? Like I've said so many times -- once you start shooting hot air on coffee beans, it alters your DNA and few ever give it up -- they'll spend $millions on mods, profiles, seances, exorcisms, circumcisions, prognosticisms, and electric shock therapy, but don't look for many, if any, to be reborn as a roaster of a different method! I'm one of the few that's done it -- but I could never shake most of the side effects, like, uncontrollably running into tent revivals to be saved from charred coffee and being touched by a faith healer and me falling back to be caught by assistants wearing those mermaid logos on their caps! Char, light? Char, bright?! Sorry, nothing, but, char black and bitter! These are very scary and long nightmares! Asleep, yet?
Posted Thu Dec 21, 2006, 4:37pm Subject: Re: iRoast2 - Getting a 12-Minute Roast Out of this Puppy
Keith,
Well... I'm far from falling asleep. On the contrary, I found it very interesting.
It's quite nice to be able to measure temperature very accurately but, in my mind, it doesn't do anything to improve coffee. Who cares if my thermocouple gives me a 50 F. difference if it is always 50 F. If you look at the 3 curves on my graph, you will see that I can repeat a roast and get the same results time after time. Knowing the exact ending temperature won't change the taste, unless IR has an effect on coffee :-) The same cannot be said for your iron pot manual system with temps certified by infra red. I don't see how you could do 3 roasts and come up with identical results - there are too many variables you don't control - heat source, steer, cooling, ambiant temperature to name a few (all these are under control in a iR2).
Your argument about roasting time is shared by many. It seems that there is a consensus that a longer roasting time is better as long as you don't bake the beans. However, some people prefer fluid bed roasting. Others say that it depends on the beans and on the degree of roast.
Regarding modifications, we share the same opinion. Am I hooked on fluid bed roasting ? Definitively not ! I am a firm believer in "He who has the most toys when he dies wins !" It won't be long before I invest in some other kind of roaster, probably drum. I can also tell you that it probably won't be a popper, an iron pot or some BBQ system. For the time being, I am quite happy with the iR2.
I can also tell you that after 46 roasts, I haven't charred any and all were good enough to drink with pleasure. I am still a newbee - I purchased Silvia and Rocky at the end of July and the IR2 mid September. I've learnt a lot in this short period, enough to be able to make darn good coffee repeatedly. I also know that I still have a lot to learn and I enjoy doing it.
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