Up 'til now, virtually all my roasts have been at done in a fairly static ambient environment (78 degrees F. ). Given the timing the cracks and so forth, it's relatively easy to get very consistent roasts and consistent times. Yesterday my air-conditioner gave up it's ghost and I got to apply the timing method to different ambient temperatures - one roast occurred in the morning time when it was fairly cool - around 80 degrees. It took my Alp 14:38 to take the Mexican San Pablo to first crack and I terminated the roast exactly three minutes later at 17:38. I declared the roast a moderate Full City - dark but dry. Well, later on in the afternoon my sister in-law requested some more coffee, so I trudged back to the shop which was now just passing 90 degrees F. I decided that I liked the roast level - it was a little darker than I had originally targeted, but it produced a very fine brew, and I wanted to challenge myself with consistency over a range of ambient temps. My goal was to produce an identical level of roast as the first batch. First crack occurred at 13:59, and I timed three minutes to cooldown, ending the roast at 16:59. 10 degrees ambient temperature difference made a 39 second difference in the roast time. However, when the two batches are put side-by-side, I could see no difference in the level of roast. I consider that a successful experiment. For the San Pablo, which is a smaller bean, I discounted the first erratic pops (one starting as soon as 12:and some change) because a very few of the beans actually fall out through the holes in the drum into the chaff tray or get stuck in the drum holes and roast at an accelerated pace due to closer proximity to the burners and the fact that they were no longer being agitated. It's fairly easy to recognize the first crack though - the first crack usually announces itself with a small group of pops and then a constant poppity-pop over a period of time. On large bean coffees like the Kona or Zimbabwe, it's a little easier - the first pop or two generally heralds the onset of first crack. I'm tickled. I still can't wait for the air-conditioner repairman, but it's neat applying some general timing rules to achieve a consistent roast in spite of the differences in ambient temperature. I wish I had the lap timer when I was using the West Bend Poppery II or the HWP. If you're putting together a must-have list for Christmas (or sooner) make sure a digital lap timer is on it - preferably one that can display two times simultaneously. Heck, they're cheap enough nowadays. I'm surprised Tom hasn't put one on his page (hint, hint :). Cheers, Mike |
Mike: Very interesting, though it's a bit depressing to have to add room temp to the daunting list of variables. Now I'm wondering if I need to build a little insulated chamber for the Alp to sit in while running... (just kidding, just kidding!). Kathleen |
Hee hee - similar has been suggested for those poor souls who has to roast outside or in the garage in the middle of winter. Ambient temp certainly does make a difference, but within a 20 degree range - 70 to 90 it's not too catastrophic and by timing the roast from the first crack consistent roasts can be had. Cooler than 70 - adding a little to the normal post-1st-crack time would be recommended depending on how much cooler it got, and warmer than 90 or so you would probably want to take a little off the post-1st-crack time. For instance - my favorite coffee roasts to perfection at 3 minutes past first crack. For a comfortable range of temperature that works okay. If it gets too cool, the roast is slowed significantly to where 3 minutes would produce a lighter than targeted roast so adding some time to compensate for the longer roast would be the thing to do. Vice-versa for hotter ambient temperatures. This is what outside roasters have to contend with, but it does make you accutely aware of what's going on - it's easy to get complacent when roasting time after time in a fairly static ambient temperature with a narrow range of coffees. It's interesting applying all this theory into practice. Kathleen Tinkel wrote: <Snip> |
Ambient temperature: I roast in my garage. Now that it's getting cool here in Maine (temperature dropping below 10C at night), I've been worried about my roasting. I've "built" a little hut for my HWP out of a milk crate and some boards. "Built" is too grandiose, it's just that the boards lie so that most of the HWP output is contained in a one cubic meter enclosure. I pre-heat the HWP by running it for a minute or two before putting the beans in. So far it works, but we'll see what happens when it hits -20C. KN |
I'm considering a similar idea using an extra kitchen cabinet that I have sitting around. My thought is too provide a positive exhaust fan to pull all of the roasting exhaust through a vent to the outside. The negative is that it will make it more difficult to hear the cracks. At this point, I've got enough data on my HWP to simply set the dial and let it run on it's own for most of the coffees I roast on a regular basis. Maybe I need to install a microphone inside the box, and run it through an equalizer set to pick up the cracking sounds? I know that I don't want to try roasting outdoors this winter, nor do I want to hear the grief from my family when I roast in the kitchen with the vent hood. Todd <Snip> |
<Snip>
This is what I did before I had a store to stink up with smoke. (well ...
its not a stink since I love the smell). But those cool temperatures are
coming and I am sure there will be a lot of new brainpower added to the
age-old roasters problme of ambient air temperature....
T
"Great coffee comes from tiny roasters"
Sweet Maria's Home Coffee Roasting - Tom & Maria
http://www.sweetmarias.com |
---- Begin Original Message ---- From: Tom & Maria Sent: Mon, 18 Sep 2000 23:24:38 -0400 To: homeroast Subject: Re: + Consistency <Snip> (temperature <Snip> I've .........major snip........ <Snip> ---- End Original Message ---- Ouch. Guess I shouldn't worry about my kitchen ambient running from 78 F summer to 68F winter too much, huh? I think the newer HWPs run a little cooler than the older ones, according to my experience and posts I have been seeing. It takes 9:30+ to start seeing any oil on the beans.....although a roast at 9 min. will develop a little oil after a couple days. All in all, I'm quite happy with this little jewel, it would be nice if it was a little bigger, but......My local Costco has installed a roaster in the store; fully vented so no trace of odor. They sell a roasted lb. for ~$6.50, Sumatra, Costa Rican, Columbian, etc. But I wanted to try a sample, what they give you is slightly brown hot water. Yuk, is that how people really like their coffee? Mike |
Todd, I posted some pics awhile back of a roasting cabinet that I made from a utility wall cabinet for the HWP. My goal was to achieve greater temperature consistency and to control the smoke/odor. It seems to do both pretty well. You can find the pics at:http://homepage.interaccess.com/~pierces/There are also some second-by-second temp profiles for my HWP and a comparison of roasting times for different ambient temperatures. I recently modified the cabinet to handle the Alpenrost (not kidding at all Kathleen!)and have posted a picture of the new mods on the same site . There is also a temp profile for a couple of consecutive roasts in the alp which might be of interest to all. ..........................Kent At 10:33 PM 9/18/00 -0400, Todd wrote: <Snip> |
You've done exactly what I was envisioning. Thanks for posting the message with the URL Since you have the temperature profiles, I'm assuming that's what you roast by as opposed to sound. Can you hear the cracks when either unit is running inside of the cabinet? Thanks again! Todd <Snip> |
Todd, Like a lot of guys my age I have 'nam ears -- a big high freq deficit from being way too close to a variety of things that went BOOM! -- but I don't have any trouble hearing first or second crack. I did have to learn to distinguish between beans hitting the side of the glass and early stages of 2nd crack in the HWP. I roast by any piece of info that I can get -- sight, sound, temp -- and unless you fine tune the air pressure to a gnat's eyelash, there will still be enough smell for you to tell when the shift into 2nd crack occurs, as well. ..........................Kent At 09:04 AM 9/19/00 -0400, Todd wrote: <Snip> |
Kent: Wonderful pictures - very interesting. I'm roasting indoors so don't have the ambient temp problems you and some others worry about. On the other hand, it would be nice to contain the mess a bit - I roast on top of my stove to take advantage of the hood; no matter what I do, chaff gets in the burners. And I can't cook and roast at the same time. Thanks also for the data on the back-to-back Alps roasts. Did the beans also taste about the same from both roasts? Kathleen ------ |
In a message dated 9/18/00 9:29:02 AM, KTINKEL writes: << Very interesting, though it's a bit depressing to have to add room temp to the daunting list of variables. Now I'm wondering if I need to build a little insulated chamber for the Alp to sit in while running... (just kidding, just kidding!). >> Just read this one - apparently these variables are aberrant. -Todd L. ALP (the one and only) |
In a message dated 9/18/00 10:27:01 PM, tom writes: << This is what I did before I had a store to stink up with smoke. (well ... its not a stink since I love the smell). But those cool temperatures are coming and I am sure there will be a lot of new brainpower added to the age-old roasters problme of ambient air temperature.... >> Time to start brewing Beer! 8-) -Todd L. |
Kathleen, I don't have notes about the taste of those particular roasts, but it has been my experience that sequential roasts in the alp have the same flavor if taken to the same stage in the roast (in this case 2nd crack and the same temperature). Even though the 2nd roast took a minute less than the first roast, the slope of the time/temp curve is virtually identical for the two roasts. By comparison, the time/temp slope for the HWP is initially much steeper and the taste of a roast taken to 2nd crack is much different. ......................Kent At 11:24 AM 9/19/00 -0400, Kathleen wrote: <Snip> |