first coffee roast in modified Popcorn Pumper

I cleaned off my work bench the other day, organizing and storing the bazillion fasteners, tools, scraps, instruction manuals, and spare household pets. It was a beautiful blank slate for the first time since we moved in, what, five years ago? And it was literally crying out for projects!

While cleaning up the rest of the garage I found the Popcorn Pumper, which I haven't used for roasting coffee since finding the Poppery II. Seemed like a good time to toy with a few modifications. I started small, simply bypassing the thermal switch (and thereby creating a magnificent fire hazard). This is just a matter of soldering a wire between the terminals on either end of the thermostat and fuse, more or less according to this Engadget how-to. This keeps the heating coil on constantly, delivering significantly greater heat. (This great article has more explanation of the circuitry in these things.)

I also made an aluminum chimney to replace the bulky plastic hood, which really does not care for these temperatures. This was just some leftover aluminum roof flashing, rolled and fastened with J-B Weld.

The first trial run was excellent! I took it outside, preheated for a minute, and added enough beans for there to be some agitation but no swirling. I stirred occasionally with a wooden spoon, which is now possible since I can get straight into the chamber. The difference in heat was obvious. Roasting time was greatly reduced, and it's clear that any desired roast can be achieved without baking the beans. The chaff was all blasted directly out the chimney.

I didn't take any measurements but the results are clear. This is an enormous improvement over the original machine and the Poppery II as well. This was Sweet Maria's Classic Italian espresso blend and I took it to a very dark roast with a speed and consistency I've never seen.

2010-09-13 update: Tried again, this time shooting for a lighter roast. 4.65 ounces for five minutes produced this:

It was just entering second crack. That may be a little faster than is desirable. The roaster could have handled more beans. Adding beans generally speeds things up but I'm not sure that would be true in this case where I'm doing some manual agitation until the beans are light enough to fluidize. I guess the best approach will be to vary the supply voltage.

stovetop versus hot air roasting test 1

I'm finally getting around to doing some controlled tests between hot air coffee roasting and stovetop popper roasting. For this test I used Sweet Maria's Moka Kadir blend.

Stovetop roasting was outdoors at about 50 degrees, high humidity, no wind. Hot air using the Poppery II was indoors at about 68 degrees. Beans started at room temperature in both cases.

I roasted 10 ounces in the stovtop roaster, ending up with 8.43 ounces. Temperature was 550+ at bean drop. I ran it hotter than usual, staying above 350 for the duration and climbing to around 450 at the end. It came out at 4:20 with heavy smoke and some beans well into second crack. This was a fast and uneven roast.

I roasted 5 ounces in the hot air popper, ending up with 4.2 ounces. I preheated the popper for a few minutes and agitated the beans for the first few minutes as well. By three minute it was fluidizing unassisted, with a few already very dark and others barely colored. It came out at 8:00 with moderate smoke, when I judged the color to be comparable. It was even, as usual for hot air.

The closeness of the final (proportionate) weights may be a good indicator of the average darkness being nearly identical.

Toss-cooled both outdoors. There's a nonlinear relationship between mass and cooling time; the smaller batch takes perhaps one fourth as long. I don't have a way to measure the internal bean temperature so don't know whether that's also a factor.

Stovetop results:

Hot air results:

Tasted after resting for a day, pulling single shots. The grind was a little fine (30+ seconds). The hot air beans were a touch slower.

The stovetop-roasted coffee's initial moderate acidity mellows into sweetness, some fruit. Can detect both the very dark and bright tones, probably due to variability in bean doneness. It has both a slightly underdone and a slightly overdone quality, but it's quite good. I think it will be better in a day but it's totally drinkable.

The air-roasted coffee produced much more crema and the espresso had a much stronger coffee aroma. The acidity stays on the tongue considerably longer, with the sweetness blending into it. There is less complexity in the flavors and it's just not as lively. More body. Also good, but I think I slightly prefer the stovetop variant.

For the next test I should slow down the stovetop roast and try to reduce the variability in darkness. This can be done by starting at a lower initial temperature, running at a lower gas setting, or using more beans. Weather is a factor, too. While my opinion is that some variation is actually desirable, being responsible for the more interesting flavors, a better comparison can be made if it is limited.

Overall, a pretty successful test. I'll happily drink both of these roasts straight, with milk, and as Americano.

auriferous espresso in the Poppery II

I tried five ounces of Sweet Maria's Auriferous Espresso blend in the Poppery II. This was an amount that I thought would work well, based on the first attempt at four and the second attempt at six ounces.

I let the popper preheat for a few minutes, and gave it a shake now and then during the early going since it was not fluidizing. The beans in this blend are generally larger than the beans in Moka Kadir; perhaps that's a factor. At ten minutes I pulled the plug, with it very audibly in second crack. Color is even. Final weight was 4.13 ounces.

There was enough smoke to set off the alarm, even though I was running the fan on the range hood. That did not happen last time; I was surprised.

After a couple of days rest, I'm pretty pleased. It's a touch dark but I don't detect any other flaws. I think I'm ready (on a day with slightly less revolting weather) to do some head-to-head comparisons between the Poppery II and the stovetop popper.

second use of Poppery II

The Poppery II does work better with more beans. The first attempt was with four ounces of Moka Kadir; the second was with six. In eight and a half minutes it produced a glossy dark roast with plenty of smoke and cracking. Final weight was 4.87 ounces, or 86% of original weight. That's an interesting result. I usually see something closer to 80%.

The main problem is that while the beans are heaviest they aren't getting much agitation. It takes a few minutes before any degree of fluidization is evident. Some of the beans at the bottom were done very quickly. Giving it a shake now and then seems to help.

Tipping it back doesn't appear to be a good idea. It seems to interfere with the fluidization. A few beans do pop out when it's level, but not as many as I'd feared.

This roast ended up slightly uneven, but I think it will be better next time. Things to try:

• no tilting
• occasional manual agitation
• five ounces

The immediately-pulled shots were an improvement. Lots of crema, though not the foaming torrent from the last roast. The under-roasted flavor is gone and the solvent notes are faint. It's still pretty bad, as experience suggests will be the case before resting for a couple of days, but I think it may turn out all right.

After resting for a day there was some improvement. It's darker than I usually take Moka Kadir, with a bit of char. Aroma is nice, with chocolate dominant.

Update: It's not improving. It's not producing good espresso at all, in fact. I wonder whether I just need to clean the espresso machine.

Update: Indeed. That thing was disgusting. It's now decalcified and every user-accessible component is spotless. Whisked out the grinder, too. Pulled shots pretty close to the ideal time/volume. The result is a much cleaner-tasting cup. My main objection is probably the darkness of the roast, which I think has destroyed some of the fruitiness that I've tasted in Moka Kadir in previous roasts.

first attempt at roasting with a Poppery II

I discovered another hot air popcorn popper at the thrift store and felt it worthy of the $3 investment. It's a Poppery II and is compact and quiet compared to the Popcorn Pumper.

I immediately roasted four ounces of Moka Kadir. Interestingly, my results were almost identical to the first time I roasted in the Popcorn Pumper. After 15 minutes I shut it down, having produced almost no smoke, no sustained cracking, and at a much lighter roast than I would normally use.

The result for the first shots I pulled were about as originally described. Under-roasted, solvent aftertaste, very little fruit or sweetness, and low aroma. After a day of rest the only change was that the sweetness may have developed a bit and the aroma was improved.

An interesting effect was that the espresso was produced very quickly and with an absolute torrent of foaming crema. This behavior lessened slightly on the second day. I didn't experiment to see how far I'd have to reduce the grind in order to mitigate it, since four ounces (3.2 after roasting) is not much to play with. There may be some underextraction that would account for a bit of the flavor, but I don't think that's the main factor.

I will try again with six ounces to see whether I can get results more like these. However, that quantity is going to be pretty close to jumping out of the top of the roasting chamber. I may need to tip it back slightly. This is a nicer piece of equipment to use, but at this point I don't know whether it can get the job done.

Update: After a few days, no real change. It is not going to improve with age. This is just a bad roast.

rising coffee prices

There was an article in yesterday's Seattle Times about rising coffee prices and the retail effect. I thought it was interesting for a couple of reasons. First, it quoted Maria at Sweet Maria's:

"People who are interested in home roasting are not necessarily interested in the price," she said. "They're interested in having the best coffee they can have. People who are interested in price go to Costco and buy cheap coffee."

Second, it had a supposed price breakdown of the cost components of a $3 latte: $2.23 for the 300% markup, 32 cents for two shots of espresso, 20 cents for milk, 15 cents for cup, lid, sleeve, and stirrer, and 5 to 10 cents for rent, labor, and utilities.

That last number seems absurd. A single operator would have to produce between 85 and 171 of these an hour just to make Washington state's minimum wage, even if rent and utilities are ignored! When have you ever seen an espresso stand put a car through in 30 seconds, let alone do it all day? The busiest coffee shop I've ever seen is a Starbucks outside the Moscone Convention Center in the morning before an event starts, and I'm sure it doesn't come close to serving that many items per employee per hour. Hmm.

a return to delicious normality

I hadn't roasted coffee for many weeks until yesterday. Tracey won several packages of various Starbucks beans at some event and I've been using those. This morning I made lattes with yesterday's Moka Kadir. Oh, my. What a stunning reminder of why I roast my own! It was like replacing a mud pie with a chocolate soufflé.

first Turkish coffee

I've been wanting to try Turkish coffee (making and drinking) for a long time. A few weeks ago I finally made it to a local Turkish shop, Istanbul Imports, where I bought what is very commonly called an ibrik, but which the proprietor assured me was properly called a cezve. In Turkey an ibrik is something else.

I had a very good stovetop popper moka kadir roast and the simple instructions in Kenneth Davids' Coffee book to follow. I ground the beans at the finest Turkish setting.

For two servings at light sweetness I added four rounded teaspoons of coffee and two teaspoons of sugar to the empty cezve, filled it halfway with water, then stirred to dissolve the sugar.

It went onto a burner at medium heat and in a few minutes boiled. It foamed vigorously to the top, at which point I removed it and poured into demitasse cups. The foam should completely cover the coffee, and there is apparently some art to generating and/or preserving it. I don't think mine was quite right but it doesn't seem like there's that much of a trick to it. I may be missing something. It does diminish rapidly after being taken off the heat.

It was quite tasty. I think this is probably the right sweetness for me, but I'll try it at full sweetness (twice the sugar; thrice for heavy sweet) next time. This is a nice way to get a quick coffee fix without waiting for water to boil or the espresso machine to heat.

Update: I tried again at full sweetness, and also allowed the foam to dissipate and build a few times by removing and restoring the heat, a technique which I read about somewhere. I don't know if that contributed, or if the additional sugar is a factor, but I did get a more durable head. Tracey and I both thought it was very good.

coffee: the world in your cup

Seattle's Burke Museum has had an exhibit running for a couple of months now called Coffee: The World in Your Cup. It was recently extended through September 7, which means that despite my procrastinatory nature I may manage to see it. What I'd really like to do is attend on a weekend for one of the tastings. The Batdorf & Bronson demonstration on May 9 would be interesting:

Green coffee buyer Scott Merle will demonstrate the characteristics of new crop coffees from Central America. Learn how to discern ultimate freshness in this comparative coffee tasting with Olympia specialty coffee roasters Batdorf & Bronson.

If we do Ethiopia as a grubtrotting country the Ethiopian Coffee Ceremony on April 5 or June 7 would be an appropriate augmentation:

Ethiopia's coffee ceremony is an integral part of Ethiopian social and cultural life. But don’t be in a hurry! Ethiopian homage to coffee is sometimes ornate, and always ceremonial. The coffee ceremony takes us back to a time when value was given to conversation and human relations. Sit back and enjoy because it is most definitely not instant.

hot air popper roasting 4

I've been experimenting a bit more with the Popcorn Pumper hot air popper, exploring its heating behavior and maximum temperature and capacity. It can easily exceed 450 degrees (the most I can measure with a compatible thermometer), several minutes of pre-heating will get it there, and behavior changes dramatically based on bean quantity.

With the same beans (classic Italian espresso blend) I've now seen that the difference between roasting two and three ounces is dramatic. With more beans, second crack actually happens, smoke appears, and surface oil becomes evident, all with very little change in roasting time. With three ounces and a preheated popper, 8 minutes will deliver FC or greater.

At four ounces, the popper sounds like it's working a little harder but still moves the beans fine. There's much more vertical action, with beans bouncing nearly all the way up to the opening rather than just swirling. This is the most I've tried, but I think it can handle more as long as the beans aren't being prematurely ejected. Further, this can even reduce the time required to achieve a given roast level.

So my initial ideas were incorrect. Adding beans, not removing them, will increase the temperature and decrease the relative roasting times. It does make sense that the cumulative effect of the exothermic reactions in the individual beans will be greater with higher volume and density. Besides bean quantity and roasting time a significant variable is preheating time. That looks like it might provide a few minutes of control over the total time. Achieving much more control would probably require modification of the popper and/or control over input voltage. Regarding the latter, I do have some crude control given that the dining room and kitchen lights are on the same circuit that I've been using. The dining room will draw 500 watts and the kitchen 450. There's a clear effect on the popper's performance!

On 2009-03-16 I roasted four ounces of Yemen Mokha Sharasi. This is no longer available from Sweet Marias, as far as I can tell. It took only six minutes in the preheated popper to hit a raging second crack and blow off quite a bit of smoke. Roasted weight was 3.2 ounces, or 80% of original.

Not that these tasting notes matter much, since my remaining four ounces are probably all I'll ever have, but they do illustrate a few things.

Shots pulled immediately were horrible. I mean, the worst espresso I've ever had. Overpowering solvent-like flavors. There was improvement after 24 hours, with the raw gasoline flavor abating somewhat. I was unable to detect any of the theoretical fruit flavors, though. After 48 hours it had become quite good, with just a faint solvent edge and noticeable sweetness and fruitiness. It was pretty good straight and very good in a milk drink. Long, mellow aftertaste. After 72 hours, the recommended minimum rest period, it was really nice. No off flavors, some pleasant sharpness, and definite sweet and fruit notes. I would put this into my regular rotation.

So the lessons are that good results certainly are possible with this popper and I shouldn't rush to judge those results.

espresso monkey roasting notes 3

On 2009-02-15 I roasted the last of the Espresso Monkey, only 6.31 ounces, looking for a lighter roast than last time. Very little wind, outdoor temperature 36 degrees F. To have more temperature control I did not use the shroud, and had a steady 525 degrees at 2.5 on the gas control.

I was successful in achieving lower temperatures than last time, and first crack was at about the same time, but progression was much faster with the reduced bean quantity. Second crack overlapped first, and was quite noticeable by 180 seconds, at removal. I ended up with another pretty uneven roast, but lighter overall. More bean mass would definitely help. A half pound or less in the popper just seems too volatile. Final weight was 5.26 ounces (83%).

Pulled two shots a day later. Now this is very interesting. It's almost all high notes, with just a few midtones -- a totally different palate feel and experience. I'll have to do some further tasting to refine my impressions, but there's nothing that I don't like. It's just lacking the deeper chocolate flavors. I used the second shot in a latte and found it to be very sweet and pleasant. It is dramatically different from the recent roast in the hot air popper.

Two more the next day. It seems to have become a little fuller in flavor, with nice body. This was a slower extraction than yesterday, though, so I can't be certain this is a good comparison. But I can say that there are circumstances in which I like this blend quite a bit.

hot air popper roasting 3

Wanting to try the Espresso Monkey at a lighter roast than the stovetop popper roast, and not having tried the hot air popper for a while, I gave it a go this morning with 2.05 ounces and a pre-heated popper.

I heard the first pop at 2:10, then at a rate of one every few seconds at most, often with nothing audible for many seconds at a time. At 6:00 the beans were approximately cinnamon colored, at 7:00 approximately milk chocolate, then I removed at 8:00. There was still an occasional crack and jump in the bowl. Cooled in the freezer for a few minutes. Spreading in a thin layer on a sheet of foil works great.

I certainly got the lighter roast I was looking for. I ended it at the point where I wasn't sure it would get much darker and was concerned that it would just bake into flatness. Roasted weight was 1.69 ounces (82%). Particularly since the quantity is so small I'm going to let this rest until tomorrow before tasting.

Update: After resting for 25 hours I pulled two shots. There's subtle fruitiness and sweetness but with a surprising amount of bitterness as well. It's a somewhat chocolate-like bitterness, but there's also something harsher to it. These may be the "shart unpleasant notes" one is told may be possible if it rests for less than 36 hours. It seems somewhat muted, overall, without the dynamic range I'd expect from the lighter roast. That may be an artifact of the method. I'll be interested to contrast it with the second attempt using the stovetop popper.

Update 2: Another day of rest didn't improve it. The lingering aftertaste has a solvent quality that I dislike.

espresso monkey roasting notes 2

I've roasted a few pounds of Sweet Maria's Espresso Monkey blend and it has never been my favorite. I had a little left, so yesterday thought I'd give it another try. The target roast was Full City.

Outdoor temperature was about 40 degrees F. No wind. Roasted 8 ounces (weighed on new kitchen scale), which is quite a bit less than I usually roast. Beans were initially at room temperature. The roast went very quickly at the lowest gas setting. In these conditions I suspect more beans would be helpful, and I could also try without the shroud. Roasted weight was 6.46 ounces.

Some beans were still at first crack when second had started. I'm starting to question whether I've ever had a noticeable pause between first and second.

The roast looks about right overall, with some small oil droplets evident. I think the intrinsic unevenness of the stovetop method is a problem. It is very difficult, if possible at all, to avoid finishing without some of the beans having a degree of char.

Pulled shots next day. Some acidity, moderate body. Faint sweetness, but it's set against a burnt note that I don't like much. I am not really detecting anything else that I can put a name to. And it's just not that interesting. Sweet Maria's description on the package is:

At Vienna roast, bittersweet chocolate, hints of dark fruit, licorice, a long aftertaste.

I had to look up dark fruit and found a discussion here. I also discovered a bazillion recipes for dark fruit cake. As a flavor descriptor I'm not sure it does much for me. Much more intriguingly evocative and equally helpful would be dark fruit-eating bat.

As roasted, at least, I continue to not like this all that much as a straight shot. Before spending time with Moka Kadir I would probably have ranked Espresso Monkey higher, but not at this point. I'll shoot for a slightly lighter roast next time.

moka kadir roasting notes 5

Decided to take advantage of unchanged weather conditions to roast moka kadir again today. The things that I think did vary are that the roaster may not have had as much residual heat and I roasted slightly less than two cups. The heat dropped quite a bit more quickly than in the earlier roast, I assume due to the former. I didn't wait for a stable starting temperature. I did achieve a lighter roast, albeit one with more evident inconsistency between beans. That may not be a bad thing, really.

Time	Temperature
0	560
30	475
60	410
90	380
120	355
150	350
180	350
210	350
240	350
270	350
300	225
570	110

This is light enough that I'll try it brewed again. These beans never exude much oil, I've noticed.

What I might try next time is a lower stable starting temperature and a little lengthier roast. The second roast was at a starting temperature of 525 and a duration of 360 seconds; I'll give 500 a shot and see how it affects the time. The slower roast also seems to allow the temperature to begin climbing again, which has not been the case in these last two. The high flame in roast three also produced a clear bottom and increase. Something cooler, slower, and more controllable, but short of the ten minute hot air popper time, seems like the next step.

Two shots pulled several hours later weren't bad. Certainly more interesting than the darker roasts. This blend is still not close to being my favorite espresso, though.

2009-01-28 update: I was at last able to directly compare the properly rested roast 4 and roast 5. No contest. The lighter roast produces a far more interesting and satisfying straight shot. There are sweet, fruity notes evident almost immediately, and which linger in a long pleasant aftertaste. There is just a hint of this in the darker roast. Certainly the same stuff, just much less of it. I do think the darker roast works better in milk drinks, though.

moka kadir roasting notes 4

The effect of even a slight breeze on roasting is startling. Today I roasted moka kadir in the stovetop popper in dead calm at 40 degrees, and if anything struggled to keep the temperature down. This was two cups with a starting temperature of about 70 degrees and the gas at the lowest setting.

Time	Temperature
0	560
30	475
60	440
90	400
120	375
150	360
180	350
210	350
240	350
270	355
300	355
330	355
360	250
600	120

Compared to moka kadir roast 3 this was a little slower and lower. I still have not been able to effectively isolate first and second crack with this blend. It was loudly into second when removed, but with first still banging away. It was again darker than I'd intended. (The graph is fudged a bit to make it clear that second crack occurred; that stripe of unblended yellow shouldn't really be there.)

I did manage to measure bean temperature at removal using a candy thermometer. It's pretty slow for this application, but seemed to stabilize at about 250 degrees. That is dramatically lower than the internal bean temperature, which at this stage is theoretically 450 or more. (Internal temperature exceeds roasting vessel temperature because of the exothermic reactions occurring within the beans.) Air cooled in a colander.

Next time I have really got to get it out of there much sooner. How to decide when, when conditions are so variable and the sight/sound cues are so attenuated, is the trick.

hot air popper roasting 2

Roasted one fourth cup instead of one half, with nothing else drawing power on the circuit. I also warmed up the popper for a few minutes before dropping the beans. The behavior was just about identical to the first experiment with respect to sound and smoke (or lack thereof) however it took just 10 minutes to achieve the same bean color.

Pulled two shots after about an hour. The ground coffee aroma is notably better than the 15 minute beans. I thought the flavor was somewhat better as well although it still has a trait that I noticed yesterday: a certain underdone quality. It's a bit like eating a roasted bean plain. It is certainly a little bit more nuanced than the 15 minute roast, but still nothing like the better stovetop roasts. The next thing to try is a stovetop roast to this same degree.

I pulled two shots of yesterday's roast. The underdone flavor has lessened, as has the bitter aftertaste. However, it is still very flat. From these two samples I think I now have a sense of the effect of the long, baking sort of roast.

If Ed is able to roast 3/4 cup in 5 to 7 minutes in a Poppery II then it appears that this Popcorn Pumper may be markedly less capable, although at a sample size of one I would hardly draw any conclusions about the two models. There could also be a voltage difference; I think the acceptable variation for house current can be as high as 20 or more volts. Maybe he'll engage in some poppery swappery for a night and we can compare.

hot air popper roasting

Score! On my occasional visits to the thrift store to buy books I always look for a cheap hot air popcorn popper but have never found one. Yesterday I at last had the long-awaited fortuitous encounter and dug out the $5 bill I've been saving for the occasion.

I am now the owner of a Wear-Ever Popcorn Pumper, seemingly in great condition other than lacking the butter cup.

I read the section on hot air roasting in Davids and dove right in. I roasted the Moka Kadir blend indoors beneath the range hood, at room temperature of about 70 degrees. There was a notable gap between what I expected and what I experienced:

• The smoke, expected at 3 or 4 minutes, did not ever appear.
• First crack did start as expected a bit after 4 minutes, but never increased in frequency and occurred sporadically for the duration of the roast.
• Medium roast was expected at 5 - 6 minutes, medium dark at 7 - 8 minutes, and dark at 9. I shut it down at 15 minutes at about full city or perhaps a bit shy. If any beans were at second crack I couldn't tell.
  

That's a pretty long roast. Probably the beans can be characterized as having baked. I wonder whether the popper was up to the task. I cooled this small quantity in just a few minutes in colander and freezer.

The beans themselves are very clean, with nearly all the chaff being blown off, and the color consistency is very good. Both are much better than what I normally experience with the stovetop popper.

I pulled two shots almost immediately, although this blend is supposed to rest for a couple of days. I have never made espresso with a roast this light, I have never roasted Moka Kadir this light, and this the first time I've used the air popper. I therefore don't have much of a basis for meaningful comparisons. The ground bean aroma was not very intense. The espresso wasn't very good, frankly. The flavors are not nearly as layered or complex as in the second Moka Kadir roast (yesterday's super dark roast can be ignored). There's a lingering bitterness in the aftertaste.

With further experimentation I should figure out what effect the long roast time had. I still want to try Moka Kadir at a full city roast, both as espresso and brew.

There are two obvious things to try next time:

• Reduce the bean quantity. I roasted half a cup, which is the volume of the hopper, but I wonder whether it should be halved.
• Don't put any other load on the circuit. The kitchen lights dim noticeably when an electric griddle or the popper is turned on. I turned the lights off, but well into the roast.

2009-03-19 update: Significantly better results.

moka kadir roasting notes 3

1/10/2009 roasted Moka Kadir blend. I needed coffee, of course, but this roast was also about refining my data collection methods. It ended up being darker than I wanted but I think I learned some things. Recording times on paper while watching a timer worked OK. Forgot to get a bean temperature at removal and the thermometer is too slow for an ideal measurement anyhow.

Outdoor temperature was 46 degrees and it was a bit breezy. Because of the wind I had to use a higher flame to get up to temperature, despite the shroud. I kept it high, around notch 3, and it had a dramatic effect on temperature range and roasting speed. Starting bean temperature was 76 degrees. Roasted two cups.

Time	Temperature
0	550
60	425
120	360
150	355
180	355
210	360
240	370
270	385
290	390
555	120

First crack started at about 120 and was peaking around 240 seconds. I think that second crack and first crack overlapped, with second starting at perhaps 240. There was no clear transition. The roast ended up being pretty solidly in French territory, without any surface oil. Some beans are beyond that, and there are far fewer lighter beans than in the previous roast.

Pulled two shots after 90 minutes with proper timing and quantity. The ground coffee smells great but the flavor is well over-roasted for me. The acidity and bright notes are not present; in fact, almost all interesting traits have been eliminated. I don't think this will be good for anything but milk drinks.

These beans should have been removed much earlier. I should experiment with the differences between a short hot roast and a slower cooler roast. And with the Moka Kadir blend I still want to try a significantly lighter roast than I have achieved so far.

roasting measurement thoughts

As I fool around with measuring time, temperature, and roast progress I am beginning to think a little more about tools and techniques. It's a simple fact that there are some limitations with this roasting hardware with respect to repeatability and fine-grained control. Those are tradeoffs that I accept, because I really enjoy the interactivity and physical engagement. However, there are surely ways to optimize the performance within the constraints of my abilities and tools.

There are three data types I collect or employ: time, temperature, and sensory impressions.

Elapsed time can be recorded accurately. No problem there.

Indicated temperature can be recorded accurately, but what is being measured is the air temperature of the roasting vessel rather than the internal temperature of the beans. I suspect that there is significant variability in the delta between those temperatures. Factors might be bean quantity (volume), bean temperature uniformity, air exchange rate, bean density, roast stage, and surely more. Finding ways to minimize and correct for this variability may be important. Consistent bean quantity is the easiest and most obvious change.

I don't currently have a great way of measuring the starting and ending bean temperature. Troy mentioned how much he likes his Thermapen. That would be a good way to get a speedy reading during cooling. Cooling times are presently quite inconsistent, based on ambient temperature, wind, bean volume, temperature at removal, and cooling technique (colander, roasting pan, mister, freezer, etc.).

Sensory data are bean sound, smoke aroma and volume, and bean color. These are pretty subjective. Bean color can be determined only by opening the lid, which is obviously not free of side effects. Beans are hard to see through the dense smoke. Smoke aroma and volume are easy to observe. Consistency and granularity of the observations is the main challenge. The same is true of sound.

A physical challenge in all of this is the difficulty of recording the data while cranking the popper. An audio recorder would be a big help.

I'm not sure how significant a factor the cranking rate and continuity might be.

Well, I need to cogitate further and devise a plan.

roast grapher

I whipped up a little AppleScript application with XCode and Interface Builder to turn coffee roasting data into a Google Chart. As can be seen from the screen shot, the URLs are quite awkward to construct by hand.

Now with just a few seconds of data entry I have a graph of temperature against time, along with the phases of the roast (red for first crack, orange for second crack, blue for cooling).

I'll see how this works out and modify it accordingly. I think I might have it generate a table with the data as well.