Tuesday, December 16, 2014

First roasts with new BBQ Drum Coffee Roaster

This was going to be a private coffee roasting log, at first (for my own future information, capturing the learning curve for my new coffee roasting cylinder), but... well... let's just say the experience transcended my ability to not share.


Coffee Roasting Log

1st roast with new drum

Type of Coffee:  CoopeDota Café Hermosa
Green beans:  1000g
Roasted beans:  750g?  ish? 
Starting Temp:  550°F

New Tel-Tru grill thermometer doesn't fit existing hole (too narrow).  Also, the stem is so long, it scrapes the drum.  Will try using a couple washers and nuts to adjust it (later).  Active part of the stem is marked by a groove.  No time to mess with that today.  Must roast coffee!

Summary:  First roast was a somewhat mitigated disaster.

Factory rotisserie motor only spins at 2 RPM.  For an even roast, I need more like 45RPM, with an ABSOLUTE MINIMUM of 6.  After much calculation and running numbers on torque requirements, I decide to use our hammer drill at low speed to turn the spit (it has much torque). Long story short... FAIL.  Hammer Drill does NOT like to go slow.  Nothing was damaged but my pride. 

With empty cylinder, I could ALMOST get it stable, using a velcro strap around the trigger.  As soon as I added the load of 1kg of coffee, though, all subtlety was lost.

At low trigger, drill would either not spin at all, or would accelerate beyond a useful RPM*. Coffee got heated un-uniformly, so I pulled it after a couple minutes.  

(*this is my subtle way of saying I almost broke my grill when I tried to take off the velcro strap and accidentally squeezed the trigger, causing everything to basically explode into rapid, panic-inducing motion... causing things to literally fly off the handle.  It is a testament to using well-made, durable machinery, that all is well). 

I decided to try again the next day, so as not to waste 1kg of coffee.  Pre-heated grill to 550°F, as suggested for this size drum.   Added coffee in.  This is a pain.  The cylinder is probably meant to load vertically.  Loading it horizontally, I make an unholy mess and loose lots of beans into the bottom of the grill.

Using a pair of vice-grips as a handle on the rotisserie spit works surprisingly well for manual spinning.  Certainly less traumatic than the hammer drill experience (hey, at least I remembered to turn the hammer function off last time).

5:00 into roast:  Everything inside the grill has caught fire.

OK, on further inspection, this does not include the coffee in the cylinder, but that's a subtle distinction at this point, since it is equally engulfed in flames.  This is probably a sub-optimal roast profile.  I back off the heat a little.

This is a good reminder to clean my grill before roasting.  Especially after roasting chicken.

I end up having to turn the gas off periodically to keep the overall internal temp from spiking out of control.

Later on, after reading more, saw that the starting temp was too high anyway for a half-loaded cylinder.  Not sure how trustworthy the factory grill thermometer is to begin with, but in any case, it was way too hot.  Next time I'll pre-heat to 500°F.  Also, next time, I'll clean the grill thoroughly before starting.

Whole thing was over in 12 minutes.  2nd crack started before 1st crack was done.  Was not at all clear when that started.  Since there are so many beans, the 2nd crack sound is going to be challenging to isolate.  Going to have to work more with times and temp control, once I get those dialed in with the new kit.

At about 12:30, could tell that I had a rolling 2nd crack going (clear sounds of oil boiling).  Figured I had probably nuked the coffee beyond all recognition.  Dumped it.  Definitely WAY over-roasted, but still technically in the realm of coffee, and not quite charcoal. (and still better than Café Avestruz).


Type of Coffee:  CoopeDota Café Hermosa
Green beans:  1002g
Roasted beans: 0g
Loss:  0
Starting Temp:  Nope

Cleaned grill thoroughly.  Was worse than I had imagined it was.  Ick. I'm embarrassed, but whatever, it's clean now.  Pre-heat grill.  Grill doesn't hit 400°F.  Ah.  Low gas.  Great.  Try again tomorrow.


Type of Coffee:  CoopeDota Café Hermosa
Green beans:  1002g
Roasted beans: 887g
Loss:  11.3%
Starting Temp:  500°F

Pre-heated cylinder, then took it OUT to load, vertically.  This is easier without a drill attached.  Conveniently, our patio table even has a hole in it just right for holding the spit and keeping things stable.  This is living.  It's like I planned it.

Temp dropped to about 450°F when I put everything back in.

Time to first crack starting en masse:  12:30
Temp now back up to 500°F

Second crack:  started around 16:50, I think, 
Stopped roast:  about 17:00 (forgot to check clock)

There was no significant time gap after the 1st crack, so the 2nd crack was in full swing when I pulled it.

Coffee came out INCREDIBLY uniform, compared to previous Whirley Pop roasts.

Roast color looks good to me.  Flavor seems a bit light, but I've been drinking burnt coffee the last week.  Also, it's less than 24 hours after roast, and my mom made it, so I didn't have control (or know how long the grinds soaked for).  Tomorrow will tell more definitively, but even today, the coffee is MUCH better than that over-roasted, charred, Starbucks-esque nonsense I've been drinking this past week.

That'll do, pig.  That'll do.

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