Roasting Blog: September 2008

We will be hosting a public viewing of the First Presidential Debate next weekend at Black Sheep-

7:00 P.M. Fireside Lounge- big screen T.V. We will be serving appetizers as provided by Volunteers for Obama, and serving our full coffee, tea, and dessert menu as well as our extended lunch menu throughout the event.

And now on the the blog:

As promised, here are some great photos from our last roasting session.

The profiles are really starting to produce consistently delicious results- and we continue to tweak the slope and length of the plane through first crack on the Kenya, Guatemala, and Brazil.
Here are some macro photos of Bean color transformation throughout the Roast. Times and further profile data to follow.

Just through the warming stage- bean temperature- 300

+ 1 minute, 320 degrees

342 degrees

364 degrees, starting to ramp down to first crack. (back off on heat to slow rate of change from +20 per minute to +4-8 per minute depending on bean elevation and density.)

408 degrees, 1st crack +4 minutes +8 minutes in the cooling tray. Beans are deeply mottled and smell clean and vaguely sweet. No baked aroma or discernible roast taste at all.

And here are macro photographs of our Teas- to be used to make our Tea Menu pages.

Ornamental green tea. Three Flower Burst Tea

Lapsang Souchong- a China Black Smoked tea.

Gunung Dempo

100 Monkeys White Tea

Ti Kwan Yin Iron Goddess of Mercy Oolong Tea. Odd name but excellent tea.

Orange Sencha- Green Japanese Sencha flavored with Oranges.

Provence Roobios Blend- delicious with blueberries, etc.

Here is a couple of photos of the Obama volunteers meeting last night, as well as Rosie playing Guitar!
And a couple of Javier's artwork- On Display at the Sheep until October!

New Tea Menu:

We have updated and changed our tea service.
We now offer several five star- higher end fresh crop teas from Teasource-

For the last two years we have been buying our teas loose from Metropolitan Tea of Canada, one of the world's largest tea suppliers- with access to thousands of great teas and very fresh harvest and high quality tea. Our tea-catalog got to be too large- 45 teas! and so a few days ago we removed everything that has started to stale, and invested in new storage tins for our tea and coffee- more precise water temperature control for the bar, and several new crop teas.

Including:

Milk Oolong, a secret recipe delicious cup, smooth beyond smooth.
This extraordinarily unique and rare tea from China has a deliciously sweet aroma. The cup brews up very silky with a lot of texture and a pronounced creamy-buttery-sweet character to the flavor. These leaves will yield many wonderful infusions. Milk is actually used during the processing of this tea. (FROM TEASOURCE)

Okayti 1st Flush Darjeeling FTGFOP1
The leaf is very green, as is typical with 1st flushes, with an execeptionally fresh aroma. The tea steeps up fuller bodied that many 1st flush teas, with just a bit of astringency to balance the fruity muscatel notes that come through the flavor.. This is an exceptional introductory 1st flush Darjeeling.

Kenya Pekoe
This is a lovely high-grown tea with a fantastic spicy, wheaty aroma that brews up a full-bodied, smooth cup with just a hint of juniper berries in the flavor.

Jade Spring Green Tea
A beautiful, handmade, slightly twisted tea leaf from Jiangsu province with a very fresh aroma that steeps up with excellent body and a wonderful layering of flavors: tart, grassy, silky, delicious.

China Black Special
A beautiful, golden-tipped slightly curled black tea. It brews up very hearty, rich, and smooth with a pronounced sweet note, almost caramel like.

And now- back to the Coffee Roasting.

We had a wonderful accident occur yesterday during a couple batches of the Sumatra Lake Tawar.
On the second, the coffee roast spent nearly thirty seconds at the same temperature.
I mean, it hovered within 0.1 degrees for thirty seconds, just at the end of first crack.
Normally this is cause for great panic. Stalling the roast, even for a few seconds, can render it undrinkable, but in this case, compared to our production roast- which finishes at 2.5-3 degree change per 30 seconds at that same point in the roast, it was sweeter, more developed, with greater body and clarity. Strange and wonderful. I went back and roasted a few more batches trying to acheive this same result, and found that there is a delicate balance point just at the end of the roast that can be spun - with very very low heat, only enough to allow the roast to finish out with the heat of its internal reactions-

I'm not explaining this very well, because it involves some complicated math. You have the change of the bean temperature over time, yes. This is the level most roasters are concerned with and no more.
THEN- you have the change of the ambient temperature over time, yes?
THEN- you have the change in the burner output, and the RATE of change of the burner output over time.
THEN- you have the rate of change in the bean temperature over time, which is a function of Burner output AND change in the ambient temperature over time.

It works a little like this-
You add heat to the drum- which heats the coffee somewhat and heats up the space around the coffee somewhat.
How much is the coffee absorbing over time? How much is translated to the drum and surrounding air-space?
We know that quick changes over short periods of time- (40% burner jump in 10 seconds for example) will burn the coffee- called "tipping " or "scorching" or indeed, too much heat- not even over a short time interval, will burn the coffee.

We know that for each coffee there are best- target warmup times and rates that match well with the elevation at which the coffee was grown, and the processing method of the coffee. Elevation, bean type, bean density, time since harvest, these all play important factors in roasting.
Beyond that, there are many, many ways to roast.

Traditional method-
Add heat. See what happens. Start slow end slow.

Traditional Method #2-
Roast everything dark. The darker you roast, the less you taste. Dark roasts are 'safer' that is to say, you aren't going to taste the defects in low-quality coffee as much as you are going to taste the 'roasty' flavor and 'body' of the coffee. I know several roasters who use this as their main roasting method. Yuck. If you drink a cup of coffee and feel like you just smoked three cigarettes, it's time to try a lighter roast.

New method-
Buy better green coffee- buy the most flavorful, delicious coffee available. Charge what it costs. Who wants to drink bad dark roast? Delicious coffee is still very affordable. Invest in a modest brewing setup for at-home for best cost-efficiency. I am happy to provide this and will be selling basic setups within a week or two on our website.
Roasting:
Get out of the way of the coffee-
The coffee is delicious- and should taste that way. Roasts should be tailored to the coffee, not the other way around. We use a gentle warmup- ramping quickly towards first crack, and then taper off before first depending on each coffee- bean size and shape, elevation, etc. A Kenya, or Guatemala, perhaps, will require more finish heat- ramp down later, finish through first crack somewhat aggressively because it takes more heat-surplus to penetrate that particular bean-shape.

Here's a little more on how we approach roasting.
You add a certain amount of heat to a certain batch, already in progress. Does this change ambient temperature? Does this modify/change the RATE of change of the bean temperature? If it does, you have heat surplus or heat defiency. You are changing the curve, yes, but also the area under the curve, the rate of change. Integral calculus is fun, isn't it?

Depending on the size of the surplus, and the change in the surplus over time, the coffee can be pushed or pulled to absorb heat-over time. The only way we really have to measure this is the bean probe- a thermoprobe within the falling bean mass. At best this is a combination of surface temperatures and thermal mass. You have to listen to the cracks and watch color to get a better sense of what is happening internally.

So we keep track of these changes, our fuel additions, we take tiny little very close-up pictures of each roast to notice color and texture. We get Agtron numbers. We measure our Greens for density in a little acrylic box. We cup every day. We sample, and cup, and test, and cup, and test, and cup. We try every coffee on the cupping table, as espresso, and extracted on the Clover.

It is a dense process, and you build on your knowledge of each coffee over time.

Let's see one particularly successful profile from the last week-

That magical Tawar Batch

Drop 395' Batch Size 5# Diedrich Ir-7
Time Burner Bean Ambient Notes
.5
1 45% 175.7
1.15 55 172
1.30 60 172.8
1.45 65 177
2
2.15 75 191 560 Target for warmup was ambient 550-585 and 14deg/30secd rise.
2.30 75 198.2 568
2.45
3 75 214 580
3.5 74 231 590
4 246.6 595
4.5 72 260 600 We have acheived our max slope and are tapering off to the plane.
5 71 275.5 607
5.5
6 78 298.6 Extra heat is added to compensate for jump in heat absorption at 300-
6.5 80 and airflow change.
7 322 602
7.5 84% 333 609 Heat surplus is restored, and coffee has hit target rise of 10-12 deg/30 sec
8 89% 344 616
8.5 353 621 very beginning of plane out.
9 91% 363.4 624 hot burner, hot drum, hot air, and coffee is still slwing(absorption increases dramatically before the explosive first crack.)
9.5 18% (tapered) 382.7 594
10 15% 389 557
10.5 393
11 18% 395.1 531 holy slowdown batman!
11.5 22% 395.4 514 Whoa! Looking like mulch, but Wait!
12 28% 395.5 529 Ambient is climbing, so we wait.
12.5 35% 396.7 538
13 33% 399.1 544 --Could be interesting...
13.5 36% 402.5 545
14 32% 405.8 545 Drop

1st Crack 10:15
Rolling 11:00 (wow)
Done 13:30
Drop 14:05
DROP 14:05 405.8 degrees F.

Okay, today was pretty dense. Next time will be lots of photos again. ha.