Jim Schulman -- Profile Advice

Jim Schulman's Suggestions for Espresso Blend Roasting

After roasting my first 7 roasts, and floundering with the iRoast, Jim Schulman offered some helpful suggestions, at the Coffee Geek homeroasting forum. I've listed the pith below, and included a visual chart which I hope approximately represents his conception.

ROASTING ADVICE (to accompany chart)

A)   70F-300F Bean Drying 3.5 - 5 min.

B)   300F-390F Up to first crack approx. 2.5 - 3.5 min.

C)   First Crack (FC) start: 385F to 400F.

"The secret of a good roast profile below the first crack's end
is very simple -- the best roast is the fastest roast which keeps
the beans at an even color throughout."

D)   First Crack End -- Varies -- 1-1.5 min. median.

E)   First crack ends.

"I like to spend about 2 to 4 minutes between the end
of the first crack and the end of the roast, no matter how light
or dark I'm roasting. . . .[That is, as well] make the roast finish
4 to 5 minutes from when the 1st crack starts --
if you get a very odd bean or blend, there may be no gap
between the end of the first and start of the second crack.

F)   Second crack occurs anywhere from 400F to 445F.

"If you hate acidity, and like roast tastes, try stopping at
455F to 460F (referring to your bean probe)."

MY Roast 8 iROAST PROFILE
Attempting to match the above:
Stage 1: 320F, 4 minutes (102V-105V)
Stage 2: 410-420F, 3 minutes (115V)
Stage 3: 390F, 8 minutes (110V-115V)
(need to refine this further)

iRoast -- Roast Notes All temps need to be measured by thermocouple.. Very Important.
To accomplish A) above: At the lowest setting of 320F, the iRoast heats beans too quickly. Try 150g (versus 120g) of bean weight, to slow temp. rise. Use voltage control: lower load voltage to 105V-100V. Fan will run at high speed. Note that bean bed thermocouple temperature will read higher than actual bean temp, at the beginning (at a guess, the air temp is hotter than bean temp, the first 0-2 minutes).

Next, to accomplish B) above, time Stage 2 to begin just after your beans reach 300F. I'm using a Stage 2 of 410-420F because it keeps the fan at a relatively high speed (not low anyway), circulating the beans fairly well. I up the voltage, which increases heat a fair amount, and fan-speed a bit. To ramp hotter, try increasing the temp. setpoint. Fine tune with voltage.

Time Stage 3 to begin just as first crack ends. With 150g of beans, I use 390F, which runs the medium-speed fan -- dropping to 385F will run the high-speed fan. To get a full four minutes of time to 455F-460F after first crack, the setpoint can be lowered a bit, 385F-380F (however, your machine may not run as hot as mine-I get a chaff effect, raising temperature); and/or voltage can be lowered. But if voltage is lowered too much the beans will not circulate well. A 390F setpoint at 115V brings my roast to a 460F TC reading in 2:40 from end of first crack - about a 455F bean temp. Full City+ roast, I think.

Another valuable post from Jim Schulman	After endless profiling experiments, I'm fairly sure the main difference between [[air poppers and drum roasters], and it's to the advantage of the drums, is that poppers raise the beans from room temperature to above 300F in about 1 minute, whereas it takes 4 to 7 minutes in a drum. After that, drums roast at the same pace, or maybe even a hair faster. I'm hypothesizing that the fast heat up in poppers means the beans are carrying too much moisture into the roasting temperature region (350+), and this leads to the preservation of chlorigenic acids along with their grassy sour-bitter, sweetness and aroma killing taste. As added evidence, very dry beans, like Yemens and DP Ethiopians, roast wonderfully on poppers, even though they can be very acidic. Based on this, a popper could be modified very cheaply by somebody competent (not me, alas) to produce a high quality roast. The effect of the mod is to create a "low heat switch." The cost would be a 20 amp switch and some heater wire. Add heater wire in series with the existing heater wire to reduce the wattage to about 66% of the original. This will reduce the airflow out of the popper heater to about 350F. The switch would go into the circuit in parallel to the extra wire, so when it is closed, it shorts out the extra winding, and pushes the wattage and heat back up to normal. A variac on the heat alone is an easier but more expensive solution. Operation is simple: run the popper at 350F (temperature of air as it first gets to the beans) until the beans get to 300F, or turn yellow; then hit the switch for normal power until the roast is done. I think this simple mod would get most of the benefit of a PID system. After all my experiments, here's how i run my PIDed roaster -- I blow in 350 air for 4 to 5 minutes, raise it to 500F in the next four minutes, then level out there. How different is that from the simple switch? It probably would take most poppers as long to ramp from 350 to 500 even without the PID.
	-- -- -- -- -- -- -- -- -- Richard G comments welcome. email gilbert(at)iyume(dot)com Return to intro page Go to Roast 8