Roast and Learn Together - May 2015

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
User avatar
Team HB

#1: Post by TomC »

Jim Schulman is going to lead our May RLT. Beans to be announced in the next few days hopefully.
Join us and support Artisan Roasting Software=

User avatar
Team HB

#2: Post by another_jim »

Hi All,

The coffee this time around is SM's Tanzania Pulp Natural Igamba Mpitu Peaberry.

I had my eye on this because it presents some interesting choices for roasters. It's a high grown bourbon; it's also a pulp natural peaberry. So should I go fast or slow, high or low heat?

I just confirmed it as a fun choice. Cupped alongside five other (non-Ethiopian, non-geisha) promising looking offerings, it won easily, coming in between 88 to 90 points in my moderately generous scoring system, using a plain vanilla cupping roast. For a pulp natural, there is an excellent amount of acidity and overall pop, with no hint of the flatness these coffees sometimes have.

I do my cupping roasts a little darker (30 seconds before 1st pops second), a little faster (8 minutes), and a little lower in MET (490F) than currently fashionable. At this level, the malty tastes are apparent in finish, with snappy sweet malic acidity, dried pit fruit, brown sugar, and some smokey complexity at the start. Will a more leisurely roast bring out the malt better? Will a hotter roast bring out the Bourbon character? Let's find out.

There's enough body and sweetness to make it a viable espresso candidate, for those who prefer to roast for the shot.

Have fun, everybody!
Jim Schulman


#3: Post by ccr »

I also found this coffee to be quite interesting. Not sure if anyone else has experienced this, but this bean gobbled up heat like crazy. Not only did it speed through dry and ramp, it almost collapsed into a stall when hitting first crack. Just a heads up.

I'm trying this as a minor component of a pre-roast espresso-intended blend to accent a few Brazils. Pre-blending certainly made the roasting process more controllable.

User avatar
Supporter ♡

#4: Post by Boldjava »

Grabbed some this morning. Friday is May 1st. Order up folks.
LMWDP #339


#5: Post by jalpert »

I roasted two batches today.

This bean had no audible first crack. I don't know what happened. I got a few outlier pops in both roasts at 390F, and then nothing. I assume it's the geometry of the peaberries? These things were pretty round.

The roast also had the most pronounced endothermic flash I've ever seen. I thought it was stalling. Does anyone with more experience have any advice?

Anyway, I think the roasts came out OK. I had no idea what to do with this thing, so I tried two roasts: a typical high-grown Rao style roast, and a roast I've been using on a honey process Nicaragua lately that has good body and depth, with muted acidity.

Roast 1
Huky 500, perforated drum
Charge: 227g
End weight: 198g (12.8% weight loss)
Profile: 3:36/4:10/2:00 (37%/43%/20%)
Drop: 9:45 at 414F BT
Goal: Rao-style declining RoR roast that I use as a starting point for Ethiopias and Kenyas, fairly quick, drop at City to see what properties this bean has. I think I executed pretty well, except for the complete lack of audible FC. By all accounts otherwise, it LOOKS and SMELLS like a City roast, so I assume I got through FC cleanly (????).

Tasting notes: TBD

Roast 2
Huky 500, perforated drum
Charge: 227g
End weight: 195g (14.1% weight loss)
Profile: 4:57/5:01/2:33 (40%/40%/20%)
Drop: 12:31 at 418F BT
Goal: Slow, extended roast. Goal was body and sweetness, which I was hoping the extended maillard phase (per Hoos) and my recent experience with a honey process bean would provide.

I wanted to do a third roast, taking this thing to full city, but the lack of audible 1C made me think twice, so I figured I'd wait for some advice.

Tasting notes: good body, good sweetness, with a bittersweet note. A bit of acidity, but not front and center - more at the rear. Good body, coats the tongue with good finish. The flavor profile is pretty different from most anything I've had. There is a distinct savory, malty flavor. I have no good descriptors for this coffee. No fruit. I like it.

User avatar
Team HB

#6: Post by another_jim »

The second roast looks like the first with the time base stretched, and no change in the proportions. If conventional wisdom is correct, the balance of caramel and Maillard flavors will be much the same, only with muted acidity in the second roast.

Coffee research literature, since it is scientific and based on KISS, uses only one variable to characterize roast profiles: the range from FSSF (fast start, slow finish) to SSFF (slow start, fast finish). You can also conceive these as a bean temperature profile ranging from a straight line for SSFF to a extreme convex curve that stalls at the end of the roast. Finally, if you had a roaster with completely ideal heat transfer characteristics, the SSFF roast would use a linearly rising ET, and the FSSF roast a constant ET at the finish temperature.

Old school drum roasters are close to SSFF; old school air roasters are close to FSSF. With modern controls, most roasters can produce any profile along this spectrum.

The literature suggests that SSFF roasts have more Maillard flavors, less sweetness, and less caramels for a given depth of roast and level of acidity, and that FSSF roasts have less maillard and more caramel sweetness for a given depth of roast and level of acidity. Tom's writeup on this coffee suggests that it would work well at various points along the SSFF to FSSF profile spectrum.

Here are some idealized graphs to help you visualize the way roast profiles are discussed in the scientific literature:

Jim Schulman
★ Helpful


#7: Post by jalpert »

Thanks, Jim, this is helpful.

You're right, the second roast is more or less a stretched version of the first. Frankly I have always (and by always I mean for the 2 years I've been roasting) had a more difficult time producing a SSFF roast. It's quite easy to charge hot, keep the ET more or less constant, and let the BT drift up, making small tweaks as I go. But I find it hard to gain control of FC if my ET is still on the rise when I enter it. I tried a bit to create a more linear relationship between ET and BT in my second roast, but chickened out near FC.

One follow-up question: when using a SSFF profile, does that imply that you must also achieve a higher final temperature? If you are to keep your development ratio at 20% or above, it would seem that a development phase with a higher RoR would mean dropping hotter. In other words, does a SSFF roast necessitate a darker roast?

(PS: I know people argue over whether or not minimum 20% development time is BS or not, so I am looking forward to your answer on this as I think it may enlighten myself and others about the debate).


User avatar
Team HB

#8: Post by another_jim »

Good points.

With a SSFF profile, you will end with a higher MET. If you make this roast as short as a FSSF roast, it will have a huge difference between the internal and surface color of the bean, and a shotgun spread of flavors (this can be interesting in some beans). But the classic FSSF profile is an 8 minute air roast, and the classic SSFF profile is from an unventialted Burns style roaster running around 15 o 20 minutes.

To get an SSFF roast, you need a low drop in temperature and a relatively cool drum on your ET sensor. The heat will then build up slowly in the drum and transfer linearly to the beans. This usually requires cooling the roaster between roasts. You would be aiming a longer roast time, 12 to 15 minutes, rather than the 10 to 12 minutes that the Rao proportions demand.
jalpert wrote:(PS: I know people argue over whether or not minimum 20% development time is BS or not, so I am looking forward to your answer on this as I think it may enlighten myself and others about the debate).
The idea of maintaining the same time ratio for each phase of the roast comes from Scott Rao's book, which may as well be subtitled "one profile to rule them all." If you move between FSSF roasts and SSFF profiled roasts, you must, by mathematical necessity, also vary the proportion of roast times spent at in each phase of the roast.

This week I'll try both styles of roast and give the tasting reports.
Jim Schulman


#9: Post by jalpert »

Excellent, thanks Jim!

One last follow-up if you don't mind: I recently read the Rob Hoos manifesto, and one takeaway there was that the length (in absolute terms) of the maillard phase is important. Theoretically the longer the maillard phase (in minutes), the more insoluble large molecules form, which leads to greater body and mouth-feel.

If this is true, would my second roast really just be a less acidic version of the first? Theoretically the stretched maillard phase also created more body. While I understand that the flavor descriptors will likely be similar, as sweetness will likely be equivalent (since the sugars were allowed to caramelize similarly), I was hoping to create a different drinking experience (lower acid, more body, more chocolaty experience).

I suppose the question from all this is: when dialing in a roast, is the best bang-for-the-buck found in varying between SSFF/FSSF, or varying the overall length of the roast? Clearly there is a good amount of interdependence between the two ideas, but I am trying to understand how to THINK about creating a roast.

Thanks again!



#10: Post by SJM »

I am looking forward to seeing how using the solid drum/fast motor (as opposed to the perforated drum/slow motor) on that HUKY informs the results :-)))