Roasting for Rustic Sweetness
I've been thinking about coffees that take a little more work in the roaster - coffees that many of the coffee folk these days who are more interested in brighter and more acidic coffees frequently dismiss. The most clear examples of this are coffees from Sumatra. They're long considered the gateway coffees for consumers who are more used to strong, darker roasted coffees. These are not pristine floral and citrusy coffees. They are earthy, heavy, dry, woodsy, herbaceous, and their acidity is not sparkling. These are coffees that you roast not to push acidity, but to push their rustic sweetness and mouthfeel.
How do I best describe rustic sweetness? Generally it's a quality in coffee that can be quite polarizing because many of these coffees wouldn't be considered to have fully clean cups and also have muddled qualities in general. Rustic sweetness can have nutty characteristics to it like almond and walnut, but can also be herbaceous or rooty with a somewhat cola or root beer-like sweetness. There can also be a bit of aromatic woodiness to them, which is one thing specifically that makes them polarizing. Specialty Coffee origins that I most associate with producing rustically sweet profiles are: Brazil, Sumatra, Sulawesi, India, Yemen, and Java. Some dry processed and pulped-natural coffees will fit this bill as well.
What is their value in the spectrum of specialty coffee? For starters, these coffees tend to have exceptionally complex body/mouthfeel. Also, these coffees are very distinctive and have quite the following among coffee drinkers, and when there is great care taken in their production, they result in a fantastic cup. They tend to handle a deeper roast profile, and in many cases are much better taken into the Full City range. The rustic qualities are accentuated by more caramelization, and often pair nicely with just a bit of roasty character.
Getting the best out of these coffees is a lot more than just deeper or darker roasting though. It really is about development at every stage of the roast. Slow and steady throughout. One of the main side effects of stretching out the roast at any point is reducing the acidity and brightness. Because the acidity in these coffees tends to be a little 'sharp' adding an edge to the cup, reducing that as much as possible is going to help the sweetness come through and even refine some of the mulch character into more pleasant herb-like notes like basil or thyme.
Vespa Central, Java
In looking at how to approach these coffees in the roaster, I did 3 roasts of a Sumatra that we consider to be on the "clean" side of the Sumatra profile spectrum, but one that also maintains a good deal of the rustic attributes we're talking about. I did a standard sample roast development-wise, taking it to a City+ level, and another roast with the same profile but taken into Full City. Then I did a stretched roast where I added about a minute of time to the drying phase as well as some time post First Crack, dropping the roast finally at a Full City level. The notes are as follows:
1. Sample City - Bright ashy-earthiness dry fragrance, slight honey sweet behind bright note on the break. Rough, sharp, lemongrass and woody, and tarter as cools with a lot of grittiness. More citric than green grape tart. harsh cup.
2. Sample Full City - More earthy dry fragrance, darker raw honey, sweet but more earth on the break. Much much sweeter than the City roast, but still some rough material in the middle of the pallet. The syrupy root beer finish is nice. Some of the harshness mellows, but so does the sweetness
3. Stretched Drying and post 1st Crack Full City - The aroma on the beans themselves is all honey on toast, really sweet and enticing. Bready, pumpernickel dry fragrance, sweet molasses break. Deep, sweet, soft, round. Lots of dark malty character and sweetness, very bready. More and more green grape as it cools, sweet honey finish, soft Sumatra character just at the front of the palate.
So you see, adding this development throughout the roast is really important in breaking down these harsher elements. Even though the roast level on the 2nd sample added a good deal of sweetness, the rough characteristics are still present. But you can reduce these, not eliminate them, and break them down so that they're more complementary with the rustic sweetness.