At the suggestion of @tompoland , here are some of the some of the things that have worked (and haven’t) as I have worked to dial in decaf espresso beans. I’d love to hear what works for you (and doesn’t). Many are obvious, for both decaf and caf beans:
I have a “go to” decaf bean, roasted by Goldstar here in Toronto, that is ⅔ Hawaiian Kona and ⅓ “espresso blend”. It is a Full City+ roast, bordering on Vienna. I’d call is a medium-dark. Their product is consistently good.
This bean did not do well with my Eureka Mignon grinder and its flat burr set. I could not dial it in to the taste that I had with my prior heavily modded Bartaza Sette 270 (which included a dimmer mod that allowed some extent of pressure profiling, along with other mods). When I sold my Mignon and bought my Niche Zero, I was (after much trial and error) able to dial this bean in to produce a very tasty espresso, that I take as a cappuccino. I suspect that the NZ’s conical burr set is much more suited to this Full City + roast, decaf bean.
My best shots with this bean were and continue to consistently be 18.0 in (in an 18g IMS basket) and 31.5 out, at 96C, 9 BAR pressure, 16 second bloom pre-infusion and 11.0 grind on my NZ, pouring in 35 to 40 seconds. I have tried longer and shorter brew ratios, coarser and finer grinds, and higher and lower temps. This recipe seems to work best.
I have another bean that I like, which is roasted by Milano Coffee from Vancouver. They call it their Harmony blend and are not specific about its origins. But it is a Vienna roast. Again, I just could not dial in this roast with my Eureka Mignon, but was able to with my NZ. My best shot was/is 18.0 in, 24.6 out at a 10.5 grind with 20 seconds of bloom pre-infusion; 97C. Again, I was able to dial it in with my earlier Sette 270, then not at all with my Eureka Mignon and again now (and even better) with my NZ.
My takeaway is that medium/dark decafs (say Full City to Full City+) seem to work well with at a brew ratio in and around 1:1.75. Somewhat darker roasts (say Vienna) potentially do better with shorter ratios, say at 1:1.35. Long bloom pre-infusions (16 to 20 seconds) seem to help; steam pre-infusions do not. Surprisingly, higher temps seem to be needed for sufficient extraction. I am betting that higher pressures might help, but I have an OPV valve issue on my Lelit E that my retailer will fix, when I bring it in next week.
The other key items pertain to both decaf and caf: 1) a quality basket (for me, the 18g IMS basket), 2) the right burr set for the right bean, which for my preferred medium dark to dark beans seems to be the NZ conical burr set (and its design), 3) careful deep/mid/surface WDT, with four 0.35mm needles (I encountered problems with smaller needles or more needles), 4) a well fitted tamper, which for my IMS basket is the EazyTamp with a 58.5mm base, 5) for the Lelit E, the stock screen seems to work better than a IMS screen. FYI, I personally encountered distribution challenges using the NZ cup. I now grind straight into the IMS basket with a dosing collar, all sitting on a block of wood. I rotate the basket to improve distribution evenness.
My challenge is dialing in a medium light roast (City to Full City). I’ve never been enamored with the flavours of these roasts in decaf beans, but I have and continue to be hopeful to extract good flavours and tastes. The best tastes I’ve had were at 18.0 in, 30.5 out, a much finer grind (8.0), 20 second steam pre-infusion, 97C. I do not like a longer ratio, as I do not like the thinner body/strength that I get from longer ratios. I want it all: sufficient body/strength, good flavours and long length. I just can’t seem to obtain this with a City or Full City roast decaf bean, never mind something lighter. Any suggestions from other decaf espresso drinkers, on how to dial in the City or Full City beans?
Overall, it is most challenging to find good tasting decaf beans. Most roasters carry one or at most 2 decaf varieties. Many just do not know how to roast decaf. Some over roast. I had high hopes for a locally roasted CO2 decaf process bean; it was an “espresso roast” that was burnt to a crisp.
What’s been your experience with decaf? Can roasters actually produce decent decaf, or am I stuck in decaf hell for my remaining years? How do you coax decent taste out of your decaf, especially from medium roast beans?