I tried my first decaf roast using SM Decaf Donkey Blend. I reduced the heat and tried to keep things from running away (heat gun and bread machine with thermocouple). My thermocouple is always located in the same place, so it should give me a decent relative measure. Here are my roast parameters:

Drying: 5:10 to 300F
Ramp: 4:20 to 1C at 398F
Dev: 2:10
Ended roast at 11:40 and 440F, FC, which is where I typically end for espresso (just before 2C).

The beans looked darker than non-decaf beans, but I was prepared for that. I roasted this stuff 4 days ago, and tried a few shots today. It's pretty sour. I tried, 15g, 14g and 13g in a standard 14g double basket, 30s pour, and even tried running 35s (past blonding). Temp was set at 201F on my Vetrano 2B espresso machine. It's still sour. I didn't expect that. It tastes like a much lighter roast, but I ended at 440F. Wouldn't the external bean temp be approx the same as for regular beans to give me the same level or roast?

Any guidance?

Thx, Lou

Sounds like the center of the beans were still underdeveloped. It's tricky roasting a pre-blended coffee of mixed density. Try to drag out the drying period a bit longer and see how that works. You can try grinding finer, cutting the dose and brewing hotter, but if the roast was a miss, it won't be easily masked by extraction tweaks. It's like putting makeup on a pig.

TomC wrote:It's like putting makeup on a pig.

Dare I ask how you know this?

Alan

I've been stretching my drying phase out to even up to 7min for espresso recently. At 3 1/2 to 5min, I was getting a lot of fruit tartness/sourness, which sometimes was cool and sweet as a 1oz double updosed and pulled slow, but I prefer a more workable range to give me a little more flexibility and control. Adding development time also seemed to give me better results when varying the temperture I dropped at for different flavor profiles

The beans looked darker than non-decaf beans, but I was prepared for that. I roasted this stuff 4 days ago, and tried a few shots today. It's pretty sour. I tried, 15g, 14g and 13g in a standard 14g double basket, 30s pour, and even tried running 35s (past blonding). Temp was set at 201F on my Vetrano 2B espresso machine. It's still sour. I didn't expect that. It tastes like a much lighter roast, but I ended at 440F. Wouldn't the external bean temp be approx the same as for regular beans to give me the same level or roast?

Post by TomC » Wed Mar 11, 2015 1:17 pm

Sounds like the center of the beans were still underdeveloped. It's tricky roasting a pre-blended coffee of mixed density. Try to drag out the drying period a bit longer and see how that works. You can try grinding finer, cutting the dose and brewing hotter, but if the roast was a miss, it won't be easily masked by extraction tweaks.

Thanks, Tom. I cracked a few beans open and the color sure looked nice and even from the outer edge to the center. I pulled a 12 gram dose with a slightly finer grind, and it was a bit better, but it also had 2 days more rest. I agree though, it does taste like it is a lighter roast or slightly underdeveloped. Still a little sour.

Post by thepilgrimsdream » Wed Mar 11, 2015 9:07 pm

I've been stretching my drying phase out to even up to 7min for espresso recently. At 3 1/2 to 5min, I was getting a lot of fruit tartness/sourness, which sometimes was cool and sweet as a 1oz double updosed and pulled slow, but I prefer a more workable range to give me a little more flexibility and control. Adding development time also seemed to give me better results when varying the temperture I dropped at for different flavor profiles

Thanks, Pilgrimsdream. I will definitely try stretching the drying phase and the development phase. Sounds like you are describing what I am getting.

I'm still not sure about temp vs development. My thermocouple is in the same place in every roast and is submerged in the beans, about halfway down, coming in from the side. I like FC for espresso, before 2C, and with my HG/BM setup, I get that at 439-440F. The actual temp may not be accurate, but it seems pretty reliable and repeatable with all the various origins I have roasted so far. But all of them have been regular beans, not decaf.

If 440F gives me Full City with regular beans, shouldn't 440F also give me the same roast level with decaf? (I know the beans will look darker, but shouldn't the roast level be the same if the temp is the same?)

Thanks,

Lou

This is not the best analogy, but think about frying a piece of frozen meat, it may seem done on the outside, but the inside will still be raw and maybe even still a little frozen.

Now think of the development as the time you take to thaw your meat before you cook it, that way it gets done all the way into the middle.

Drip and other brew methods are very forgiving, but espresso is a very intensive brewing method that can really bring certain features out, good and bad.

#7:Unread post by thepilgrimsdream » Thu Mar 12, 2015 9:01 pm

This is not the best analogy, but think about frying a piece of frozen meat, it may seem done on the outside, but the inside will still be raw and maybe even still a little frozen. Now think of the development as the time you take to thaw your meat before you cook it, that way it gets done all the way into the middle.

Drip and other brew methods are very forgiving, but espresso is a very intensive brewing method that can really bring certain features out, good and bad.

Makes sense to me, and it is a good analogy. My regular roasts come out fine with 4-5 min to 300F, 4-5 min more to 1Cs, and 2-3 min development, with an end temp of around 440F for espresso. I used similar timing and temps on my decaf, but it came out sour. Seems to me that the extra processing of decaf beans would weaken the cell walls, making it easier for heat to penetrate to the interior. I'd guess the insides would come up to temp even faster than regular beans. That's pure speculation on my part, and is not based on experience. I've only tried one decaf roast so far.

I will try a longer drying time for my next decaf roast and do my best to stretch out the development time too. Thx.

Lou