tekomino wrote:What does this to the taste, care to elaborate? Why is it really important to stretch it that much?

I believe it is possible that some roasters, such as the smallest air roasters, may not be able to have their interval between onset 1st Crack and the end of the roast extended beyond 3.5 minutes. This probably will help explain why their roast product may not be very good for espresso.

For me, it is an empirical observation that one needs a relatively long interval between the onset of 1st crack and the end of the roast. I cannot explain to you the exact physical or chemical reasons for this, although it would certainly fit under the topic of "bean development" as this term is often used. Presumably it ensures that the entire bean, from center to periphery, is evenly roasted.

I made this empirical observation for myself several years ago when Jim Schulman and I blind tasted paired shots made from the same coffee that had been roasted to two similar profiles, differing only in the time interval between onset 1st Crack and the end of the roast. I have spent 20 minutes searching here and I can't find the thread where we posted that experiment, but perhaps someone else can find it. It must be buried somewhere in a long thread dealing with something else. One coffee had an interval of 2.5 minutes, and the other had 4 minutes, if my memory is correct. After a number of pairings, it became obvious that both of us could tell the difference in the shots 100% of the time, on blind tasting, and that we strongly preferred the coffee with the longer interval, finding the shorter interval to have produced "flat tasting" shots.

In the interim I have expanded that interval a bit, and now it often extends to 5 minutes (although no more) in my roasts. Exactly what constitutes the absolute minimum time you can have as an interval, and still produce lively espresso, I do not know, but I do know that 2.5 minutes is not enough.

ken

Ken Fox wrote:I believe it is possible that some roasters, such as the smallest air roasters, may not be able to have their interval between onset 1st Crack and the end of the roast extended beyond 3.5 minutes. This probably will help explain why their roast product may not be very good for espresso.

I never liked output of these so that might explain it. They always tasted "flat" and "dead" to me.

Ken Fox wrote:Exactly what constitutes the absolute minimum time you can have as an interval, and still produce lively espresso, I do not know, but I do know that 2.5 minutes is not enough.

That is very helpful. I manage 2.5 - 3 minutes between 1st and 2nd finishing at ~15 minutes total, roasts are acceptable but still not what I think they could be. I know where to improve now. I'll get that stretched so I get 11 minutes for end of first and 15 start of second crack and see what I get. Thank you.

The length between the onset of the first crack and second crack is not really the issue in this thread, although it's pretty clear you want at least a minute more for espresso than for brewing, and longer than that if the espresso is light (i.e the lighter the espresso roast, the longer you want to go after the first crack).

The problem is the end of the first crack running into the beginning of the second. One way to solve this problem is with precise roast measurements. The simpler way to solve this problem is to realize this only happens in a bad roast, when the ramp up to the first has been too long, and the coffee has been baked.

So I'm going back to my original post here which nobody seems to have read -- this is not a problem that can be satisfactorily solved with better thermometers, but with preheating longer and roasting faster up to the first crack. The built-in profile in the older Hottops was fairly close to a bake and definitely needed to be goosed; no idea how the new ones do.