edwa wrote:Very nice to see this simply put in B&W. Can I apply these same general timings for 1C and end of roast for Decaf? I've read and seen how much quicker they can roast and find myself erring on the side of ending the roast possibly too soon, or taking to long to get to 1C. I then adjust to darken.
First I'd say that although I tried to give some basic guidelines as regards timing the roast, that none of this is "written in stone," and in the end the proof will be in the roast product. When I wrote the original post I thought about saying something about decaf, but in the end decided to leave it out. Decaf beans are hard to roast. Unless you are someone who can't tolerate caffeine, I'd either avoid roasting decaf when first starting out, or I'd just accept that they will come out less well and tolerate what I got.
As you indicate, decaf roasts faster, it needs less heat overall, and it is harder to get it to "behave" during the roast. Decaf beans, are, after all, "damaged beans," damaged by the decaffeination process. Nothing you do to them will make them "undamaged," and there is zero possibility that you will get as good an end product out of them as you could get from regular beans. They start out dark in color to begin with, and trying to roast them by observing their color as it changes can be very misleading. In addition, decaf green beans have a very short shelf life, two or three months in my experience. I don't bother with decaf anymore, I don't roast it and I don't drink it. But, then, that is just me. If you want to roast decaf I'd suggest becoming competent at roasting regular coffee first, and then afterwards you can start trying to roast decaf, going easy on the heat input and realizing it is going to take some time and experience to master it.
edwa wrote:Another question, and I suppose this is also dependent on machine type and bean, once 1C is hit is there a preferred heat profile for the stage leading to 2C or does it not matter as long as you get to those timings? I'm not sure I've put my question clear enough. An earlier post stated that they ventilated (via open door) for 3 minutes while using a P1 profile. That setting is 100% power for the duration of the roast with his added open door ventilation, compared to say, a profile that lowers the heat to 70 % after 1C has started but isn't ventilated. Is there a temp/internal heat momentum that we want to ride or is it better to allow a cooling and then add more heat? For the sake of this question ignore how quickly you can increase the heat.
I don't think we can generalize across roaster types. What you want to do is to have a relatively constant increase in temperature from the onset of first crack, although during the first part of first crack, where more heat is likely going to be required to keep the roast going, the increase in "bean" temperature will likely be slower. What you don't want to do is to get your 4 or 5 minute interval by stalling the roast for a while during this period and later pushing it to make it finish. Exactly how to go about doing that on your roaster will take some practice and perhaps experimentation.
pallen wrote:So, we have some general guidelines about the roasting process. As has been stated, it takes about 5 minutes to learn these. (although perhaps longer for some of us that get the deer-in-the-headlights look from all the variables and machine-specific details) At this stage, hopefully we are all on the same page about the textbook "ideals". We each have ideas of how to achieve these ideals on our own equipment.
Now, that leaves us with the tedious work of roasting, tasting, adjusting to get to the next level. I can roast and I can taste, but when it comes to adjustments, sometimes I know what to try, other times the adjustments are shots in the dark. This may be another one of those things where there simply very few good general rules, but what would be very helpful is a kind of chart with some guidelines something along the lines of "When you taste X in the cup, this could be caused by Y and corrected by doing Z". For example: When your beans have little flavor and seem flat, this could be caused by a roast that went too long and is "baked". This can be corrected by shortening the roast time.
I know its very difficult to put taste into words that can be universally understood by everyone, but are there some common roasting "faults" to look out for with some well know ways to correct them? I'm not talking about machine-specific corrections, but general things like roast faster, stretch your time to 2nd crack, anticipate the roasts tendency to run away from and reduce heat sooner, etc... I've picked up a few such tidbits here and there in my 8 or 9 years of roasting, but I have never seen a collection of such tips all in one place.
I wish I could answer your questions, but I'm either not smart enough or not experienced as a roaster to even try. Beans that are "baked" are not going to have just one observable defect, and the degree of "baking" is going to impact how marked the defects are. In its mildest form, the coffee is just going to taste flat when you would expect it to be lively, and it is downhill from there to where you started with perfectly good beans and you ended up with something undrinkable.
My approach as a home roaster is to buy the best beans I can get my hands on, and then roast them in a way that I don't ruin them. I'm not trying to add anything into the beans that isn't there to begin with -- I'm just not good enough at roasting to do that, nor do I think that there are very many people who can accomplish that. So, I try to roast "cleanly," to do things gradually, and as much as anything to avoid doing things that I know can diminish the results. There may be some subtle things that a roast master might do that could bring out the best in one sort of bean, then some other subtle things they could do with another sort of beans to bring out their best qualities. I'm just not that good, and I don't think I ever will be. Judging by the quality of many commercial roasts I've tried, most commercial roasters aren't that good at it, either.
What are the things that will, for sure, damage your roast product? They are scorching (by putting the beans into a roaster that is too hot, or by applying way too much heat during the roast); "baking," by letting the roast take way too long to finish, either by a too-slow temperature rise and/or stalling the roast; not allowing enough time for the beans to develop by rushing the period between the onset of 1st crack and the end of the roast; and (in my opinion) by roasting too dark, so dark that you obscure the fine varietal qualities that were present in the beans when you started but that were "charred out of them" at the end by roasting too dark.
I think that if you concentrate more on buying the best beans you can afford, and on avoiding the screwups above, you will go much further towards getting good roast results than you will by focusing on minutia such as small differences in roast curve appearance and other factors that probably won't effect the end results much and may not even be modifiable with your equipment, no matter what your intentions.