Before I started roasting I would generally judge a cup by how much I generally liked it. I then found origins and roast degree differences. After starting to roast my own I learned about the need to sort out the flavors in the cup and then to finer sort between the flavors in the bean and flavors due to my roast profile. Now I consider generally 4 arts/science to the process. The art of choosing the beans (Tom at SM makes this easier by getting familiar with his notes), the art of learning to control my roaster and the art of distinguishing the cup, the art of adjusting from what I distinguish. None of theses arts have come easy. When we try to help each other and especially with someone just starting out to tune their profiles, the cup analysis is the best as our numbers tend to be too roaster specific to analyze with much precision. Of course for a beginner the numbers are easier to post and are often what we see first. Then the reply is "but what are you finding in the cup? Is it grassy, bready, sour,sweet,bitter, flat, bright etc. Is there something missing that you expected to find?" I still struggle to be able to detect the roast profile effects in the cup. And the better I get at roasting the finer my abilities to sort these out must become. This becomes even more complicated by needing to understand that some beans are going to naturally have similar flavors to profile flavors more than others. Max just did a roast test to copy a roasting extremes process that Tom at SM just did with his roast comparison offerings "Sweet Maria's Roast Coffee Pairing #15: Same Coffee, Two Roasts". An exercise that should help to sort out roasting approach difference, and should help to more clearly distinguish the extremes and effects.
Can we work out some ways to to be better able to separate tastes like grassiness that I still am not sure I really have a clear sense of its taste or could accurately convey the degree of? Things like why Tom chose the the bean he did for his 12 vs 20 min. roast comparison? So if I wanted to best learn what grassiness really tastes like would there be a better bean and profile to most clearly separate this flavor?

A really fast drying period should produce a grassy coffee.

To me, grassy means a really cutting aroma -- bleach, swimming pool, or fresh cut grass, like sitting around an over chlorinated pool in the summer. It's not really unpleasant, and a little can add a sort of structural astringency, but a lot of it kills off everything else.

IMO, East African coffees are the most astringent or at least prima-donna-ish in this regard. Under dry a light roast, and it can be really bleachy, over dry a darker roast, and it can be really tannic.

I've been searching for a very light roast without grassiness, so if I may, I'll add a taste comparison to Jim's list. For those of you who drink milk in your coffee (as I do sometimes), you may have noticed that some brands of milk will impart a grassiness, even to a dark roast. This milk-grassiness is very similar (to my palate at least) to the sort of grassiness a light roast has when it hasn't spent enough time drying.

What makes ~300F the right drying temperature? What problems, if any, would be caused by a longish drying at very low temperature, say 200F?

The 300F is a boundary marker, since this is the temperature where Maillard browning starts. I'm not even sure the term "drying phase" for the roast prior to that is entirely correct. If it is, then a lower temperature for a longer time should work fine.

If another objective is to get the bean to an even temperature, from center to edge, at around 300F, prior to ramping up the heat, then a lower, longer drying phase would yield a different taste. The roasting chapter in Illy talks about a vapor front that issues from the high pressure center of the bean and makes its way outward as the bean heat towards the first crack. The passage is somewhat beyond me, but I believe it states if the center is too cool, it can remain moist and raw until beyind the first crack. That would not be good for a light roast (may be just the ticket for a dark one though)

I remember hearing some time back that too high a surface temp. early can inhibit the outward flow of moisture. Maybe it's possible to do something roughly similar to searing meat by too much heat early.

I like the searing meat metaphor from a coffee roasting standpoint, but I hate it from a food scientist standpoint (I'd like to apologize in advance to everyone rolling there eyes out there, but I've just got to do this):

Searing meat does NOT "seal in the juices." It's just not something that happens. The muscle fibers exist in such a way that moisture is always able to freely flow in the meat. Now, after resting (off the grill), there is a sort of equilibrium point reached where the cooler juices in that are in the rarer, interior portion will distribute themselves over the course of a few minutes into areas that had lost their moisture, but that doesn't mean that the high heat "locked the juices in." The real reason to sear meat is to create caramelization and the more complex flavors associated with that chemical reaction.

Again, I'm terribly sorry, but my OCD is acting up again. (Now, back to flipping this switch on and off the requisite 17 times.)

Glad someone brought up the meat searing analogy.

I always wondered why pan frying meat in different materials, as in cast iron vs stainless steel, tastes different. The browning is also different. I assumed it is due to the heat conduction difference of the pans, therefore the rate of formation of the melanoidins at the surface of the meat, and therefore the flavor. Could this be a similar reason of the coffee taste differences when roasted in different drum material, like the cast iron drum in the pro roaster, vs the Hottop stainless steel?

As a side note, I also realized that one common lab test to measure glucose control in diabetes, hemoglobin A1c, is a Mallard reaction product. Perhaps biological aging is also caused by an irreversible, slow Mallard reaction?

chang00 wrote:I always wondered why pan frying meat in different materials, as in cast iron vs stainless steel, tastes different.

Cast iron is more chemically reactive than stainless steel. This is why a common piece of advice is to never cook tomatoes in a cast iron pan. The flavor difference that you experience is most likely due to:

1. A result of this greater reactivity, especially if your protein of choice is marinated in some acidic solution,
2. Flavors imparted by the oil or fat used to season the cast iron pan, or
3. A sign that you need to clean your pans more thoroughly.

maxwellh wrote:Searing meat does NOT "seal in the juices." It's just not something that happens.

+1

-s.