Another problem in roasting that may be addressed by profile variation: insufficient glass phase

In the Roasting 101 article, another_jim describes the glass phase thusly:

another_jim wrote:After the halfway point of the first crack, the cellulose cell walls of the beans enter a "glass phase," in other words, they become a gooey liquid that expands as the remaining gasses inside the cells expand. If your roaster cannot reach that temperature, then you end up with very hard, small beans.

From this we can extrapolate that, regardless of roaster type, if you have the symptom of hard, small beans, one of the causes may be insufficient roaster temperature - the roaster generates enough heat to initiate first crack (AKA 1C) (~400°F BT, gathered from various internet sites, including Sweet Maria's visual pictorial guide to the roasting process), but whether by user control or design, doesn't generate enough heat to complete 1C.

To tie this back to the 3 ramps that have been discussed, this would be a problem with the finishing ramp.

-s.

Another consideration for profiling: initial bean mass

This will depend on your roaster's abilities (see a trend here?). I think that the 3 ramps can also apply here, but think that the absolute timing for a 125g roast in an unmodified air popcorn popper may NOT be the same as the timing for a 5lb BBQ drum roaster (i.e. the 9 minute roast in a Poppery vs. an 18 minute roast in an RK drum).

Time ratio may be a better measurement than absolutes in this case.

hmm...

Perhaps we should christen this thread the H-B "Three R's" of roasting

-s.

To expand on the temperature side, I've been wondering about which temperature of the three (bean surface temp, roaster environment temp, exhaust temp) would be most beneficial in profile tweaking, and it seems that again, it will vary with your roaster. What matters more is that, whichever temperature you're using, you're getting repeatable results.

In an earlier post, I gave more weight to temperature than to sight or smell. This was not intended to dismiss the other two, and here is where all three can be used to help triangulate your location within the roast, if you will.

e.g. If you're using a dogbowl a la JimG, and you notice that the beans are turning yellow, but the temp readout is 350°F, then shoot for that EVERY time. If you're smelling wet hay at 382, ditto. 1C at 445°F? Repeat it. When you can hit that note again and again, you can work backwards and tweak (as much as your roast method allows), adding a minute here or taking away a minute there, or adding 5°F per minute per ramp, etc..

-s.

coffee.me wrote:Who's that newbie ?

Might have been me as I mentioned any prospect of roasting 101 a week before and then also asked for one of his profiles... since I have recently finished an air roaster based upon a popper and expected a certain level of transferability where BT is controlled directly.

Thanks for lots of good material so far: agreed that BT is the most important measure and it should be comparable across different roasters with allowances for air/coffee ratio during a roast and also perhaps the depth and frequency of temp cycling of individual beans moving from heat source to bean mass within a roaster during a roast. There must be some way to characterise a roaster... If, like most roasters, there is no direct control over BT then complex recipes to manipulate the controls are required to achieve a given profile. Starts to get messy.

On accidents, certainly learn a lot and perhaps reporting of these and their effects can help others? Gives one hints where to look. I have found doing prohibited stuff such as dropping and oscillating temps are not always damaging.

When documenting a BT profile I use a shorthand say 110-4-150-2-190-1-200-6-230 where by their size, times and temps are obvious (and it is obvious whether F or C by value) add :30 etc to times as well if required, still unambiguous. Just a suggestion. Since my roaster just does what it is told, I only need to note and deviation of PV from SV during a roast.

Still very early days for me - only ~40 roasts done, lots of A/B comps where only 1 thing is changed. Very slow as I can't drink that much coffee.

Eric

Threads like this one, not unlike a lot of threads dealing with espresso machines, have a tendency to become utterly useless when they start to lose all reference to coffee, and they become discussions only of equipment and measurements. Anyone who has roasted coffee for a long enough period will have produced very good roast results by accident, and will also have done what they thought was a good, standard, profile and ended up with burned or otherwise compromised beans. Numbers and graphs can be useful, but they are merely data points and not real "results," with those real results being the roasted coffee. Sometimes one can't even figure out how one screwed up, or why the results came out so well in a fluky situation.

There are quite a few "frustrated engineer" types floating out there in the coffee ether who profess to be interested in coffee or espresso, but who never really talk about coffee as a "gourmet beverage." Rather, it is all about numbers and various electronic gizmos, measurements, and graphs. Taste is somehow superfluous to their own coffee world. I am most assuredly NOT referring to folks like Andy S. and Greg S., both of whom enjoy coffee for what it is, a beverage, but whose technical contributions have been significant.

If this thread is ever to be of any use (and I'm not sure it ever will be), posts lacking any reference to the desired final end point (e.g. the coffee) are simply, clutter. Likewise, hyper roasting-machine-specific posts only dealing with a certain piece of equipment, especially those which have nothing to say about taste, are quite simply, junk.

end of rant.

ken

Ken,

I don't claim to understand your frustration, but I'd count myself among the frustrated "coffee engineer" types. If I grok your post, it's that none of this matters if it can't be applied to the results in the cup. Then again, it could also be interpreted as the HB version of "You kids and your gizmos, get offa my lawn!"

If your intent is the former, I'd completely agree, as I perceive this thread (and others like it) to be similar in goal, and encourage this continued pursuit. The point you make about "Anyone who has roasted coffee for a long enough period will have produced very good roast results by accident" needs to be broken down:

"Very good roast results" are what I(and presumably, the rest of the less experienced roasters who keep asking these questions) am trying to achieve, based on the limitations of my own experience and roasting method. "by accident" is what I'm hoping to avoid through this process of profile tweaking and tasting the results I'm hoping that the most direct result of this thread will be a set of (somewhat) standardized parameters or metrics that can then be applied to a given roasting method in the quest for a consistent and tasty result.

Given your own years experience, would you care to chime in on the information that's been presented thus far?

-s.

Sherman wrote:Ken,

Given your own years experience, would you care to chime in on the information that's been presented thus far?

-s.

Hi Sherman,

I more or less did that in my post from several days ago.

No one who is not intimately familiar with whatever roaster you choose to use, can possibly give you or anyone else an "all purpose profile" that will work on your roaster or for every roaster, for every bean. Such a profile does not exist, so it is wasted effort to look for it.

The best that anyone can do for you (or any other reader) is to try to break the roasting process (or roast cycle) down into its most important constituent parts, and then to give a few tips that would allow the reader to try to learn, from their own experience, why their roasts satisfy or do not satisfy expectations.

These constituent parts are basically (1) roaster charge temperature, (2) the drying phase, (3) the temperature ramp up just before 1st crack starts, (4) 1st crack and the interval before 2nd crack, whether or not you actually enter 2nd before ending the roast, and conceivable then (5) 2nd crack itself if you choose to roast your beans to that level.

I elaborated, or at least gave my opinions, on these phases (except for 2nd crack, which I seldom roast into) in my earlier post on this thread.

All the consumer level roasting devices are very limiting, in that they either roast very small batches, or they deprive you of the ability to really control or monitor what is going on. You can solve the monitoring problem by hacking in a thermocouple, or a better-located thermocouple in cases like the Hottop, however if you can't control the temperature inputs easily you are fighting an uphill battle. For this reason, and with my experience on a totally manual roaster, I'd personally HATE having to roast on most of the consumer roasters, as I would find them totally frustrating. Using most consumer roasters is like trying to cook dinner, but without the ability to control the flame height on your range, or the temperature in your oven. It is really that simple.

So, for me, I'd go with something as manual as possible, like a simple air roaster/popper, or maybe a BBQ grill roaster like the RK. But then, that is me; I like simplicity. If I can't really control it, the temperatures that are being produced automatically aren't all that interesting as I'm mostly a spectator and not a participant in the process. But I digress.

If you are interested in my suggestions, I'd suggest reading my earlier post, which I tried to make as generic as possible, and to not be tied to any one particular roasting device. But for some of these devices, unfortunately, trying to defeat their innate behavior so that they will allow you to roast as you would like to roast, might require more effort than they are worth. In which case I'd just buy a cheap simple air roaster and take advantage of the fact that this sort of device doesn't cost so much that the producers have enough money to spend that they can get in your way, too much, and it is actually easier to roast with them than it is with the more expensive/more automated consumer level roasters.

Hope this helps.

ken

If roaster "A" and roaster "B" can each be configured to drive the bean mass temp (BT) along the same prescribed time/temperature path, to what extent do the beans care, or even know, whether they were roasted in A vs B?

Are they smart enough to know how they were heated?

Or do they only care about the rate at which they changed temperature?

If the variations in air flow and MET from roaster to roaster were relatively less important than BT profile, then a family of device-independent profiles could be developed. Implementing the profiles on a particular roaster then becomes a separate exercise.

Jim

hopefully this will help get this thread back on the right path.....prior to this thread i'd only heard of the glass phase in passing (probably came up in a thread somewhere here), but i never really thought about it.

jim's comment/explanation (as quoted by sherman in this thread) made me wonder about it. i'm really interested in how to achieve this phase correctly in my roasts. also, what is the significance of getting it right when it comes to the final flavor?

up till now, i shoot for a 4-5 min ramp to 300 (though i've never really gotten lower than 5 mins with my roaster), then give it a bit more heat to gain momentum into 1C. when 1C starts i dial back the heat to avoid losing control of the roast. what i'm wondering, is if it might be a smart idea to boost the heat halfway through first to power the glass phase, but not so much as to let the temp go out of control. or maybe its better to not cut the heat until first is slowing?