farmroast wrote:I have changed my approach and have been liking the results. Lower and slower ramp to 300f BT. Ending up with a lower ET at 300f BT. At about 285f BT I'm increasing my heat input much more making a steeper ramp 2nd leg but still ending up with about the same ET at 1st crack. I did a city+ roast of Ethiopian Bonko DP and pulled a shot yesterday with the Cremina. Sweet and totally fruit jammy, the lemoniness was just right. By far the cleanest, most balanced, lighter DP roast I've pulled.
cheers,
farm

Ed,
I was just getting ready to start this thread when I saw your post. Nice observation.

I changed my drying phase method from a low charge temperature and slow drying ramp up, to a higher charge temp and faster ramp, hitting 300 degrees at 4 minutes. The results were a poorer tasting roast. The other problem created by the high ET charge and fast drying phase ramp was bean color often seemed to go from a greenish yellow to a light brown without ever hitting bright yellow.

Fullsack wrote:Ed,
I was just getting ready to start this thread when I saw your quote. Nice observation.

I changed my drying phase method from a low charge temperature and slow drying ramp up, to a higher charge temp and faster ramp, hitting 300 degrees at 4 minutes. The results were a poorer tasting roast. The other problem created by the high ET charge and fast drying phase ramp was bean color often seemed to go from a greenish yellow to a light brown without ever hitting bright yellow.

Doug,

Did you see that at all finish roast levels, or were you working at a particular level?

My observations to date have been similar to yours--worse taste with roasts where the initial ramp to 300°F was less than 5 minutes. I think that had me drop the charge temperature about 25°F or so, at least, but I'm not sure as I made the switch just about the time I added thermocouples to the hottop. Previous charge temperatures were based on the hottop display vice an internal thermocouple--which is why I'm not exactly sure.

Chad,
The ideal time for the drying phase is going to be bean specific, the same may go for charge temp. Shorter ramp time for the dryer beans, so I wouldn't use time as a guideline, but rather use the bright yellow bean color. To make the point clearer, I should have stated slower ramp to bright yellow staying under 300 degrees bean temperature.

Depending on bean, my general approach now is the darker the roast the shorter the time to 300f and the higher charge temp. Conserving more moisture for the darker roasts only. Extra drying and lower charge temp. for city+ or lighter

I think drying is both bean and roaster specific. I find DPs need about a minute less, and Indos sometimes a minute more. But that is for my airroaster.

More isn't always better I pushed the drying period to 5:30-6:00 minutes, to yellow and got 2 flat batches of Brazil and sour and grassy Harar and Sumatra. For my roaster, 4:30, 295 degrees is the drying phase sweet spot with these beans. It seems to be the case, even though these beans have different moisture contents. Not sure why that is.

For the charge temp, I changed to 250 from 300 degrees. Maybe a 275 charge will be the ticket.

It would be nice to have a cheap/quick/reliable way of measuring the moisture content of beans. I would think the drying phase would be proportional to the moisture content.

Good point Jim, my assumption harder beans would hold a different moisture content than softer beans is off base. Porosity isn't really the issue.

This has been a great topic. Using an RKDrum, I have not been pre-warming the drum for fear of scorching the greens. But I guess that this will not happen as long as the charge temp is around 300 F. I am also a little cautious because the drum is not spinning while being loaded. However, I will try this for some roasts as I have found that my lighter roasts do taste flat, grassy.....baked? Nowhere near the fruit tastes as others have found.

So, how would this sound for something like Ethiopia Idido Misty Valley:
1# in drum charged to 300F
Proceed back to 300F over 4-5 minutes
Increase heat to start FC at 8 minutes and done by 10 minutes
Continue for about 1 minute for a city+ roast at 435 F bean temp

Any feedback greatly appreciated.

Dave

For flat and baked, a higher drop in and faster roast is good; for grassy (i.e. chlorinated), more drying is called for. If you have both, I'm stumped.

another_jim wrote:It would be nice to have a cheap/quick/reliable way of measuring the moisture content of beans. I would think the drying phase would be proportional to the moisture content.

Without using an expensive meter here is a thought for consideration. Take a small metal container(thinking an espresso basket might work well with the fine holes adding some air flow) that will hold a few grams of green beans(would need to test for best amount). Add some beans and weigh them on a gram scale with a tenth of a gram resolution. Then put the beans in a whirly blade mill and run til fine. Put the powder in the basket and set in toaster oven(or a little oven could be made with a low wattage light bulb) on a lowish temp. Maybe do a couple stirs during drying. Dry the powder and then weigh again. By testing and occasionally weighing the cup you could determine how long it would take. We could test this process by finding a local roaster with a accurate meter and compare using the same green beans. Think this might work?
Ed

Jim et al

You are right. I am getting these flavors in my C to C+ roasts, but not in the same roast. My darker roasts may be covering up these flaws.

I have developed the habit of trying many different coffees rather than trying different roasting methods/profiles and I think this is my downfall.

The general guidelines I have been following are:

Don't stall the roast.
Don't go too quick (e.g. < 10 minutes)
Don't take too long (e.g. > 18 minutes)
Try to have 3-4 minutes between end of first crack and start of second crack.

I guess I am looking for advice on fine tuning roasting profiles for light vs. dark roasts and hard vs. soft beans (high grown=hard?=Kenya/Central America....low grown=Sumatra/Brazil=soft?)

Also, sorry for changing topics, but in my hours of lurking this is one of the first threads which details drying times and charge temps and the effects on flavors.

Thanks, Dave

farmroast wrote:Put the powder in the basket and set in toaster oven Think this might work?
Ed

Good idea! I've done this with roasted coffee to do solids extraction estimates and got about a 3% reduction in weight; so maybe green-ground done the same way (275 oven for 2 hours) will give a moisture content estimate. It doesn't need to be exact, just linearly proportional to the actual moisture content, so one can use the weight loss percent to empirically adjust the drying time ("empirically" means guesstimates based on collected data and past guesstimates -- the usual way we figure out profiles).

David,

Your roast profile sounds good. Maybe the drying time needs an extra minute more for lighter roasts and a minute less for darker.

However, I hope some one who actually uses an RK drum can chime in on this, since I'm just guessing.

Got the stuff setup to do a test. I have some of the first lot of the Brazil Ipanema that some thought seemed dry and have some of a new lot coming tomorrow. Will do 3 baskets of each in Oly Cremina dbl baskets(have 6 the same). Thinking between 10-20grams probably try 15gms. The first lot has been vacuum packed in canning jars and I always have Tom send me beans in ziplocks. Then still thing about 2 other origins to try on a 2nd round. I have the Ethiopia koratie DP and WP? Snaked a thermocouple in and the t. oven is cycling between 250-275f. Never thought I'd be grinding coffee in a whirly blade again

farmroast wrote:Without using an expensive meter here is a thought for consideration. Take a small metal container(thinking an espresso basket might work well with the fine holes adding some air flow) that will hold a few grams of green beans(would need to test for best amount). Add some beans and weigh them on a gram scale with a tenth of a gram resolution. Then put the beans in a whirly blade mill and run til fine. Put the powder in the basket and set in toaster oven(or a little oven could be made with a low wattage light bulb) on a lowish temp. Maybe do a couple stirs during drying. Dry the powder and then weigh again. By testing and occasionally weighing the cup you could determine how long it would take. We could test this process by finding a local roaster with a accurate meter and compare using the same green beans. Think this might work?
Ed

I would recommend weighing the ground beans before and after drying to take away the variability of grounds that don't make it from the grinder to the basket. Then you don't have to be really anal about cleaning out the grinder either.

Just got a chance to do 2 samples. Both were Bali "Blue Krishna" 20.0grams. that just arrived today. Both lost 2.3 grams. They leveled out after about 1 3/4hr. at 250-275f. One was ground kinda fine with some little pieces the other averaged a course french press grind the whirly blade has to work pretty hard but it managed to do the job. Will try the Brazil Ipanema 2 different lots tomorrow. Might consider getting a .01g resolution 50gram scale.

Sounds really good. 2.3/20 is 11.5%, right inside the required 9% to 13%. You expect Indos to be on the moister end, and a DP brazil to be on the dryer, but who knows?

0.1 out of 20 grams gets you to a half percent. The SCAA standard for green is 9% to 13%, so 20 grams divides that range into eight half percent steps, which seems like more than enough for deciding whether to go three to five (for my little airroaster), or 4 to 8 minutes for a big drum roaster.

another_jim wrote:For flat and baked, a higher drop in and faster roast is good; for grassy (i.e. chlorinated), more drying is called for. If you have both, I'm stumped.

I am struggling with this concept, as obvious as the answer may be, it seems there are two ways to get to about 300 degrees in about 4 minutes: a high charge temperature with a lower temperature ramp and a lower charge temperature with a faster ramp temp. Would one way do a better job than the other?

I don't know.

The high drop in, low heat, would get a more convex profile, while the low drop in, high heat would create a more linear rise. The convex profile would have the beans at a higher temperature on average, and so may have slightly more of a drying effect. But whether it would be distinguishable in the cup is another story.

My guess is that there may not be a lot to it (I notice no difference in preheating or not preheating my airroaster, but that's a different animal). If one approach gives a lot more trouble than the other in the subsequent roast, that would be the decider.