Fluid Bed vs Radiant - different coffee taste?

[Bertie Doe]

Hi there, I'm a newbie, I have a Silvia and an Iberital grinder. In the Summer, I'll probably be asking questions about PIDing, or upgrades, twins v hx, rotary and vibes etc, etc. My immediate concern is that my small fluid air roaster is getting a bit noisy, but heck, after 200+ roasts, it's more than paid for itself.
I've heard it said, that fluid bed brings out the best in aged beans. Over time, I've collected together a group of fav Ethiopians, Sumatrans and one or two Centrals. I prefer to take these to Lite French.
If I upgrade to one of the half pound drum capacity radiant roasters, will I need to start searching again for new origins?
I know that questions on taste are the trickiest ones to answer, but I would appreciate info from anyone who has gone from fluid to radiant and (in general terms) has found improvement or otherwise, in their favs. Thanks

[another_jim]

The large industrial roasters, who use low end beans, have very hi tech roasters. In general, these are hot air (convection) style roasters that roast similar to fluid bed ones; however, for their espresso blends, many use radiant heat to finish the roast. I'm not sure if this has anything to do with taste, or just to add the surface char and oil their customers expect.

I'm not sure what advice to give, since I've become fairly agnostic. I use fluid bed, and have a ton of controls, since great roasts on a fluid beds require precise profiles. Drum roasters seem to produce great roasts with a lot less science and a lot more intuition. Some people simply use a heatgun and a bowl, heating the beans with the gun in one hand, and stirring them with a spoon in the other. By my fluid bed standards, this should produce a completely undrinkable roast; however, when done by skilled people, the roasts are quite delicious instead.

As to models, here's my two cents: There's been a few radiant drum roasters on the market, and these have suffered from reliability and spares problems. Purpose built hot air roasters like the Hearthware or Rosto produce the worst coffee of all roasting devices I'm familiar with, and they don't last long either -- they don't have enough control in their stock configuration. The Hottop home drum roaster out of Taiwan is very good; the Gene roaster out of Korea roasts flat. The best roasts I get are from people who've built their own roasters adding drums to outdoor BBQs, PID controls to popcorn poppers, convection ovens, or the aforementioned heatguns. However, this may be because people who do this are more dedicated to the craft.

There's a forum specializing on home roasting
http://homeroasters.org/index.htm
Which has a forum and some pics of homebuilt roasters.

[Bertie Doe]

Thanks for that Jim, I'm not much of a DIYer when it comes to electrics, so will prob go for a purpose-built unit and buy a heatgun for emergency backup. The appeal of roasting 3x3 oz batches in a cold garage is wearing thin, so the half pound batch sizes of the Gene and Hottop is attractive.
I don't know if Hottop owners reading this will agree, I'm guessing here, but does the Hottop's ability to add beans during the roast, give it an advantage when it comes to blending? Can you start a roast with 2x3 oz and then another 3oz later, of a variety that requires a 2min shorter roast?

[another_jim]

Actually, the big DIY for indoor roasting is not the roaster, but finding a window and rigging up an exhaust system. It helps a lot if you can set up a permanent roasting spot by an unused window; otherwise, I recommend putting everything on a wheeled cart.

[lparsons21]

I don't know if Hottop owners reading this will agree, I'm guessing here, but does the Hottop's ability to add beans during the roast, give it an advantage when it comes to blending? Can you start a roast with 2x3 oz and then another 3oz later, of a variety that requires a 2min shorter roast?

I looked at both the Hottop and the Gene and decided on the Gene because you can control both temp and time, and it can roast different quantities. I thought it was the only one that really allowed that.

[Abe Carmeli]

The problem with the Gene roaster is its cooling time. It cools the beans in the same chamber they were roasted, and cooling may take 6 to 10 minutes depending on ambient temperature. This is why Jim mentioned the flat taste of its roasts. It bakes the beans, and also adds an ashy note to it. The only way to overcome that design flaw is to get a separate cooling pan, home made or purchased and dump the beans there immediately at the end of the roast. Something like this Cooling Pan.

[lparsons21]

Yes, I'm aware of the cooling issue. And the Hottop certainly does a better job of it than does the Gene.

But I already do cooling 'cause neither the FreshRoast or Zach & Danis does a very good job. I use a hair dryer and a solid and mesh colander. Seems to do a pretty darn good job.

Unfortunately, every commercial home roaster has some problem or the other. For me, the Gene, with its variable batch size was just the right thing.

[another_jim]

The problem with the Gene roaster is its cooling time. It cools the beans in the same chamber they were roasted, and cooling may take 6 to 10 minutes depending on ambient temperature. This is why Jim mentioned the flat taste of its roasts. It bakes the beans, and also adds an ashy note to it. The only way to overcome that design flaw is to get a separate cooling pan, home made or purchased and dump the beans there immediately at the end of the roast. Something like this Cooling Pan.

Did you get good roasts with it once you manually cooled? The one you sent cooled in the chamber tasted very sad.

[Abe Carmeli]

Did you get good roasts with it once you manually cooled? The one you sent cooled in the chamber tasted very sad.

I didn't. I sent the roaster to Lino, and I believe he fabricated his own cooling device.

[cafeIKE]

I can say as a user of HotTop and Fresh Roast, both moderately modified, that both are capable of making excellent coffee. I've not had to change my stash varieties since I switched to the HotTop from HWP via iRoar and Bravi a year back. My answer is not definitive because I'd modified the FR, HWP and have modified the HotTop to enable more control. IMO, the iRoar and Bravi were beyond redemption.

Not sure if there is any mileage in adding beans mid roast to a HotTop. Never tried it, but roasts done by inserting beans at high temperatures have been less than exciting. There's also the issue of letting out a good deal of hot air. This will tend to cool the beans as will contact with the cold newly inserted beans. Might be Nirvana...

I use a small desktop fan next to the HotTop to cool the beans to room temp in just under 4 minutes.

I've not used the GenCafe, but have a friend who has, and is quite a DIY'r and he is not overly enthused with it. A HotTop that get's dumped for the new 'programmable' model maybe in his future.

Of all the home roasters used, the HotTop is top of the list, even in its stock configuration.

The list :
Fresh Roast - good fresh coffee stock, modified excellent small sample roaster
HWP - better fresh coffee, sometimes
Zach & Dani - some of the most delicious coffee, but only with some beans
Bravi - baker of flat dull coffee, all beans
iRoar[s] - surely you're joking
HotTop - decent even drum roast, but a bit flat stock

[Bertie Doe]

Not sure if there is any mileage in adding beans mid roast to a HotTop. Never tried it, but roasts done by inserting beans at high temperatures have been less than exciting. There's also the issue of letting out a good deal of hot air. This will tend to cool the beans as will contact with the cold newly inserted beans. Might be Nirvana...

A HotTop that get's dumped for the new 'programmable' model maybe in his future.

Maybe adding beans during the roast isn't a good idea. Common sense, suggests sticking with single origins for the first six months with a new machine is best. If my Precision can last a few more months, there should be feedback on the new HTop, although the price gap is already large, against the Gene. Thanks guys for all the info and links - I need to do a lot more reading over the holiday period.

[cannonfodder]

I have used the air popcorn popper, made my own drum roaster and have a HotTop. I have always thought the popper brought out the acidity more than a drum. It may just be a misperception on my part, but that is what I think I taste. The popper batch size was too small and when the temperature dips to sub 40F the roast time gets too long and you end up with baked beans not roasted beans.

I built a drum roaster that would do a pound and a half, but I rarely would go over a half pound. I used a rotisserie oven, build a stainless drum, insulated the works and added another 1000 or so watt heating element. once finished I could top off the thermometer at 600F. It allowed me to control my heat. I could draw out my first to second crack times to allow for a proper mallard reaction and carmelized sugars. It was far from a set and forget machine but made a darn good roast.


A year ago I decided to give the HotTop digital a try. Nice machine, very easy (my 7 year old can roast with it) and the batch size is just right for a house with a single coffee drinker. Easy to use and it makes a nice cup. I do miss the ability to temperature profile a roast. You have no heat adjustment on a HotTop (without modifying it). While you can do things like take the bean charge panel off the top to vent some hot air to help prolong roast times, it is a kludge way of doing it. I like my HotTop but wish I had a simple temperature control. It tends to transition from first to second crack in a minute or two depend on the bean. I like to draw the end of first to start of second out to three minutes personally.

[rasqual]

I know that questions on taste are the trickiest ones to answer, but I would appreciate info from anyone who has gone from fluid to radiant and (in general terms) has found improvement or otherwise, in their favs. Thanks

Coming late to the thread, but you might wish to read some of my crazier experiments. I intend to revisit this in a most serious way, but my machinist and I are busy putting together the first production run of a roaster I used at a farmer's market last year. The production model will be a bit Diedrich-like, with a prospect of 60% bean exposure to IR source.

I don't devote a lot of attention to it, but the Salamander IR emitter I ended my IR experiments using is really a remarkable unit. I mounted it to my popper, interestingly enough. If you want to cobble together something for IR, you have a lot to choose from.