Fluid bed Vs Drum

[garglebutt]

Re: Fluid bed Vs Drum

Given that all the most popular roasters are drum roasters rather than fluid bed I assume that there are a number of reasons for the preference. The typically shorter roast times for fluid beds have been described as somewhat reducing the complexity of the coffee even though it is also described as brighter. Comparing the results of fluid bed to drum roasting where the beans are not taken to the same roast level is like comparing red and green applies.

Drum roasters offer control of every aspect of the roast whereas the air flow in a fluid bed is usually not controllable without custom mods such as Mals. If fluid bed roasters offered programmable air flow during a roast they would be more in line with the flexibility of drum roasting.

I think the main gist of this thread was in relation to home roasting and for this you have a choice between: modified popcorn poppers and dedicated coffee "popper" designs like the iRoast, and some variation of a drum roaster starting from a heat gun in a dog bowl up to a HOTTOP or BBQ drum.

Since beans outgass during roasting the beans are not going to take up much flavour from a seasoned drum so I dont agree with Javaphile on that point. The simple answer is that if you want to roast more than about 100-150gm at a time you will end up being a drum roaster.

[Javaphile]

Re: Fluid bed Vs Drum

Given that all the most popular roasters are drum roasters rather than fluid bed I assume that there are a number of reasons for the preference.

Drum roasters are the most popular? Amoung what demographic? Amoung home roasters fluid bed roasters far outsell drum roasters. In the commercial roasting community drum roasters are used almost exclusively over fluid bed roasters simply because of their efficiency. Fluid air bed roasters (at least as they are currently designed) are economical only on a small scale.

The typically shorter roast times for fluid beds have been described as somewhat reducing the complexity of the coffee even though it is also described as brighter.

I cant speak for other roasters as Ive no personal experience with them but with my Z&D roaster I had no problem achieving the ideal roast time of 15-17 minutes simply by adjusting the amount of beans roasted.

Comparing the results of fluid bed to drum roasting where the beans are not taken to the same roast level is like comparing red and green applies.

Agreed, when dealing with the flavors native to that bean, but not when dealing with flavors that have been introduced from an outside source.

Drum roasters offer control of every aspect of the roast whereas the air flow in a fluid bed is usually not controllable without custom mods such as Mals. If fluid bed roasters offered programmable air flow during a roast they would be more in line with the flexibility of drum roasting.

I think the reason fluid bed roasters dont offer such a control is a matter of economics and idiot proofing. The fluid bed roasters are aimed at the entry level roaster and are priced and designed accordingly. Adding a variable fan control adds costs to its production and makes the roasting process no longer the set and forget experience that is in such high demand by the average consumer.

Since beans outgass during roasting the beans are not going to take up much flavour from a seasoned drum so I dont agree with Javaphile on that point.

As a drum roaster rumbles around with the beans rolling around inside it they are leaving behind their oils on the drum as well as plenty of smoke residue. Both of these of course having tastes and smells distinctive to the bean being roasted. When that roast finishes and the next batch of beans is put in there is plenty of these residues left behind. The new batch of beans are in physical contact with these residues as they tumble around in the drum. The residues flavors dont have to be absorbed via a gas exchange as they are being transmitted to the beans via direct contact. Look at what youre roasting your beans in. When you finish a roast theres smoke stains and, if you take the roast far enough, oils on the surface of your drum/bowl/collander/whatever. Unless youre using a drum odds are you wash your roasting container when youre done. Drum roasters dont get washed, those oils and smoke residues remain, ready to taint the following roast. And they can indeed flavor the following roast.

As my tastebuds became more educated to the different coffees and their flavors I found that in quite a few of the coffees I was buying from my local speciality roaster I could identify the bean that had been roasted before the batch I was drinking had been.

With us home roasters this is not as big an issue because we generally dont roast as dark as commercial roasters and so dont produce anywhere near as many oils nor smoke. While well pull a roast when it has at most a few specks of oil showing the majority of roasts I see coming out of the commercial shops are completely covered in oil.

As Im sure others here who sell such items will attest drum roasters need to be seasoned with a few roasts when first purchased and in fact every producer of drum roasters Im aware of tells you so in the owners manual.

The simple answer is that if you want to roast more than about 100-150gm at a time you will end up being a drum roaster.

This seems to be because of economics, not because the drum roasting process is neccessarily better than the fluid bed method.

Whew! That was several mouthfuls!

Now, with all that said I think the only people who would be really concerned with it all are the Single Origin roasters/drinkers. If youre doing blends the seasoning is a good thing. It adds depth and a broader range of flavors to the roast, exactly what you want in a blend. However, if youre doing SOs and want to taste purely that bean then those left-over flavors from the previous roast become an unwanted contaminant. :P

And so once again, we have a very subjective issue. It all depends on what youre looking for in your roast. There is no right or wrong answer, theres only the answer that works best for your tastes and pocketbook. As well as other highly subjective things like the willingness of ones other half to put up with ones obsession and tearing into appliances for that perfect part for your new roaster mod. ;D ;D ;D

Java "Off to put his fingers on ice to cool them off" phile

[poundy]

Re: Fluid bed Vs Drum

http://www.sivetzcoffee.com/

Commercial size fluid bed roasting.

[papalui]

Re: Fluid bed Vs Drum

Interesting link Poundy. The 1.25 pound roaster looks interesting. I wonder what it costs?

[Fresh_Coffee]

Re: Fluid bed Vs Drum

This has been a very interesting discussion particularly as it shows quite a deep interest and much articulation from home roasters, and as Java has said the topic is quite subjective. However, just a couple of points:

A) Java, re your description of what commercial roasters in the US do....this is not intended to be misinterpreted, it is just a simple fact that many are generally into burning good coffee by basically over-roasting. In terms of simplifying this style for the readership, this is basically the southern italian style of espresso roast...turn it black and let it "bleed" (oil). Over here we tend to follow the northern Italian espresso kind of roast which is not to roast much darker than a cinnamon coloured roast. This is mentioned simply so you will know that commercial roasting drums over here, are not as well "seasoned" with oily charcoal as you might think!

B) re: "....As my tastebuds became more educated to the different coffees and their flavors I found that in quite a few of the coffees I was buying from my local speciality roaster I could identify the bean that had been roasted before the batch I was drinking had been....." Hmmm. Really?

C) A recognized world authority on a lotathings coffee, our own Australian coffee expert Ian Bersten, designed and built several "shop" sized bench roasters of the fluid bed type, and he also designed and built (from memory so could be not quite correct but shouldnt be far wrong  ;D)   a 30 & possibly a 60 kilo fuid bed roaster atleast one of which (from memory) went into commercial roasting in Sydney. This was done at the same time as German manufacturer Neotech was doing much the same thing only going even bigger. Sivetz might have been working on the same things at the same time, or maybe later, cant remember.

It would be interesting for Ian to give us the benefit of some practical knowledge on the subject for purely academic reasons. He is very "scientific" and if he is able to give a comparison (between fluid bed and drum roasting), you should be able to bet your bottom dollar that it has been well researched and is..."no bull". Andy?

Cheers,
FC.

[Javaphile]

Re: Fluid bed Vs Drum

Yeah that is an interesting link, too bad they dont post prices. :-/

Note the gas consumption on the larger ones, 5-6 times what drum roasters of the same size use. Even with being able to roast twice as much every hour as a drum thats still 2.5-3 times higher gas consumption. Their afterburners also consume more gas as the air is being moved through at a much faster rate.

Java "Hhhmmm...Technology!" phile

[Javaphile]

Re: Fluid bed Vs Drum

FC,

Its really good to hear yall arent destroying the coffee the way the roasters around here do!! :P :P :P

Yes I really could taste the previously roasted beans in some of the batches. One case that really stands out in my memory that happened early on in my journey down the home roasting obsession path was when I bought some pre-roasted Peruvian to taste test against some home roast as Id heard that it was one of the varieties that didnt roast well in a fluid bed. I also chose it because it was one of their lightest roasts with the beans showing just a speckling of oil 4 hours after being roasted. When I sat down the next day and did the taste comparison there was a HUGE difference in tastes with the commercial beans exhibiting flavors that were no where to be found in my fluid bed batches. It really threw me for a loop initially. I had expected a difference but not *this much! The whole time I was trying to figure out why thered be this huge difference there was this little hair on the back of my neck niggling at me and it finally hit me. I *knew one of those flavors that was only in the commercial batch, and it wasnt a flavor Id ever tasted in any bean from Peru. In fact it came from a different continent. I was tasting Kenya AA in my Peru! Once I identified that particular taste I then tried to place the other 2 flavors that were only in the commercial roast. One was faint enough that I really couldnt even take a guess as to its origins. The other one I cant say for certain what variety it was but Id be willing to bet it was from a bean similiar to a Sumatra Mandehling. It was just a hint of that earthy flavor. I ended up going out on a service call that afternoon close to the roaster so I stopped in and asked him what hed roasted just before the Peru. It was Kenya AA. This experience settled for me once and for all the question of whether seasoning effects a change in the flavor of the beans being roasted. While I could be wrong on my assessment of the the earthy flavor as having come from a Sumatra Mandehling or similiar type bean there was *no doubt about the Kenya AA flavor. Once Id put the name to it it was one of those *duh* How could I *not recognize that flavor? moments. It was that obvious.

Id love to hear Ians thoughts on this! Itd be great to hear from someone with such firsthand knowledge of the subject!

On the seasoning issue I would think that commercial sized fluid bed roasters would season the same way a drum would as the roasting chamber on them would not be cleaned all the time as they are on the smaller scale fluid bed models. Perhaps it wouldnt season as fast nor as heavily as the beans are in contact with the walls less as theyre floating? Hhhmmm....something else to think about, like I needed anything more! ;D

Java "Putting a bag of ice on his head to cool it down from the thinking overload" phile

[Framey]

Re: Fluid bed Vs Drum

Java

Your ability to taste beans from a previous roast is freaking me out!

Try it a few times and see how you go, and if you are consistently right, perhaps you should take a crack at some sensory judging.


Stephen

[garglebutt]

Re: Fluid bed Vs Drum

As my tastebuds became more educated to the different coffees and their flavors I found that in quite a few of the coffees I was buying from my local speciality roaster I could identify the bean that had been roasted before the batch I was drinking had been.

And you do that in 1:3 milk based drink. I think you need to give Kenneth Davids a call.

Drum roasters are the most popular? Amoung what demographic? Amoung home roasters fluid bed roasters far outsell drum roasters. In the commercial roasting community drum roasters are used almost exclusively over fluid bed roasters simply because of their efficiency. Fluid air bed roasters (at least as they are currently designed) are economical only on a small scale.

I was talking about the whole market but even in the home market a majority of the discussion Ive seen has been about dog bowls and BBQs. Popper roasters outsell drum based roasters because there are only a few home drum roasters on the market and they are more expensive. Everyone else is DIY.

[Javaphile]

Re: Fluid bed Vs Drum

Hey Stephen,

People have told me for decades I should get involved in some sort of taste or smell testing. Most people refuse to believe the ability until something happens to prove it. Sometimes Im amazed myself as Im a pretty heavy smoker but I consistantly run into situations where I smell or taste something that others around me cant. Usually this drives me nuts until I can positively identify the source of the smell or taste just to prove to myself that Im not imagining it.

The down side of this is there are some foods I simply cant eat if I want to taste anything else. Cilantro is the worst offender. One tiny piece of it and its like someone set off an atomic bomb of cilantro in my mouth wiping out all other tastes for hours afterwards. Depending on the freshness of the cilantro it can take more than 24 hours before my tasting ability returns to normal. Needless to say I avoid anything with cilantro in it like the plague.

One of the smells that really jumps out at me is the smell of hot anti-freeze in cars. If a car has even the tiniest coolant leak I can smell it from many feet away. If I spill any anti-freeze when filling the radiator on my car even wiping it all up Ill be smelling it for weeks afterwards as the tiny residue left behind gradually burns off.

Last year when I was camping with some friends there was a smell occassionally wafting through the campgrounds that I thought smelled *wonderful! I initially thought it was someones perfume and I commented on it several times over the course of the week-end and everybody just looked at me like I was nuts as they werent smelling anything. Finally after 2 days of being told I was imagining things I decided to track the smell down. It took me about 20 minutes to finally trace the smell to a tree that was about 150 meters into the woods from the campsite. I cut a small branch off and carried it back to the campsite where I proudly displayed it saying I *knew I wasnt crazy! This is the smell Ive been talking about all week-end! Of the dozen or so people there nobody could smell it until the branch was literally inches away from their noses, and even then there were 2 people who said they didnt smell it. LOL I took the branch around to several arboretums to try and identify it as I wanted to plant some of the trees on my property as I *really liked the perfumey smell of them. Unfortunately it turns out its classified as an invasive species/noxious weed and the state is on a major campaign to wipe it out and its illegal to sell or even transport it with-in the state. So much for filling my house with its perfume.

As far as tasting the previous roast the testing I did of this was very limited as the roasted beans were expensive as h*ll and roasted *way to dark for my tastes. In probably 75% of the roasts there were hints of flavors from previous roasts but they werent distinctive enough to say with certainty that they were from a previous roast. Only in maybe 15-20% of the beans could I identify with certainty the presence of a flavor from a previous roast and in all cases it was with a bean that was mildly flavored where a bean with a strong distinctive flavor had been roasted before it.

Because of this when I roast I always roast up the milder flavored bean first with the stronger flavored coffee being done afterwards. If the two varieties Im roasting (I always roast up at least 2 different coffees when I have a roasting session) are similiar in their strength of flavors I do a complete cleaning of my roaster before switching to the new bean.

Ive been attempting to get in on some cuppings with the local roasters and importers but so far only one has expressed an openess to allowing me to attend a cupping of the beans theyre testing. Ive never done an actual cupping so Im looking forward to the experience.

Java "*sniff sniff* What *is that smell? Oh sorry! Ill put my shoes back on!" phile

[clarexican]

Re: Fluid bed Vs Drum

Hi JAVAPHILE

have you read this book Perfume by p. suskind?
http://www.amazon.com/exec/obidos/tg...64950?v=glance
there is a link to it at amazon.
What you just said reminded me of this book, except for the evl part :P

if you havent read it it is brilliant! and you just HAVE TO.

clarexican

[Javaphile]

Re: Fluid bed Vs Drum

I was talking about the whole market but even in the home market a majority of the discussion Ive seen has been about dog bowls and BBQs. Popper roasters outsell drum based roasters because there are only a few home drum roasters on the market and they are more expensive. Everyone else is DIY.

I think this is most likely because the type of people who buy a pre-made home fluid bed roaster arent the type who are coffee snobs and participate in discussions of this nature. Theyre the type who enjoy their coffee but want a push and forget type roaster that doesnt cost them an arm and a leg.

The DIYers on the other hand are people who are much more hands-on and are generally more interested in producing the best coffee possible, who dont mind futzing with their set-up, and who quickly out grow the small batch and control limitations of inexpensive DIY fluid bed roasters. A DIY drum roaster with a half kilo or more capacity is much cheaper and easier to build than a fluid bed roaster with similiar control capabilities and batch size capacity. Once again its a matter of economics and ability (how many of us are sparkys?), not the inability of fluid beds to produce good roasts, that leads DIYers down the drum path.

Java "DIYer at Large" phile

[Javaphile]

Re: Fluid bed Vs Drum

Hey Clarexican, that looks like a good book. Ill have to hunt up a copy. Reading the blurb on that link flashed me back to the late 70s when I was traveling the world and the horrendous smells I encountered in cities.

Venice was bad enough with the open cesspools of its canals but it paled in comparison to the smell of places Like Port au Prince or Rio, or Manila. Uffda they STANK! :-X

Java "Holding his nose at the mere thought of those places" phile

[clarexican]

Re: Fluid bed Vs Drum

hey Java

Yay! let me know what you think of the book, I think it is brilliant i Love the imagery on the first page ....

clarexican

[Javaphile]

Re: Fluid bed Vs Drum

Woohoo! My local library has a copy. Ill have to swing by there tomorrow when Im out and about. 8)

Java "Woohoo! A new book to read!" phile