International experts and coffee aficionados all agree that air roasted coffee causes less harm to the bean during the roasting process and the resulting roasted bean is less bitter and more evenly roasted.
I've got to totally agree with this. Not only is it a more even roast, but I also know that much less smoke is circulated around the roasting beans. This way darker roasts can be achieved without a real charcoal or overly smokey taste. The cooling process is also much different in the air-roasters.
As a drum roaster I have to disagree. Although as you say,
"International experts and coffee aficionados all agree that air roasted coffee causes less harm to the bean during the roasting process and the resulting roasted bean is less bitter and more evenly roasted."
I'd like to ask you what came first, drum roasting or hot air roasting? Although you say that the beans are more evenly roasted, which tastes better? In my opinion, drum roasted beans tastes much better. In addition true roasters know how to adjust the flame along with air mixture to produce consistent roasts. We also have the freedom to create whatever profiles we want for our customers. I have yet to have a customer that preferred an air roast over a drum roast.
Last time I posted info on this subject my inbox was flooded with nasty e-mails so please, this is my opinion only...
In regards to evenness of the roast, it is true that an air roaster produces a more even colour. This is only with one type of bean, I've found that drums tend to have more even roasts when it comes to roasting blends.
Also, and this is not fact, I find that drum roasters produce better body. Both types will highlite different characteristics of the flavour, and it comes down to personal preferance in the end.
Although, altering roast times will vary flavour, air roasters roast faster - this is the argument behind the body of the coffee discussion.
From a strictly scientific view, drum roasters typically take longer to roast the same amount of coffee as an air roaster. So the chemical process of pyrolysis can work longer, causing (in my opinion) fuller development of the flavor compounds in the coffee. This is part of what nzroaster is referring to.
Also, and this is not fact, I find that drum roasters produce better body.
Drum roasters also have better controls in virtually every aspect; temperature control, air flow, and time. A roaster who knows how to control these variables will produce a superior cup every time. (Again, in my opinion.)
It's all about applying temperatures to the product.
Drum Roasters use secondary heat Air Roasters use primary heat.
DRUM: heat source heats drum, drum heats air, air heats beans
AIR: heat source heats air, air heats beans.
Heat transfer rates in air roasters are probably twice as efficient as in drum roasters.
Roasting process in a Air Roaster is faster, about half the time.
That gives you the time to exactly design your taste profile.
In a drum roaster you do not have that time, normal roasts take 12 minutes how long do you want to roast coffee 24 minutes? That is not going to do any good for the aromas. Of course you can buy computer controlled Drum roasters, go get a quote. There is only so much a simple drum roaster can do. The contact the bean has with the secondary heat source causes heat spots, you will never have that in an Air roaster.
How do we roasters check the quality of a roast: we break the bean and look if we have one even color from surface to surface. But look at the hotspots, having hot spots you already have two degrees of roast in one batch. How are you going to control that? You cant.
Even you look at the top end equipment in big setups today it is a combination of drum and air, and believe me if they could do without the drum they would.
However it is impossible to move 120 KG of beans with air alone. So the Drum in newer developments has the task to move the beans, that’s it.
Primary heat, drum movement. Still, the temperature control is not perfect.
The Roast is the foremost component that determines the taste of the end product.
The most important stage for aroma development is the medium stage, and with an Air Roaster you are in control of airflow and temperature.
Meaning: the bean temperature can be stabilized because of the vast throughput of air. In a Drum roaster the beans after some roasting have become a heat source it self. It is difficult to stay at the same temperature for a while to accommodate better aroma development.
This clearly puts Air Roasters ahead of Drum roasters.
Drum Roasting is more romantic, Yes and it is definitely something for romantics.
Computers have taken over control and that will also be the future in coffee roasting. Profile roasting is the future too and total control over process will be the aim of development. Drum Roasting will not be the future, in fact it has been the past for quit a while.
I also would like to add that it is taste at the end of the day and who likes smoked coffee likes it, probably because he never had a clean product.
Its time to move on, no offence.
I think the biggest Air Roasters can take 2 – 4 pounds per batch, however they roast espresso in 7 minutes spending some extra time in that medium stage of bean dehydration (between 7-2%), which is the stage where most of the aroma compounds are developed.
do you own a popcorn...sorry air coffee roasting company? Air roasting is the future eh? Haha your telling me a company could stay in biz while only producing 34 lbs per hour...lets see...if I was to roast on an air roaster I would have to roast 90 hours to produce the coffee I need today. :roll: Maxtor you said "Its time to move on, no offence" Non taken and I am not really to worried about my future as a drum coffee roaster. :wink:
Thanks for the reply,
The only point you are making is that the capacity of an Air Roaster for your business would not be enough; I mentioned 120kg per batch, Air roaster.
Roasting times 3.5 to 10 minutes.
I believe that this would suffice donâ€™t you think?
But than Christopher likes to roast in small batches â€œSmaller batch size allows our roasters precise control of temperature and humidity during the entire roasting process. This careful attention to detail ensures superior quality.â€
I have played with the little "home" hot air roasters...wasn't too impressed...you put the coffee in turn a dial and it turns the coffee brown...no airflow adjustment...no heat adjustment it is all or nothing..true I have never used a "commercial" air roaster...if you can consider the small amounts to be considered commercial..as to small batches I do 1 pound sample batches in my 2 kilo roaster...but you are welcome to your opinion...I never said that air roasting was crap as to you say drum roasting is...all I said was in my "opinion" I like drum roasted coffee over air roasted. Too each their own...I guess it comes down to what makes your customers happy. How much coffee are you putting out? How long have you had your your cbx? I own a '69 cb350 ?
Okay, my turn to chime in...Air roasting vs drum roasting...Yes I agree drum roasting is very romantic, as a matter of fact it is an art form. Some of us that have chosen drum roasting over air roasting are from old school and have learned the true art of roasting. Although I appreciate the 101 on air roasting, the thought that this is the way of the future baffles me :roll: . I'm sure it's nice to pop a switch and walk away for awhile then come back and walla your roast is done, but I still believe in old school methods. I've gone up against some air roasters here, and customers have chosen the drum roast over the air roast everytime. I'm sure you believe in your air roaster theory about cleaner roasts and all of that, and that's great, but understand there is a certain taste that a drum roaster produces that an air roaster can not. Now we can get all scientific and technical but the bottom line is not to knock one another's roasting ability, but rather see what the customer enjoys more.
If you want to be coldly scientific about it Maxtor, air roasters don't provide a long enough roast profile to allow for the full effect of pyrolisis to occur. Your aroma cannot fully develop. The "clean" taste that you seem to be so fond of is simply the lack of full flavor development that is the result of air roasting.
You are also misinformed about the "primary" heat source of the beans. Every drum roaster I've used (the oldest was built in 1923) has used convection air as the primary heat source. The drum is also heated, but hotspots do not occur if you have any idea of how to control your roast. If you feel that a computer can do a better job than you can, please use a computer. I will never believe that a computer can do the same job that I can. Simply put, computers do not have intuition, they do not have the ability to sense the the minute changes that can occur in what is a natural product and adjust for them. An air roaster is an engineers answer to mass production, without regard to the end result. The "popcorn popper" that Topher refers to is the original device that Carl Sivitz used when developing the fluid air bed roaster. It was quite literally an air popcorn popper, which he modified.
As far as the "big boys" are concerned, you don't seem to be aware of the truly large roasting systems which use a conveyor belt system to move the coffee-no drum is involved. Anybody who really just wants to roast the most coffee in the most time uses one of these. Oh, and by the way-the man who developed these marvels of modern technology was...Carl Sivitz. :!:
I am not talking about home roasters I am talking about serious Air Roasters. They have a 2-pound batch and an output of 16 to 20 pounds per hour.
I am also not saying that drum roasting is crap; I was brought up on drum roasting. I started roasting coffee when I was 15, about 25 years ago, and as you can imagine it was a drum roaster. I only work with Air Roasters for the last 3 years.
Max output on my roaster is 160 pounds per day. The cooling cycle for 2 punds to 35 degrees is 2 minutes.
The good thing is you could roast 24 hours no cooling of the machine needed.
I ride my CBX since 1996, bought it in Rochester with original 7500 miles on it. Itâ€™s my everyday bike, love it.
I havenâ€™t seen a 69 cb 350 in years, you got to keep it itâ€™s a great bike to have.
Your bottom line is that customers enjoy your coffee more than the one from the Air Roaster that might simply be because you are a better roaster than the Air Roaster guy. I am not knocking on others roasting ability, I am sure you could do a great job on an Air roaster as you seem to be experienced.
See there are two things when it comes to coffee.
One is personal taste, not discussable in my opinion.
Second are technique, method, and most important control over process.
What I am saying is future developments will focus on â€œcontrol over processâ€
The rather lengthy article you quote really seems to be aimed at the larger, more industrial style roasters. My guess is they are going to be extremely expensive, if and when they become available at all. Don't get me wrong, I'm all for improvement of the process, and effiecency, as well. If someone can come up with a better way to produce the same quality product, I'm all for it.
Regarding the pyrolitic process, I wasn't as complete in my original statement as I should have been. It's not only time, it's the temperature applied during the process. If you want a full explanation I refer you to any number of books available on the subject of roasting. In my experience, it takes a mimimum of 12 minutes at a drop temeperature over 400 degrees farenheit. This has to be adjusted for type of bean and size of roast, as well as the style of roast.
You are right in that it is a matter of taste, but I will put air roasted coffee up against drum roasted coffee and be able to tell which is which every time, because the air roasted coffee does not have the full flavor that the drum roasted coffee has. There are some interesting developments being made in thermal conservation and recycling of heated air with drum roasters.
What it comes down to is this; we have different approaches. You believe that you can rely on a machine to reproduce the profile you have created. I believe that there are factors that change with every roast, even if it is the same coffee and the same size roast. No machine can be programmed to adjust for them. It appears that you believe you are producing a product like a car, or a stereo, and are doing so in an assembly-line manner. I am producing food that is the equal of any fine wine, that is the best of what can be done with the best product I can find. My original training is as a chef, and I approach coffee with the same passion and dedication that the great chefs apply to their food. What I do cannot be reduced to numbers in a machine, or any formula of a+x=y. That is why you and I will never agree on this subject, and that's ok. You are a scientist-I am not.