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relation between degree of roast and volume increase
freewillow
[img][/img]I have seen numerous data on weight loss as a way to "estimate" the degree of roasting. However everybody knows that weight loss is a function, not only of the degree of roasting, but also the function of the density and especially the water content of the green beans beeing roasted.

I have roasted some beans at sam[img][/img]e degree of roasting estimated by weight loss and change of color. However, using different temperature profile I have coffees that taste differently. The best coffee always had a bigger increase in volume, as crudely measured in a graduated cylinder.

Funny enough, I have never seen a paper covering this subject.

Has anybody outhere some experience and knowledge on the subject? thanks.

P.S. I have tryed to add the graph. Hope it went through but I doubd it.smiley-hot.gif: Ples help

In attachement; grapf of different raost ( different coffee beans)
In red: Volume increase, in Blue: Weight Loss. X axes: 1 is City, 2 City+, 3 FC, 4 FC+ and 5 Vienna.
Y Axes is percentages.
John Despres
I tracked weight with regards to the degree of roast for well over a year and found no correlation. This was during a period where I was roasting upwards of 15-20 batches a week.

Starting and finish weight would indicate the amount of moisture in the bean. But they are only relative to each other in that same bean, not the moisture in the next bean.

You're better off with temperature and sound as your indicator.

John
Respect the bean.
John Despres
Fresh Roast 8, Gene Cafe, JYTT 1k, Quest M3, Mazzer Mini, Technivorm, various size presses and many more brewers.
freewillow
We are in agreement on this John. I think that volume increase is a better indicator, but again, valuable for the same kind of beans.
erik82
Here in the Netherlands most people use a much softer profile on the Gene. Most people never go beyond 455F for SHB and 446F for low grown. Most people here ramp it up to the max and then dial back the heat when 1C begins but still higher than the max of the average profile used here.

I tried both profiles and the softer profile adds around 1,5 min to the total time of roasting. The roasted beans are less puffed up with this profile than with the max ramp. When doing tests I concluded for myslef that I liked the taste of the more puffed beans over the less puffed beans.

Also multiple times roasted two batches of the same beans with one batch Full City+ and the other one City+ but didn't notice a real difference in percentage of weight loss. Tracking my previous 150 roast also didn't indicate a correlation between weight loss and degree of roasting.

So I agree with your finding that bean size is a better indicator than weight loss.
Olympia Cremina 2013, HG one 83mm #0083, Gene Cafe.
Also Zassenhaus grinder, Chemex, Abid Clever Dripper, Kalita Wave, Aeropress, Hario Buono, Bodum Cafetiere and Bialetti Mokapot
ginny
your talking apples and oranges here...

I think freewillow you should forget about numbers and roast by smell, sight and sound for awhile.

people get so caught up in probes measuring devices they ruin their otherwise could be great roasts.

forget what anyone says and simply use your own gut feelings and give it a go.

my first roaster was an original fresh roast, no probes, no nothing.

did not take me long to figure out how tipping and shaking that tiny little thing tossed those beans around and make a more even roast...

ginny

burger sounds good right now...
freewillow

Quote

ginny wrote:

your talking apples and oranges here...

I think freewillow you should forget about numbers and roast by smell, sight and sound for awhile.

people get so caught up in probes measuring devices they ruin their otherwise could be great roasts.

forget what anyone says and simply use your own gut feelings and give it a go.

my first roaster was an original fresh roast, no probes, no nothing.

did not take me long to figure out how tipping and shaking that tiny little thing tossed those beans around and make a more even roast...

ginny

burger sounds good right now...


I understand what you are saying but I do not fully agree. Of course my Ph D background in chemistry puts a heavy bias on what I do. Many peole act like that in cooking too: by feel and guesses. They achieve sometimes great results, but are often at pain in order to reproduce it because feelings and guesswork is very variable. I prefer to measure and think ahead. That does not mean that I do not use, smell, smoke and taste in my portfolio. When it comes to smoke by the way, I generate very little. My gene small shaft collector is still clean after 90 roasts. That I very different from a lot of users of this forum.

It is just that: comparing two Yirgacheffe roasts. One done with a low temperature in 20 minutes and another @ higher temperature of 15 minutes that it occured to me that the first roast ( recommended by kowlegeable people in France) was too acidic. The color and the weight loss were identical. Only the volume increase was very different. This was the reason for my questions.
freewillow

Quote

erik82 wrote:

Here in the Netherlands most people use a much softer profile on the Gene. Most people never go beyond 455F for SHB and 446F for low grown. Most people here ramp it up to the max and then dial back the heat when 1C begins but still higher than the max of the average profile used here.

I tried both profiles and the softer profile adds around 1,5 min to the total time of roasting. The roasted beans are less puffed up with this profile than with the max ramp. When doing tests I concluded for myslef that I liked the taste of the more puffed beans over the less puffed beans.

Also multiple times roasted two batches of the same beans with one batch Full City+ and the other one City+ but didn't notice a real difference in percentage of weight loss. Tracking my previous 150 roast also didn't indicate a correlation between weight loss and degree of roasting.

So I agree with your finding that bean size is a better indicator than weight loss.


Thanks for the comment. Good to hear from a fellow european. If you have some profiles to share, please send me a MP with your email.
ginny
I clearly misread your question.

Quote

It is just that: comparing two Yirgacheffe roasts. One done with a low temperature in 20 minutes and another @ higher temperature of 15 minutes that it occured to me that the first roast ( recommended by kowlegeable people in France) was too acidic. The color and the weight loss were identical. Only the volume increase was very different. This was the reason for my questions.


My MFA limits me to Artisan Roasted Coffee not the tube baby stuff...

thanks for clearing that up.

ginny
Edited by ginny on 12/04/2012 3:09 PM
erik82

Quote

freewillow wrote:

Quote

erik82 wrote:

Here in the Netherlands most people use a much softer profile on the Gene. Most people never go beyond 455F for SHB and 446F for low grown. Most people here ramp it up to the max and then dial back the heat when 1C begins but still higher than the max of the average profile used here.

I tried both profiles and the softer profile adds around 1,5 min to the total time of roasting. The roasted beans are less puffed up with this profile than with the max ramp. When doing tests I concluded for myslef that I liked the taste of the more puffed beans over the less puffed beans.

Also multiple times roasted two batches of the same beans with one batch Full City+ and the other one City+ but didn't notice a real difference in percentage of weight loss. Tracking my previous 150 roast also didn't indicate a correlation between weight loss and degree of roasting.

So I agree with your finding that bean size is a better indicator than weight loss.


Thanks for the comment. Good to hear from a fellow european. If you have some profiles to share, please send me a MP with your email.


PM sent.
Olympia Cremina 2013, HG one 83mm #0083, Gene Cafe.
Also Zassenhaus grinder, Chemex, Abid Clever Dripper, Kalita Wave, Aeropress, Hario Buono, Bodum Cafetiere and Bialetti Mokapot
oldgearhead
I think if you are dealing with water-processed beans that, like most,
were dried from 53% to 12% before shipping, and arrived at your door at 12-13% moisture content then:
.
"There is a relationship between visual color of the roast bean and the percentage of roast loss. A light to medium cinnamon-colored roast which is just within palatable range would have about a 12 per cent loss; a fully developed roast of deep brown but not blackish-dark would have about a 14 per cent loss; a high roast which is dark brown with tinges of black would have a 16 per cent loss, and is the darkest usually used in the United States. However, specialty roasts, such as the French, are very dark brown with some oil slicks on the bean surface, and have about an 18 per cent loss; the Italian roast is black, burnt, and oily at about a 20 per cent loss. In all cases, it is assumed that the green coffee contains about 10 to 11 per cent free water moisture; first deducting 10 per cent water from each roast loss figure gives the pyrolysis weight loss." - Michael Sivetz CE 1963.
oldgearhead attached the following image:
dsc_0095_1.jpg

No oil on my beans...
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