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how to roast very fresh green beans?
relacker
i received a pack of sidamo, it looks almost undried. so when i apply my usual roasting profile of 185degC 5min. 235degC 5.5min then 242degC til EOR, it gve me a sour taste.

the supplier told me the sidamo itself is a bit sour and cos its very fresh. so to reduce sourness, start off with higher temp.

i found profile in this forum for sidamo that starts with 223degC.

can anybody advise?
 
Koffee Kosmo
You can dry them in the sun for a week or so
Also try for first crack at a time of 9 to 11 minutes followed with a 4 to 6 minutes to second crack

KK
I home roast and I like it. Designer of the KKTO
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seedlings
I thought there were standards for green coffee moisture content and trade (just like corn must have a certain moisture content to be sold), and think it might be unusual to have more than a few percent difference from bean to bean.

So, if it really does have too much moisture then start the roast slower at a lower temperature for a minute or two, then go to your normal profile temperatures.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
Unta
Industry standard is 9-13 %
"The SCAA and ICO standard for green coffee moisture is 9% to 13%.

The reference method is to bake a sample at 105C/220F in a convection oven for 24 hours and note the weight loss, 1 - (weight after)/(weight before). If you bake exactly 100 grams, then the percentage is 100 - after.bake.weight. This is called the ISO6673 or Karl Fisher method.."
Seems like quite a challenge to keep the oven @ 220 degrees over 24 hours accuratly.
Heres the HB link where the info came from.
http://www.home-b...13613.html
Edited by Unta on 09/13/2011 11:51 AM
Sean Harrington
educate.
 
endlesscycles
Willem Boot has suggestions in this article: http://www.bootco...ROAST1.pdf
-Marshall Hance
Asheville, NC
 
oldgearhead

Quote

Unta wrote:
Industry standard is 9-13 %
"The SCAA and ICO standard for green coffee moisture is 9% to 13%.

The reference method is to bake a sample at 105C/220F in a convection oven for 24 hours and note the weight loss, 1 - (weight after)/(weight before). If you bake exactly 100 grams, then the percentage is 100 - after.bake.weight. This is called the ISO6673 or Karl Fisher method.."
Seems like quite a challenge to keep the oven @ 220 degrees over 24 hours accuratly.
Heres the HB link where the info came from.
http://www.home-b...13613.html


This is a very common method of determining % moisture in about anything. It is used in several common water, and waste water tests, as well as the standard used to standardize faster moisture testing instruments.
Several lab-grade ovens are available that have no problem maintaining a set temperature.

The most common stored comodity in the USA is corn. The moisture in corn must be reduced to 8-10% for storage and/or barge transport to the gulf.

I would suggest holding the beans at 230F for 5 minutes, then start your ramp to first crack..
Edited by oldgearhead on 09/13/2011 2:43 PM
No oil on my beans...
 
Ringo
I dry hardwood lumber for my day job, I use this test every day. On wood samples you can use a microwave if you are careful. Set the power level to low or 10%, use a turntable. Run microwave for a min weigh your beans, wait 30 to 45 seconds run the microwave 1 min. Weigh your beans, if the dropped in weight keep going. A wood sample will take 10 min or so. Make sure you leave the time between running the microwave so the beans can cool a little. If you go too fast the insides will char and give you a bad reading. I have never tried this on beans but it should work. When I want to check moisture contents I use my oven at work.

Ringo
All you need in life is ignorance and confidence, and then success is sure. Mark Twain
 
Unta

Quote

Ringo wrote:
I dry hardwood lumber for my day job, I use this test every day. On wood samples you can use a microwave if you are careful. Set the power level to low or 10%, use a turntable. Run microwave for a min weigh your beans, wait 30 to 45 seconds run the microwave 1 min. Weigh your beans, if the dropped in weight keep going. A wood sample will take 10 min or so. Make sure you leave the time between running the microwave so the beans can cool a little. If you go too fast the insides will char and give you a bad reading. I have never tried this on beans but it should work. When I want to check moisture contents I use my oven at work.

Ringo

This seems more up my alley. Is a turntable absolutely necessary?Any suggestions on amount of beans? What size piece of wood do you use?
Thanks Ringo!
Sean
Sean Harrington
educate.
 
Ringo
The samples I do are 1" x 1" x 8" I usually do 8 at a time. We only do this when we need a fast number because there is a higher chance for error. The normal process would be to put these samples into an oven for 20 hours. Then I check 24 hours later. The 8 samples will go into a math formula and control 65,000 board of lumber in a kiln so accuracy is important. Most kiln operators are using computers to control all this I still like the old fashion moisture samples. As for what sample size I would base on the scale you have access to, if you have a scale for your espresso shots use a wet sample it can weigh. I do not think the turn table is a needed. I use a gram scale with .oo accuracy, expensive scale and very touchy you do not need that kind of accuracy.
Ringo
Edited by Ringo on 09/13/2011 7:55 PM
All you need in life is ignorance and confidence, and then success is sure. Mark Twain
 
Unta
To really throw this thread off the beaten path, Why don't you use a probe type meter?
Sean
Sean Harrington
educate.
 
relacker
so question, in general how do u reduce the sour taste in your roasting profile?
 
Ringo
I dry lumber the way they did 150 years ago, I am old and was trained many years ago by a 75 year old man who believed the old way is the best. Lots of kiln operators plug in the probes turn on the computer, I think my lumber is better. Very competitive business now so it has to be good. Sorry for the hyjack. I think what we are thinking is these beans are at a higher moisture content and need a longer drying phase when roasting.
All you need in life is ignorance and confidence, and then success is sure. Mark Twain
 
Bhante

Quote

Ringo wrote:
I dry lumber the way they did ages ago, I am 150 years old and was trained many years ago by a 75 year old man who believed the old way is the best. Lots of kiln operators plug in the probes turn on the computer, I think my lumber is better. Very competitive business now so it has to be good. Sorry for the hyjack. I think what we are thinking is these beans are at a higher moisture content and need a longer drying phase when roasting.
---------------------------------------------------------------------------
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Wow!
Edited by Bhante on 09/14/2011 9:43 AM
 
Bhante

Quote

relacker wrote:
so question, in general how do u reduce the sour taste in your roasting profile?

The important thing is to spend more time below 120 degrees Centigrade (250 Fahrenheit) than you would with other coffee. How you achieve this depends to some extent on the type of roaster you use. The only fluid bed roaster I have ever used gets the beans completely dry in (I think) 2-3 minutes, but a small drum roaster can take a lot longer.

I would recommend trying an extra 5 minutes (less if it is a fluid bed) at low temperatures (i.e. 100 to 120 C) before the beans are exposed to any temperatures above 150 Centigrade.

You could also put the beans in an oven - thinly spread out on a large tray in the centre of the oven, preferably a convection oven - and dry them at 105-110 C for 30 minutes, then put them directly into the roaster.

I would definitely not recommend starting at 223 C if the beans are very moist - the roast will be very acidic and very uneven. They are also likely to be scorched on the outside and under-roasted inside (break the beans in half and look at the cross-section). On the other hand if you have very high density beans from a high altitude you will not get good results with the above method - in this case it is better to dry the beans slowly and thoroughly first, before roasting them. I have very little experience with very high density beans but they need a very different approach and need very high energy from the start.

There is a standard for moisture in coffee beans, but that doesn't mean the beans agree with that standard! If it is within the standard the moisture should be in the range 9-13%, but it is possible to find coffee stored and shipped at 25%! Such coffee will almost generally be badly spoilt. For example if the coffee was harvested and dried at 1000m altitude in the humid season (which is necessary in some places) then it is extremely difficult to dry it adequately, and over-moist coffee will result. Also if you picked the coffee from the trees yourself you will have big rubbery beans with very high moisture content (I'd guess around 70%) - such beans obviously can't just be plonked into the roaster and roasted as normal. If one had a sample of freshly picked beans that one wanted to test roast immediately, the only way would be to dry them in an oven first. If you press into the bean with your fingernail do you get an impression?

The above concerns your original question which refers specifically to the high moisture. More generally of course there are many other factors which can increase or decrease the acidity. First is the type of bean - Sidamo is known as a bean with relatively high crisp acidity. Secondly and also with respect to the roasting profile, the level of roasting drastically affects the acidity in the final beans. Taken soon after first crack the acidity will be very high. By the start of second crack the acidity will be substantially reduced. If taken well into second crack most of the acidity will have been converted into sweetness and body. The proportions of time spent in the different roasting stages have a major effect on these changes. Also of course the grind and method of preparation will further affect the acidity in the cup.

Bhante
 
Bhante

Quote

seedlings wrote:
I thought there were standards for green coffee moisture content and trade (just like corn must have a certain moisture content to be sold), and think it might be unusual to have more than a few percent difference from bean to bean.

Coffee as it is shipped varies very widely in moisture content, and wide differences in moisture content are the norm rather than the exception. The climatic and political (i.e. who processes the coffee, how and where and with what technology) conditions at origin are the major effect. If the coffee is shipped moist from tropical countries it will in general be badly spoilt (fermentation and mould) before the ship arrives at its destination port. That is the most important reason for the standards, but not all coffee meets the standards. I have seen some incredibly spoilt beans, that were eventually sold to Japan for making coca-cola (what a waste - the original quality of the beans was very high, if they had been properly processed)!!

The classic exception to the degradation rule is Monsoon Malabar - in this case a mild fermentation in the ships sometimes actually improved the coffee, and these days the fermentation is generally artificially induced at the point of origin and controlled, following which the beans will be dried so that they will not deteriorate. Java old brown is a related case; the effect is somewhat different, but in both cases the period of moist storage reduces and softens the acidity in the final cup.

Storage at more than 13% will significantly reduce the shelf life of the green beans. Reducing the moisture content too much (to 6-7%) will also permanently damage the beans. The only tool for enforcing moisture levels is in the terms of a contract, not in international standards. Buyer beware!

Moisture content can even vary by 4 or 5 percent in your own home (in either direction) relative to the beans you purchased, as a result of differences in humidity in your home compared where they were previously stored. You may also find that coffee from one specific supplier (regardless of origin) will differ in moisture content by a few percent from that of another supplier (also regardless of origin), according to the storage conditions your supplier uses. This will result in a marked difference in weight loss for the same roast level and similar roast profile.

Bhante
 
Bhante

Quote

Unta wrote:Heres the HB link where the info came from.
http://www.home-b...13613.html

Thanks for the link, in it there is this link:
http://www.ctahr....f/EN-3.pdf which is very interesting. Our TC4 could obviously be adapted to measure moisture by capacitance, which could be interesting.
 
endlesscycles
http://forums.roa...&t=259
-Marshall Hance
Asheville, NC
 
relacker

Quote

Bhante wrote:

Quote

relacker wrote:
so question, in general how do u reduce the sour taste in your roasting profile?

The important thing is to spend more time below 120 degrees Centigrade (250 Fahrenheit) than you would with other coffee. How you achieve this depends to some extent on the type of roaster you use. The only fluid bed roaster I have ever used gets the beans completely dry in (I think) 2-3 minutes, but a small drum roaster can take a lot longer.

I would recommend trying an extra 5 minutes (less if it is a fluid bed) at low temperatures (i.e. 100 to 120 C) before the beans are exposed to any temperatures above 150 Centigrade.

You could also put the beans in an oven - thinly spread out on a large tray in the centre of the oven, preferably a convection oven - and dry them at 105-110 C for 30 minutes, then put them directly into the roaster.

I would definitely not recommend starting at 223 C if the beans are very moist - the roast will be very acidic and very uneven. They are also likely to be scorched on the outside and under-roasted inside (break the beans in half and look at the cross-section). On the other hand if you have very high density beans from a high altitude you will not get good results with the above method - in this case it is better to dry the beans slowly and thoroughly first, before roasting them. I have very little experience with very high density beans but they need a very different approach and need very high energy from the start.

There is a standard for moisture in coffee beans, but that doesn't mean the beans agree with that standard! If it is within the standard the moisture should be in the range 9-13%, but it is possible to find coffee stored and shipped at 25%! Such coffee will almost generally be badly spoilt. For example if the coffee was harvested and dried at 1000m altitude in the humid season (which is necessary in some places) then it is extremely difficult to dry it adequately, and over-moist coffee will result. Also if you picked the coffee from the trees yourself you will have big rubbery beans with very high moisture content (I'd guess around 70%) - such beans obviously can't just be plonked into the roaster and roasted as normal. If one had a sample of freshly picked beans that one wanted to test roast immediately, the only way would be to dry them in an oven first. If you press into the bean with your fingernail do you get an impression?

The above concerns your original question which refers specifically to the high moisture. More generally of course there are many other factors which can increase or decrease the acidity. First is the type of bean - Sidamo is known as a bean with relatively high crisp acidity. Secondly and also with respect to the roasting profile, the level of roasting drastically affects the acidity in the final beans. Taken soon after first crack the acidity will be very high. By the start of second crack the acidity will be substantially reduced. If taken well into second crack most of the acidity will have been converted into sweetness and body. The proportions of time spent in the different roasting stages have a major effect on these changes. Also of course the grind and method of preparation will further affect the acidity in the cup.

Bhante


so spending time below 120 is to reduce sourc or reduce moisture?
 
Bhante

Quote

relacker wrote:
so spending time below 120 is to reduce sourc or reduce moisture?

By reducing moisture the coffee will be able to roast properly, and thereby will be less sour.
 
relacker
i tried with full blast of 250 degC with genecafe. reach 1C at 11min and roast til 13min still maintaining 250degC and then put it auto cooling for another 10min. the roast turn out all right and the sour taste gone!

here's the sidamo look, full city +?

img707.imageshack.us/img707/9823/sidamoroasted250degc.jpg
 
seedlings
Also, how are you brewing the beans? If your water is cold, under 190F, then the sourness can come from the brew, just as water too hot (above 205F) can cause bitterness.

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
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