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The Exothermic Headache (Solved)
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RayTCoffeePro
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RayTCoffeePro
Joined: 1 Jun 2014
Posts: 85
Location: For My Safety, Its Empty
Posted Sun Jun 8, 2014, 3:44am
Subject: The Exothermic Headache (Solved)
 

At the end of roasting green coffee beans, it becomes exothermic (gives off heat) , Without proper cooling it will roast even when its removed from the drum.

Do you guys have any suggestions for a highly ventilated cooling method?

Thanks,

 
Only true passion and expertise will make the best coffee.
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BoldJava
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BoldJava
Joined: 2 Jun 2006
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Location: St Paul, MN
Expertise: I love coffee

Espresso: '82 Oly Cremina 67
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Roaster: RK Drum and Gene
Posted Sun Jun 8, 2014, 6:02am
Subject: Re: The Exothermic Headache
 

I cool my beans in two ways, depending on the roaster I have used:

Gene Cafe.  I use the "E" stop, pull the beans.  Dump into a colander which is screwed into a 5-gallon bucket.  The bucket is attached to a $25 shop vac which cools the beans to room temp in 60 seconds.

RK Drum.  I assembled a simple 24" by 24" wood frame with a screen on its base.  I lay that on top of a $15 box fan and away we go.  Ambient temp in about 90 seconds (2.5 lbs of beans).

 
"On the trail for the goats' grail..."

Dave Borton
St Paul, MN
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CoffeeRon
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Joined: 26 Apr 2009
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Location: Eatonville, Wa
Expertise: I love coffee

Espresso: Wega Lyra, Europiccola(still...
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Vac Pot: Sunbeam CoffeeMaster
Drip: Melita BCM-4
Roaster: FR SR500,B-1600, SC/TO
Posted Sun Jun 8, 2014, 8:09am
Subject: Re: The Exothermic Headache
 

Home Roasting Supplies- the FreshRoast people- have one I've been tempted to buy even though my five Gal. bucket/shop vac. work just fine... Just because it looks so good. And it's made in the USA!

Click Here (homeroastingsupplies.com)

I can't speak for it's efficiency as I haven't used it though.
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boar_d_laze
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Joined: 21 Nov 2006
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Location: Monrovia, CA
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Roaster: USRC Sample Roaster
Posted Sun Jun 8, 2014, 11:11am
Subject: Re: The Exothermic Headache
 

The first exothermic period begins just before 1stCs (1st Crack Start) and ends at some point during rolling first.  Assuming you roast to City or darker, it's over long before Drop.  

The second exothermic period begins with 2dCs, at around FC (full City).  Once extothermia begins, cooling the beans will not quickly end it because it's caused by an internal chemical reaction and not by heat.  

However, as a rough rule of thumb, and up to the point where your blowing so much air through them that you're drying them out, the quicker you cool your beans post Drop the better.  

Rich
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OregonCityMan
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Location: Portland, Oregon
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Posted Mon Jun 9, 2014, 10:17am
Subject: Re: The Exothermic Headache
 

Along the line of what BoldJava posted, I have a commercial roaster and a DIY stainless steel pot roaster. Neither of them are equipped with a method to cool the beans. The Torrefattore commercial roaster was made in 2005, and the manual instructs you to turn the cyclone fan on when you reach the end of the roast. This is a classic exothermic headache, as it took five minutes to cool the beans to 100C. I only tried it once.

I manufactured a cooling frame, which I have pictured below. My design allows for the beans to be cooled in less then one minute. It has two drawbacks I should mention. It is not for indoor use as the large room fan will instantly disperse the remaining chaff from the beans. In my case they just blow out into my driveway, never to be seen again. Lastly, if you don't already own a large fan, then you have to purchase one.

The frame is any wood of your choice, and the screen is aluminum screen door material.

I will make another frame out of three inch tall material next time, as I have to be very careful with the room fan, as it can blow beans over the frame and onto the floor.

OregonCityMan: DSC03238.JPG
(Click for larger image)
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Frost
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Frost
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Posted Mon Jun 9, 2014, 5:12pm
Subject: Re: The Exothermic Headache
 

boar_d_laze Said:

The first exothermic period begins just before 1stCs (1st Crack Start) and ends at some point during rolling first.  Assuming you roast to City or darker, it's over long before Drop.  

The second exothermic period begins with 2dCs, at around FC (full City).  Once extothermia begins, cooling the beans will not quickly end it because it's caused by an internal chemical reaction and not by heat.  

........

Posted June 8, 2014 link

I have only ever heard of one exothermic event during coffee roasting: during first crack. Per this excellent reference by Carl Staub, second crack is a breakdown and destruction of the bean cell structure, but is not exothermic.

http://www.sweetmarias.com/roast.carlstaub.html

The next exothermic event after first crack would then have to be combustion.....
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boar_d_laze
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Joined: 21 Nov 2006
Posts: 1,314
Location: Monrovia, CA
Expertise: I live coffee

Espresso: La Cimbali M21 DT/1 Junior...
Grinder: Ceado E92; "Bunnzilla"
Vac Pot: Royal Coffee Maker
Drip: Chemex + Kone; Espro Press
Roaster: USRC Sample Roaster
Posted Mon Jun 9, 2014, 7:08pm
Subject: Re: The Exothermic Headache
 

The second step is followed by a short endothermic period which is followed by another exothermic step called the second crack.  This second pyrolysis occurs between 225-230C, and the roast color is defined as medium-dark brown (Agtron #50-45) (Davids, 68-69).  The second pop is much quicker sounding and the beans take on an oily sheen.

cf Coffee Research; and of course, Home Coffee Roasting, Kenneth Davids

Rich
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JGG
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JGG
Joined: 31 Mar 2006
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Location: Kentucky, US
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Posted Mon Jun 9, 2014, 7:34pm
Subject: Re: The Exothermic Headache
 

OregonCityMan Said:

The frame is any wood of your choice, and the screen is aluminum screen door material.

Posted June 9, 2014 link

Will any canola oil do?

Jim
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oldgearhead
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oldgearhead
Joined: 25 Jan 2010
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Posted Tue Jun 10, 2014, 6:00am
Subject: Re: The Exothermic Headache
 

Cooler = 5x5x2 Schedule 40 tee + shop vac

oldgearhead: CoffeeCooler3.jpg
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RayTCoffeePro
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RayTCoffeePro
Joined: 1 Jun 2014
Posts: 85
Location: For My Safety, Its Empty
Posted Wed Jun 11, 2014, 2:39am
Subject: Re: The Exothermic Headache
 

Thanks guys, though i would try with the method of using a mason jar and submerging it in cold water.

Highly ventilated means more air, So yeah oxidization wise i should try the mason jar trick.

(I was told by a local roaster that there should be no air contact when cooking).

(EDIT: Worked well, I know it's insane and unlikely, Just look at my latest post)

 
Only true passion and expertise will make the best coffee.
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