roasting green coffee beans

[fornax hominus]

I've been roasting coffee in a brick ovens for 4 years using 2 dollar store sieves clamshelled together with a skidplate and handle welded on. it works great! you can keep the beans in motion without them scattering. I get my beans by mail , shade grown , fair trade , organic and they only cost me $4 per lb [if I buy 20lbs] from Greenbeanery [even cheaper if you want conventional beans]. Right now I am 1/2 way through a 50lb bag of Peruvian beans .. lovely.
A tip: the beans keep on cooking [and darkening] for several minutes after you take them out to cool , so pull them out before they get to your favorite roast colour.

[Ken524]

Re: roasting green coffee beans

Fornax Hominus,

Neat idea! What temp is your oven when you roast and how long do you usually roast them for?

Nice looking oven, by the way!

[brickie in oz]

Re: roasting green coffee beans

Great idea....
Id like to know what temp too, with the cooling down, dont the commercial places drop them in water to cool them, or spray them or something?

Im going to give it a try for sure..

[Rastys]

Re: roasting green coffee beans

fornax hominus
I envy you with your roasting and has got me interested.
It would help to finish off a great pizza cook with fresh roasted coffee beans and wonderful fresh coffee to top off the night.
I will have to source some 'green beans' from around here.
Can you share some of your experiences/pitfalls, etc so that we (speaking for other interested people) may be successful.
I have been studying a book on cofffee beans, roasting, griding, brewing and serving a variety of coffees and keen to extend my skills to home roasting.

Cheers.

Rastys

[fornax hominus]

Re: roasting green coffee beans

Coffee likes it pretty hot , in my oven the soot is burning off the crown of the dome and the oven going full bore for about 1 1/2 hrs . As you see in the photo I like to sweep the coals right and left so I can get the flame/coals radiating from all sides. If your oven is hot and you don't have too much coffee in the sieve it takes about 10-12 mins .. of course I put as much coffee in the roaster as I can get [1 1/4 lbs] so it takes 12-15 mins.
It's really important to keep the beans moving to ensure a even roast. With the clamshell design you can time your shakes so the beans hit the inside top and cascade back towards you .
It's sort of like popping corn , indeed the first roasting I did was was in a $8 electric hot air popcorn popper.[ works ok, burns out in a few months] .
As you shake the coffee it goes through changes , first it expands ,gets a tan and throws off the first skin . This will shake out through the sieve and start to burn on the oven floor . As the process continues it gets darker, expands again , throws off the final skin , which again falls through the sieve, now the beans are getting oily and they are starting to smoke and smell really bad [ kinda like a sofa on fire].. Here comes the "goldilocks " moment .. If you want a light roast .. you may already be too late , as I stated in my first post when you haul them out they will continue to darken .. My friend John came up with the technique of taking the beans out early , piling them in a smoking mound on the cookie sheet , waiting for 1-2 min then shaking the sheet out to stop them cooking . I have put them on screen to get air moving through the beans , it's a bit of a trade off , the cookie sheet gets really hot from the beans on it , cooling off the beans that way.
When the beans stop smoking , all of a sudden ... a miracle! they don't smell like burning wrestler's trunks anymore, they now smell fantastic !!
Note: do not seal them up right away , coffee beans, depending on the part of the world they come from, variety etc. can take up to 32 hrs to de-gas c02 [ Starbucks and other shipped beans have to pre-stale their coffee so It won't blow up those foil bags ].
I know I am a bit ''over the top'' with all this , but when you have had your own roasted coffee you cannot believe how good it is .
The link I provided to the green beanery has all kinds of info on coffee.
Last night , more coffee, 3 loaves of oat bread, a pan of oven fried potatoes and a roast beef that we will cut up for lunches next week . Roll on oven!

[Rastys]

Re: roasting green coffee beans

fornax hominus
Thank you for your comprehensive explanation.
I will source some and give it a go.
How do you thing a stainless woven barrel rotiserie style carrier would work rather than the clamshell that you use?
It looks from the pics to be spherical rather than cylindrical!
Obviously it needs to be kept revolving during the roasting process.
I just need to workout how to make one which joins to hold all the beans but allows the skins to pass through (but I guess that they are thin, brittle and break up easily).

Cheers.

Rastys

[fornax hominus]

Re: roasting green coffee beans

Rasty,
When you are dealing with dollar store any thing, quality is not an option . My 2 sieves used to be more round.
There are 3 brick ovens in my ''hood'' and we all dream of more efficient ways of roasting coffee than standing , shuffling and shaking [esp. in the winter] , but so far the rotating basket has not emerged.
You are right, the skins /husks are very brittle and break up to come through the fine mesh of the sieve .
My friend uses an open stainless steel collander , it requires more control so that you don't scatter beans all over the oven floor , but because it is open on top gets more radiation from the dome and roasts faster.
Whatever device you come up with you really want to be able to see into it to be able to judge the colour , and to be able to release it fast enough to empty the beans out.
I forgot to mention in my last post .. green beans keep for years! Roasted , only a couple of weeks. So you can keep various kinds and enjoy them at their peak , whenever you want!

[fornax hominus]

Re: roasting green coffee beans

Rasty,
When you are dealing with dollar store any thing, quality is not an option . My 2 sieves used to be more round.
There are 3 brick ovens in my ''hood'' and we all dream of more efficient ways of roasting coffee than standing , shuffling and shaking [esp. in the winter] , but so far the rotating basket has not emerged.
You are right, the skins /husks are very brittle and break up to come through the fine mesh of the sieve .
My friend uses an open stainless steel collander , it requires more control so that you don't scatter beans all over the oven floor , but because it is open on top gets more radiation from the dome and roasts faster.
Whatever device you come up with you really want to be able to see into it to be able to judge the colour , and to be able to release it fast enough to empty the beans out.
I forgot to mention in my last post .. green beans keep for years! Roasted , only a couple of weeks. So you can keep various kinds and enjoy them at their peak , whenever you want!

[Rastys]

Re: roasting green coffee beans

fornax hominus,
I am more keen than ever to make the roaster cylinder as in the .pdf attached.
The mesh I am trying to show could not be downloaded from Locker Group - Expanded, Perforated & Wire Products
and is fine woven 304 or 316, 18-22g stainless wire, hinged to allow for easy and quick emptying of the beans onto maybe a cold or cool granite surface or kept within the basket and hit with a high volume cool air jet, similar to what is used to temper shatterproof glass. I would think that a half kilo would be all I need to roast at any time in a 250mm (10") x 500mm (20") long cylinder.
What are your thoughts?

Rastys

[fornax hominus]

Re: roasting green coffee beans

Rastys,
Looks great! Me want! I like the variable wiper motor idea ,.. [the Ford Ranger's I have had seem to have the most settings]
The cold slab will work , the beans do tend to scatter and you will have to clean the oily residue off the stone . I don't know how hot the beans are when they finish , [hot enough to melt the plastic hopper on a coffee grinder .don't ask ...sigh!] but probably +500f..
For 6 months of the year we have snow and I can rest the cookie sheet on that , probably not an option for you in the antipodes.
The beans do lose a bit of weight in the roasting process , so if you start out with 1/2 kg you will probably get a scant lb.

[Rastys]

Re: roasting green coffee beans

I will source the stainless wire this week and have a long weekend coming up to make it all.
I have plenty of wiper motors as I work sat mornings in a wrecking yard and get them for free as they never sell.
Hooked up through a variable rheostat, you have infinite speed control, so set it to what you feel is suitable.
Thanks for your input, muchly appreciated and will get back with the progress made as we have a large pizza cookup and now fresh roasted coffee for the espresso machine on 28 June.
Cheers.

Rastys

[Rastys]

Re: roasting green coffee beans

fornax hominus
Well, we're making progress. I tried to get some stainless wire mesh but was pretty expensive, had too come from interstate, would take a week or so to arrive and they wanted too much for a simple delivery, so I sourced some small aperture expanded steel sheet.
I bought an off cut with enough to build another 2 roasters for $36. Came home this afternoon, cut the sheet and folded it, I thought that a hexagonal one would be easier to make (as I don't have a set of rollers to form it properly), but would aggitate the beans better whilst roasting.
It took around 2 hours to make and I plan on a rotisery base with provision for a tray to slide in under the roaster for when I use the set-up as a rotiserie.
I can't see the point in making some thing for a single purpose and by putting a stainless shaft into the base will become a rotiserie for that side of lamb or smallish pig.
The opening method is simple, with just a single wire pin pulled out from the 4 protruding lugs and hey presto, it's fully open.
It measures 400mm long and 200mm diameter and should hold several kilos of beans but I only plan on roasting a kilo at a time.
I have left a protruding lip in the roaster to aggitate the beans and can add others if needs be.
All it needs is a bake and a lick with some steel wool to clean it up a little.

Rastys

[Rastys]

Re: roasting green coffee beans

All done!
Now it needs cleaning a little, some good green beans and a hot oven.
I decided to make the stand to stand inside the oven and be used as a rotiserie as:

http://www.fornobravo.com/forum/f35/...erie-4352.html

I made it adjustable height, to fit easily through the oven opening and can be used for a roaster or change the shaft to a stainless for a rotiserie capable of an 850mm long cook. There is also access for a tray to slide in to empty the beans or a drip tray for the rotiserie.
I will need to cut one small semicircular holes in the oven doors so that the heat can be contained within the oven when the shaft is protruding through. I also need to insulate the drive motor from heat for the longer bakes.
I did not fit a motor yet as I will hand crank it for the roaster initially whilst I think the motor/drive system through. This is not a very long time as I have been studying up on coffee bean selection and roasting.
Neill has a couple of ideas but I need to take into consideration the adjustable height, viewing access into the oven past the drive set-up and also safety factors.

Rastys

[fornax hominus]

Re: roasting green coffee beans

Rastys
Oops, my post yesterday must have fallen under the bus ... I noted that your octagonal design will expose more beans to the heat than a cylinder which would require baffles to stop them sliding to the bottom as it rotates.
I can see where you want your door shut for the rotisserie operation , but for coffee the thing about roasting with open door and the fire still going is that you visually have to check how things are going towards the end .
As well different factors come in to play , type & quantity of of beans, temp. of the oven , and with me [not you] the outside air temperature [I have roasted beans @ -20c .. not fun!!].
Great work on the roaster!

[Rastys]

Re: roasting green coffee beans

The hexagonal design has only one baffle/paddle at present, at the hinge, but I can very easily add more or even angled smaller ones to mix the beans up more. The ones sliding around the ends of the roaster could be chanelled onto the centre and visa versa. I just want to keep the open edges free from baffles for ease of emptying the beans.
I have just joined a coffee forum for more advice and to get a few answers to my brewing/espresso making.
I will get that exceptional brew yet.

Rastys