roasting green coffee beans

[deejayoh]

Re: roasting green coffee beans

Sounds like quite a contraption Neill, but with all that work, I have to say that my Behrmor is looking like a pretty efficient investment

I do love having home roasted beans though.

For those of us in the US, check out Sweet Maria's as a source for beans.

[Laurentius]

Re: roasting green coffee beans

Sounds like quite a contraption Neill, but with all that work, I have to say that my Behrmor is looking like a pretty efficient investment

I do love having home roasted beans though.

For those of us in the US, check out Sweet Maria's as a source for beans.

Hi Dee,

I'll have to agree with you, our Behmor is a far superior and efficent machine and probably cheaper. I live in and still get my beans from Sweet Maria's.

[Laurentius]

Re: roasting green coffee beans

Laurentius



Once I collected the old bottle, outdated 1997, it only took a half day to cut the bottle in halves, (ensuring that it was totally empty and not likely to explode nor catch fire, but if I were to do it again, rather than cut it through the centre weld, I'd cut it around 40mm higher), weld on the hinge brackets, using a hole saw, cut holes in the base for air ventilation and to protrude the gas ring, cut and fold the basket and handle then bend, drill and weld the basket supports. The only other task was to drill and tap the top brass ex-valve to hold the thermocouple, (this was later lowered to beside the rotating basket.



There seems to be no distinct lull between 1st and 2nd crack, so that is where time and temperature control is important. By putting in the side of the basket a patch of woven stainless steel wire mesh to visibly see the bean colour is so important because if I lift the lid, then a lot of the heat escapes and becomes uncontrollable!



This is my best indication of roast done! The first sign of the blue smoke means all over and cool beans immediately. There seems to be no smoke from the burning chaff that I can detect but see the ash falling out of the basket and through the gap of the 2 bottle halves.



That is why the recording and time/temperature determination for my ideal roast is so important for consistency. The making of a new drum/basket with larger holes and thicker material, 1.6mm (16g) allows more chaff to escape and burn, also easier to weld and hinge, BUT being heavier, draws more heat out of the dome and takes a little effort to maintain the required.desired temperature.
I can remove the basket from the roaster and dump the contents into a large thick aluminium roasting pan in less than 20 seconds and then float the lot in a shallow sink of cold water, bringing the beans to room temperature in a minute or so. Just looking for a small battery (or even 12v motor to rotate the basket/drum, but unlike a rotiserie, I want at least 30-60 rpm rather than the 3rpm average of rotators. A windscreen wiper motor is looking good but I would prefer a small battery unit rather than a 240v transformer reduce to 12v set up.

Cheers.

Neill

Hi Neill,

I feel that if there is no lull time between 1st and 2nd crack, that you do not have sufficient control of the beans profile. With any given bean you should be able to roast it during 1st crack to(City, City+ or Full City, just before 2nd crack), after the onset of 2nd crack, you should be able to obtain(Full City+, Vienna, and French roast), when you see divots or crater in your beans you have passed the natural profile of the bean. Smoke is an indication of the beans sugars are being burned off, not an indicator that the beans are done. There are many coffees that are excellent at a few seconds of 1st crack, even some espresso blends need not to go dark. Don't you think that if your beans were rotating a 30-60 rpm, that the centrifugal force would move the beans as a solid mass and not in the tumbling random fashion needed to roast each bean, more or less uniformly?

[deejayoh]

Re: roasting green coffee beans

I think Vienna Roast = small charcoal briquettes

Full city+ is about the furthest I find I it reasonable to go without obliterating the characteristics of the bean

there is a really nice pictorial guide to roast levels on the sweet marias site

A Rough Pictorial Guide to the Coffee Roasting Process

[cuveelouise]

Re: roasting green coffee beans

Hey there, I'm a total noob lurking on the internet who has never used a wood oven or roasted coffee in his entire life, but I think you're all doing this completely wrong and are "wasting" your time building beautiful and ingenious but ultimately unnecessary rotisseries. Is what I'm about to say stupid? (sure sounds like it after that sort of introduction!) Has anyone tried it?

It seems like everyone just looked up how to roast coffee and is trying to replicate commercial coffee roasting procedures inside their oven whereas the process should actually be quite different as the heat is being applied in a different way. Rather than blindly copying how coffee is roasted in a commercial roaster we should reconsider the process as best suited to a wood oven.

The whole idea of moving the beans about is to get an even roast and the whole idea of having a high thermal mass, insulated wood-fired oven is to get nice, even heat. Why not just completely remove the coals, spread the beans out over a flat, thin mesh tray (raised off the oven floor using the thinnest mesh possible with gaps that are wide, but just small enough that the beans don't fall through) so they don't touch each other and "shade" each other from the radiant heat and just let the oven do its job of even cooking? Commercial roasters have to agitate them or blow hot air as they have uneven heat and need to move the beans, otherwise they would burn. All their complicated procedures are just trying to get that even heat and temperature control that your oven already has and putting the coffee beans inside a metal rotisserie inside the oven is actually taking a step backwards-the metal rotisserie re-creates uneven heat and so you have to turn it to try to even the heat back out - the only problem it solves is one it creates! Obviously if you put the beans in a heap or pile it wouldn't work at all since the ones on the outside would get all the heat and burn but if they are spread out it should actually work better than a complicated rotisserie system, right? It seems like oven roasting procedures are better for a wood-fired oven and you wouldn't have the problems with smoke and uneven roasting that usually make oven roasting a less-than-ideal option.

Can somebody explain to me why that wouldn't work? Has anyone tried it that way? Seems like a no-brainer to me but I can't try it myself as I still haven't built that oven...

- le frenchman arrogant

[Ken524]

Re: roasting green coffee beans

Cuveelouise,

You're crazy! Blasphemy! You don't have an oven and you've never roasted coffee beans?

I have an oven, but have never roasted beans (I'm very interested in trying). Your idea makes perfect sense to me. As you said, our ovens are perfect at providing even, radiant heat.

Unless there is another reason why coffee beans need to be jostled around while roasting, I don't know why a flat screen held up by a few bricks around the edges wouldn't work.

Great idea and thank you for contributing. Now... do you think we can convince you to build an Italian brick oven in your backyard?

[Lacehim]

Re: roasting green coffee beans

Well I have roasted beans in my WFO and I can tell you that they still need moved around if you are doing large batches 250g+. I used 2 colanders strapped together and if you didn't keep them moving some beans got burned before others had even started the process.

Coffee needs to be roasted at a higher temp than you might think, 200-230oC. I use a KKTO at home, and load the beans at 150oC with 600gm green on full heat, and the heat will take around 16 minutes to roast to 1st crack, then you need to coax the roast to 2nd crack without it happening too fast or too slow to develop the flavour in the roast. You then need to cool it quickly to stop the roast going too far. I've been roasting for a few years and I'm still learning!

I'm not sure if your oven would have enough residual heat to continue a 15+ minute roast to 2nd crack without any coals. Also if the roast it's uneven you'll have half burned beans, and have undercooked beans which will lead to some interesting flavours in the roast I can tell you!

With the colanders I had a few successful roasts, but it was a lot of work to keep moving. I'm not saying your idea woudn't work, but you would have a lot of factors to take into account. 1 your trays would have to be off the floor, and not too high, and able to be easily removed too cool. Your temperature will have to be monitored some how to make sure you were in the 230oC range and able to keep that temp for 20+ minutes while you roast.

If you've every roasted at home and his 3rd crack you'll know how much of a disaster than can be! lol. The WFO roast was unique though, and the smokey wood carried across to the coffee, and my batches were quite drinkable. I have the components to build a roaster that loads into the oven, but haven't got around to finalising the build.

If anyone is willing to give cuveelouise's idea a go it would be an interesting experiment though.

[jeeppiper]

Re: roasting green coffee beans

Monsieur Frenchman Arrogant does make an excellent point that commercial coffee roasting procedures should not apply to roasting coffee in the WFO. In my humble opinion, roasting on flat sheets would work, however I do not believe that you will have good control over the roast itself.

1. I don't think your beans will roast evenly. Since the beans will be sitting near the oven floor, the heat radiating from the floor will be very intense, whereas the heat radiating from the dome will be much less intense. The result will be burned bottoms and unroasted tops. You would be better suspending your trays in the middle of the oven...somehow. Similarly, beans sitting near the walls will receive more radiant heat than those placed near the center of the oven. Those near the entranceway will receive much less radiant heat.

2. You will likely need to close the oven with an insulated door. Otherwise, cool air will circulate through the oven opening and across the oven floor. This will further cool the tops of the beans and cause them to roast unevenly. Closing the oven door will also make it difficult to monitor the progress of your roast. Monitoring the progress of the roast is all about sight, sound, and smell...(and time and temp).

I have spent the past couple of years roasting coffee in my WFO and I can tell you based on my experience that knowing the temperature of your beans is much more important than knowing your oven temperature. I have a thermocouple integrated into my roasting basket which monitors the bean temperature rather than just the oven temp. Once I started using this thermocouple, my roasts come out perfect every time! Once you hone your coffee roasting skills, you can never go back to drinking commercial coffee again.

Give the tray idea a try and see how it comes out.

[deejayoh]

Re: roasting green coffee beans

Commercial roasters have to agitate them or blow hot air as they have uneven heat and need to move the beans, otherwise they would burn. All their complicated procedures are just trying to get that even heat and temperature control that your oven already has and putting the coffee beans inside a metal rotisserie inside the oven is actually taking a step backwards-the metal rotisserie re-creates uneven heat and so you have to turn it to try to even the heat back out - the only problem it solves is one it creates!

I've been home roasting for 5+ years. On my third gen roaster. AFAIK, Commercial roasters are built for even heat distribution. They are purpose-built devices with one goal: roasting coffee. Turning the beans ensures that all sides are roasted evenly.

IMHO it's folly to suggest that a WFO somehow provides more even heat than a coffee roaster. WFO heat is difficult to manage in small precise increments, and not terribly even. You can't cook a pizza in a WFO without turning it. I'm not sure what it would do to a coffee bean.

[jeeppiper]

Re: roasting green coffee beans

I have learned to use the "uneven heating" of my WFO to my advantage when roasting coffee. Again, I can monitor the temperature of the beans themselves rather than just the oven (thermocouple is buried in the batch of beans). When I want the beans to roast faster, I move the upper reaches of the dome where it is hot....I can cool them off mid-roast if I feel that they are roasting too fast by moving them into the entranceway....or, even take them out of the oven completely for a few moments. My beans turn out evenly roasted every time.

All this coffee-roasting talk is making me want to roast some more....(I just did 6 pounds on Saturday). I crave that smell !!!