Microwave coffee roasting..

[psaigh]

Just for a bit of fun, i tried roasting some greens in the microwave.  This is still a work in progress and Ive posted the results on my blog

Pt1:
http://bluechipespresso.blogspot.com/2008/05/microwave-roasted-coffee-it-was-only.html
Pt2:
http://bluechipespresso.blogspot.com/2008/05/microwaved-coffee-roasting-pt.html

But heres a couple of photos of my first two attempts.

[Gavin1]

Re: Microwave coffee roasting..

O.o

just straight nuke em in a dish?

I reckon if you juice up the motor on the rotating plate ull get a better roast

[JavaB]

Re: Microwave coffee roasting..

This was tried in 2007 and also the previous year by various members here on CS..... these attempts all failed (and managed to damage various containers in the microwave as well :-[)

One of the problems you will have is that moisture content is typically uneven between beans in the same batch and even between regions of the same bean....

See the QLD roast off thread where it was discovered there were darker roasted areas within the beans (with conventional roasting methods)...... there is also a link there to an article by an advisor to the roasting industry..... and this is caused by uneven moisture content.....

So beans that have a higher level of moisture, or have regions which are more moist..... will absorb more microwaves.... get hotter and roast more..... where other areas will have a very low level of roasting.....

I have read of one successful microwave roast..... by placing the beans on material from a microwave popcorn bag (not sure if it still contained butter :)..... this absorbs the microwaves and radiates the heat into the beans.... or popcorn.... and the indirect heat roasts them!

http://www.gardfoods.com/coffee/coffee.homerst.htm

[psaigh]

Re: Microwave coffee roasting..

wow great, thanks!

[Dolcimelo]

Re: Microwave coffee roasting..

So beans that have a higher level of moisture, or have regions which are more moist..... will absorb more microwaves.... get hotter and roast more..... where other areas will have a very low level of roasting.....

Because of this fact, the maximum temperature most foods will reach is 100 C. This is insufficient to roast coffee beans at all, in the sense that we are looking for. It might be enough to disrupt the cell structure, especially since they are heated from the inside, but you will never end up with a roast suitable for making coffee. When the water has vaporised, no more heating from microwave excitement occurs. So, its hard to think of this as roasting at all. Coffee beans are not like nuts.

I have read of one successful microwave roast..... by placing the beans on material from a microwave popcorn bag (not sure if it still contained butter :)..... this absorbs the microwaves and radiates the heat into the beans.... or popcorn.... and the indirect heat roasts them!

http://www.gardfoods.com/coffee/coffee.homerst.htm

I think these popcorn bags have traces of metals in them, and give a frying pan effect, transferring the heat radiantly and by some conduction.

matt

[psaigh]

Re: Microwave coffee roasting..

Because of this fact, the maximum temperature most foods will reach is 100 C.

Well, 100 C is no where near enough to melt the containers like my samples of coffee did. Pouring boiling water into those containers would be enough to melt them, which is definately not the case. So the coffee definately reached a temp much much greater than 100 C.

I think these popcorn bags have traces of metals in them, and give a frying pan effect, transferring the heat radiantly and by some conduction.

Are you sure? Metal and microwaves=big big sparks. Conduction (of any sort) and microwaves=run for the hills!!

[Dolcimelo]

Re: Microwave coffee roasting..

Well, 100 C is no where near enough to melt the containers like my samples of coffee did. Pouring boiling water into those containers would be enough to melt them, which is definately not the case. So the coffee definately reached a temp much much greater than 100 C.

Well, Im no engineer. Maybe theres another effect going on. But, unless the radiation is exciting something other than water molecules (which may be possible), it is hard to see how the temperature could rise much above 100 C.

I think these popcorn bags have traces of metals in them, and give a frying pan effect, transferring the heat radiantly and by some conduction.

Are you sure? Metal and microwaves=big big sparks. Conduction (of any sort) and microwaves=run for the hills!!

Pretty sure thats how they produce the effect. Dont worry too much about sparks. It depends on how much metal there is. For example, I have some nice old tea cups with gold around the rim. They will spark a bit, and get a bit warm, but the house is still here (I dont tend to do this to them, though). Large amounts of metal would not be a good idea, but putting some foil around thin bits of chicken, for instance, will shield them and stop them overcooking.

matt