I have been meaning to put together a corretto for a couple of years now but never got around to it until this month. Here are the benefits:
- cheap. equipment is cheap (see below) and super high quality unroasted coffee is ~6 bucks a pound. professionally roasted coffee is ~16 a pound.
- quick (about 15 minutes to roast a batch that will last a few days of regular consumption)
- high quality-to-dollar ratio. about 80-90% as good as professionally roasted coffee which is still 10-20x better than pre-roasted coffee. also higher relative quality than other cheap home roasting methods (like the air popper or skillet roasting)
- way more fun than buying coffee roasted by other people (if you are a geek like me) but still tastes great
the bread machine is an Oster from goodwill that was 25 bucks and has a mostly continuously agitating dough cycle. I never use the bread machine heating element -- just the enclosure and the agitator. the heat gun is an Ace hardware non-electronic simple model and was 20 bucks. the thing the heat gun is attached to is (I believe) a piece of photography equipment that I found at a flea market for 10 bucks. so 55 bucks plus another 25 for a few pounds of beans and valve bags.
I got a few different 1LB bags of green from sweet marias which happens to be across town from me so I picked up in person. they are super nice people! the detail shots are of a kenya gaturiri peaberry which ended up with lotsa defects after roasting, presumably due to the small beans and the somewhat aggressive agitator in the bread machine.
for cooling I used a colander that was set on top of a window mount fan that was laid flat. Need to improve on this design but it worked
next step is to get a thermocouple and build a PID with an arduino and some relays so that I can model the temperature profile ahead of time on a computer. It would be awesome to record the temperature curve for each variety I roast and post the data online so it can be discussed and forked by other roasters. I also have dreams of a fully mechanized bean loading and unloading/cooling process, as well as a pourover robot that I can set up next to my bed and use as an alarm clock of sorts.
a very basic outline of my roasting process (subject to change) is:
- turn on bread machine to a mode where the paddle will flip around pretty much constantly and set a fan up at a crosswind to blow away chaff
- put 300g of beans into the bread machine. try to cover the top of the chamber around the heat gun nozzle with something to keep the heat in. temperature control is the whole idea here.
- turn the heat gun on high and start a timer
- after 7-14 minutes depending on the type of bean the beans will start to making crackling sounds. a few minutes later they are done. if you go too long you will burn the flavor out of the beans. if you go too short you won't activate the proper level of chemical reactions inside the beans to release all the potential flavors and aromatic experiences :D
- now you have to cool the beans as quickly as possible. dump em out into something cool and apply cold air
- once they've cooled go through the beans and remove any beans that look unusually light, dark or broken (defects)
- put the coffee into a food safe container, preferably with a one-way valve or a way for air to escape but not enter. coffee gets stale and nobody likes stale coffee. but after roasting there is a buncha CO2 still trapped in the beans that makes the coffee taste less awesome. let it sit for a few days and it will be perfect. but don't be afraid to taste the coffee often as you are learning -- the flavors will change from day to day. after a couple of weeks it will start tasting crappy again.
- pick a method from brewmethods.com and go crazy!
all the notes from my research on the corretto are here: https://gist.github.com/4108551
one thing I learned that I didn't see in the research I did is that if you try to cover the top of the bread machine as much as possible then chaff is mostly taken care of automatically due to the interior design of bread machine chambers. so what happen is the chaff just kinda magically collects underneath the bread pan. I used a shop vac to quickly clean up the chaff after it cooled down. the chaff that did escape was blown out a window by a fan I had propped up next to the corretto. the chaff that stayed under the bread pan is easy to clean up with a shop-vac after the roasting process.