How do I roast coffee at home?

The first thing you’ll want to do is fine a green coffee supplier who can provide you with a good quality bean – the old saying “garbage in, garbage out” definitely applies to coffee roasting. While you want to start with an inexpensive, forgiving coffee like a Brazilian or Colombian, you still want it to be fresh (this years crop) and free of mold/mildew/defects. Ideally, find a coffee roaster selling unroasted green coffee beans from their own roasting inventory.

Green coffee prices will vary by country and specific lots/crops within a country, and you will pay more for higher quality green coffee beans.

Coffee Roasting

From earliest times coffee roasting has been done in a frying
pan using a stick to stir. You can use a wok but it is a
difficult job keeping the temperature hot enough without
scorching (tipping) the beans, and this frequently provides an uneven roast.

An adaptation of the wok is the stove-top corn popper – a
saucepan with a lid and a stirring paddle inside turned by a
handle. These are commonly fitted with a thermometer by the home
roaster to assess the roast as it progresses. This method can
become tedious since you must continue to stir the green coffee as it

Popcorn Coffee Roasters

The next stepĀ  up is the electric popcorn popper. These are
available throughout the world with a very small investment –
and are often available in thrift/charity shops even cheaper.
They are very commonly used and were the mainstay of the
hobbyist roaster up to fairly recently. The procedure with these
machines is simply to add half a cup of unroasted green coffee beans and switch on.

They should start rotating immediately – if not give them a stir
until they lighten and turn themselves. After a while they go
yellow; then there is a distinct “cracking” sound (1st
crack.) and this will continue for a minute or so. Around this
time the chaff (white silverskin covering on the bean) will be
blown off. Continuing to heat them will gradually change their

The easiest way to judge the color is to have a sample bean of
the required color beside the roaster. If you want to roast
darker than Full City, you will get a 2nd crack. This is often
much quieter than 1st and you may miss it on your first attempt
or so. Just before the required color is reached tip the coffee beans
into a sieve/colander and blow air on them – or toss between two
sieves. As you get more experience you may want to control the
process more closely by weighing the coffee beans, using a timer,
thermometer mounted in the butter tray – gadgets limited only by
your ingenuity!

It should be mentioned that this method must we watched
carefully since the chaff can catch fire if it touches the
heating element.

Home Coffee Roasters

The final method is the factory built home coffee roasting machine.
These machines work on the same principle as the popcorn roaster
blowing hot air up through the beans – but they have a built
in timer, a cooling cycle at the end that cuts in automatically
and a chaff collection device at the top. The price of these
devices varies according to volume of coffee roasted and company
producing them

These machines have simplified the process drastically. When you
have the timer setting determined by practice, you can simply
stay in the area just to keep an eye on them in case anything
goes wrong as opposed to carefully watching the device and then
juggling the beans at the end of the process.

The total roasting process takes from 5 to 18 minutes depending
on the type of machine and degree of roast.

Recent new additions to the options for home roasters include a
true drum batch roaster similar to what many professional
roasting companies use.

There are at least a couple of companies fabricating gas grill
drums that are capable of one and two pound batches for the home
roaster who needs larger capacity.

Some of the people in the home roasting movement and many of its
early proponents are tinkerers. For this reason there are
numerous modifications to all of the above methods that have
been documented on the web.

There are some disadvantages to home roasting. First the chaff
can be an annoyance. Even with the collection devices on the
home roasting machines there is a fine dust that escapes the
trap. Secondly the smell can be offensive to some people. The
darker the roast, the more smoke is given off. An oily roast
will produce visible clouds.

Some home roasters have created venting systems above their
roasting positions, open windows, cooker hoods. You can find
info on these by searching the web. Many people simply go
outside or into their garage.

You’ll want to leave your specially roasted coffee as whole bean as long as possible, and grind it just before brewing with a proper coffee grinder for maximum freshness.

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