Home Roasting with I-Roast and others from green to roasted coffee bean

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Types of Domestic Roasting

There are a number of products that do small roasts, you can roast on an open pan, like they do in Ethiopia and how they discovered to roast originally. This method is time consuming, and can typically so no more than 90g of coffee at a time.

Diary of a Home Roaster

After spending a few attempts with pop corn poppers and oven pans it was decided to try and use some of the specialty home roasting products

This page is dedicated to experimentation done with roasting quality green bean with a home roaster. Have you done some roasting at home, send us the details and we will share them.

I-Roast 2

The below are the tests done with a I-Roast 2 home roaster.

This roaster is essentially a mini fluid bed roaster. A heated element is set to a temperature and the air up past the element blowing the beans up and thereby rotating them. so that they all should get a relatively similar level of exposure.

The I-Roast is one of the leaders in the domestic market, and is a good place to start, since it can technically do up to 150g of coffee at a go.

It can roast for a maximum of 15 minutes, and has 5 programmable temperature levels.

All these tests where done in Cape Town, so the roasting is at sea level. Humidity, altitude and weather dictate the minor differences that may occur in the roast

Date	Bean Rstd	Green Wght	Phases	First Pop	Second Pop	Total	Final Wght	Rating	Comments
30 Sep 07	Mzuzu (Sample)	90g	1:160°C; 4:30 2:176°C; 0:30 3:190°C; 0:30 4:200°C; 1:00 5:210°C; 2:00	04:30 (started)	02:00 (I think)	07:30	66g	burnt outside, semi raw inside, yuk. This is what happens when you use retail grade stuff.	Stopped the roasting cycle early since the bean was looking burnt
5 Oct 07	Marango	70g	1:160°C; 15:00	08:34	11:21 to 10:09	07:30	62g	almost right, perhaps Agtron all right on the outside, drinkable	Pressed Cool button at 07:30 to stop over roasting
6 Oct 07	Marango	90g	1:160°C; 07:00	03:20	4:05	07:00	76g	Quite nice, about as close as the Marango roasted using the Diedrich	I think this is about as good as you can get.
9 Oct 07	Marango	150g	1:160°C; 07:00	03:10	4:55	07:00	126g	Drank it fresh from the roast quite good	Now more or less convinced this is about as good as you can get out of this little roaster.
15 Oct 07	Yirgacheffe	90g	1:160°C; 06:40	03:25 to 02:40	n/a	06:10	78g	Even though Second pop had not started, it was creamy and not dominated be lemon	Roasting stopped before second pop started

Further Roasts

Date: 17 July 2009

We took one of the new crop of Limu and did three different roasts. Using the I-Roast feature of phases. The basic principles of the roast was this:

Ease the bean into the roast slowly by putting at the lowest temp. for as long as possible
Increase the roast temp. in a varied amount so that when typically the first pop temperature of around 200°C is steady
Experiment with short bursts of the second pop temp. typically 220°C

We then sampled the roasts, and found that 4 and 5 below produced the most flavoursome roasts, and combining the two produced a slightly different coffee too

Program #	Time 1	Temp 1	Time 2	Temp 2	Time 3	Temp 3	Time 4	Temp 4	Time 5	Temp 5
2	4:00	160°C	1:00	180°C	0:40	196°C	0:40	210°C	0:40	220°C
3	4:30	160°C	0:30	180°C	1:30	200°C	01:30	220°C	-	-
4	4:00	160°C	1:00	180°C	1:30	200°C	01:30	220°C	-	-
5	4:30	160°C	1:00	180°C	1:30	210°C	01:30	230°C	-	-

Interested in an I-Roast? Contact us, or go to Orders and order one, and a few green beans too.

Other reports

Below we will add reports compiled by other Home roasters. As each each person submits we wil publish, with little or no editing.

Antonie van Wyk

Date Submitted: 5 May 2010

One requires no fancy equipment to roast green coffee beans.  Apparently popcorn machines are very popular and I've even read about someone that uses a pot and a paint stripper (the one that looks like a hairdryer) to roast his beans!  For the undiscerning coffee drinker the result should be more than acceptable.  Yes, it is more schlep than buying roasted beans at the supermarket, but the cost saving, great taste of the freshly roasted beans and the fun of doing it oneself outweighs the hassle for a good number of people.

The only problem with the low budget methods described above are that they are quite messy.  As the beans reach a certain temperature, the oils inside the beans start to cook and gasses are released causing the beans to expand with an audible crack.  In the process the external layers of the beans detach as chaff and often some smoke is released.  You'll have to spend a bit of time separating the chaff from the beans once you've finished roasting in the popcorn machine, whilst using the pot version will probably require a good clean of the work space afterwards.

I haven't tried it myself, but I suspect that the popcorn machines will not be up to the task of producing a particularly dark roast, whilst the paint dryer alternative runs the risk of scorching the beans.  Personally I prefer a milder roast, so the popcorn machine version would probably have done the trick for me.

I'm fortunate to have received a Gene Cafe automatic roaster as a gift so have never had to explore the budget alternatives.  I'm not sure whether it's available locally, but there are a number of machines on the market in South Africa should you wish to upgrade from the popcorn machine (ED: it is available here, cost at time of publishing is about R4,800).  The Gene Cafe is an entry level roaster, but is extremely capable and easy to use.  The results that I have achieved so far are very satisfying.  In theory one can set the temperature and time of the roast, but in practice one invariably needs to use the maximum temperature (250C) as the machine will never get there anyway and timing is often a bit of a hit and miss affair.  The difficulty is that roasting times depend on the type of bean and of course how much is being roasted.

The name of the game with my machine is to keep your eye on the beans to gauge the correct colour, to listen for the first (and sometimes second) crack and to smell the aroma.  The machine typically reaches approximately 230C by the time the beans are done, and roasting times are normally somewhere between 17 and 21 minutes.  I normally hit the 'off' button manually, and the machine then goes into the cooling phase.  Here's where it gets a bit tricky as the beans continue to roast during cooling, so I've got to anticipate and stop early to compensate for it.  Sounds a bit vague, but I've actually managed to get the roasting times down to a couple of seconds for different beans given similar volumes.

The more expensive machines measure the roasting temperature more accurately and employ more effective roasting and cooling techniques, which makes for a more scientific approach, but if you want my opinion, your average home roaster will never be able to taste the difference.  I certainly can't.

The jury seems to be out on whether beans should be blended or not.  I prefer not to blend as I quite frankly have no idea where to start and have no reason to as the singe beans taste great anyway.  There are quite a few purists that insist that blends should only be used for inferior beans, so that argument works for me (or am I rationalising?)

For me, roasting is not only a very fun hobby (I enjoy gadgets!) but also very satisfying when I taste that first cup of home brewed coffee or see the looks on the faces of family and friends when they taste decent fresh coffee that is often much nicer than the restaurant versions.  Too me, life is way too short not to have good coffee!

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