Roaster Modification Museum

[Hiroyuki]

This is another interesting topic offered by Nakagawa of Flavor coffee http://www.flavorcoffee.co.jp/index.html

(Japanese only)

Nakagawa is sometimes asked by customers to modify and improve their roasters. The Roaster Modification Museum page http://www.flavorcoffee.co.jp/3f/r-index.html (Japanese only) lists some of the roasters he has modified so far. Among the list is the Alpenrost http://www.flavorcoffee.co.jp/3f/3f-15.html . Let me translate part of his description of what he did about the roaster.

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Side view

With the cover open

Perspective view, with the cover open

Heater

Roasting, with the shutter closed

Cooling, with the shutter open

The roaster has several disadvantages.

First, you cannot visually check the beans to determine when to stop roasting.

Secondly, this roaster does not have the concept of murashi* (lit. steaming), resulting in light-taste coffee.

I think this is its biggest defect, a fatal one.

Air inlet slightly open (roasting phase)

Air inlet half open (murashi phase)

Close-up of the spoon with a thermometer attached

Close-up of the spoon retainer

I made three modifications so that the roaster allows the user to:

- Vary the exhaust air at will so that the concept of murashi can be applied.

I made a hole in the cover so that the amount of exhaust air could be controlled.

With the hole in the cover open, the roaster sucks air through the hole, so that the exhaust air from the drum decreases.

- Use a spoon to check the beans.

For this particular roaster, there is a flow of air inside the cover, so I had to plug the gap between the spoon and the cover.

- Check the temperature inside the roaster.

I inserted a tempura thermometer into the spoon so that the temperature could be measured except when checking the beans.

Results:

- The exhaust air-regulating function allows the user to perform "murashi" as with a commercial roaster.

By performing "murashi", the user can now prevent the coffee beans from losing flavor.

- The user can check the beans with the spoon to determine when to stop roasting.

- The thermometer assists in improving reproducibility.

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*Murashi (lit. steaming): With a direct-heat type roaster, it is common practice to restrict the exhaust port for some time after beans are put in and heated, so that the humidity in the roaster increases. This very initial step of the drying phase of the roasting process is called murashi in Japanese. I tried to find an equivalent term in English, but to no avail.

[Hiroyuki]

This page http://www.flavorcoffee.co.jp/3f/3f-5.html (Japanese only) is on modifying a home coffee roaster.

The biggest problem with this roaster is that the beans do not move due to the insufficient amount of hot air.

So, Nakagawa decided to attach a vane for agitation.

He also attached an aluminum plate as a damper for regulating the exhaust air, a thermometer, and an 'agitating ball' to improve the efficiency of agitation, and made some other minor improvements.

Edited October 16, 2004 by Hiroyuki (log)