A Multi-Use Roaster?

2010 January 28
by Joe Johnston
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I am contemplating making the roaster a multi-use roaster, specifically a roaster of coffee, cacao, grain and (possibly) nuts. It seems to me that if the operating envelope of the roaster is made broad enough, it would be quite suitable for all three types of roasting.  All of these products are seeds which require a drying stage followed by a roasting stage. The main differences in roasting relate to time and temperature requirements.

Coffee roasting, for the sort of roasts I intend to do, hits a maximum bean temperature of around 450F and the duration is somewhere in the range of 10 to 20 minutes. For cacao, the roaster would need to operate in the 200F to 300F range for 15 min to 1 hour. The application for grain roasting that intrigues me is drying/roasting malted barley used in the production of beer or distilled spirits. Colored malt is made by gradually heating the barley from 150F to 185F over a several hour period. Caramel or crystal malts are produced by heating the barley on a ramp of 175F to 300F, creating additional color and flavor. Roasted malts are heated even higher, to as much as 450F. Nut roasting is in the range of 250F to 350F.

The roaster is first and foremost a coffee roaster. If the roaster can be built to be able to roast the other products WITHOUT sacrificing any aspect of roasting coffee perfectly, then it makes sense to do so.  My concerns are as follows:

  1. Residual material in the roaster that contaminates or flavors the coffee.
  2. Need to design orifices and clearances to work with the smallest seed (barley).
  3. Ability to clear any sort of blow-off such as chaff for coffee and the germinated sprout for malted barley.
  4. Residual material in the roaster that flavors the barley, cacao or nuts.
  5. Cost of additional components to make the roaster multi-use.

I’m planning on investigating these factors and may test them in a sample roaster. You will be the first to know the outcome!

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6 Responses
  1. David permalink
    February 24, 2010

    I am so relieved to find at least ONE person on the internet mildly interested in roasting coffee and barley in the same machine.

    Have you had any luck or found any information on this?

    I am roasting coffee using a air popper and looking for a bigger capacity- I am hoping that a drum roaster can do coffee and roast barley for my homebrews.

    Please email me if you’ve had any luck!

    • February 25, 2010

      Thanks, David. The roasting of seeds/nuts seems to have alot of commonality, just different time/temperature/heat input requirements. What got me thinking was our tour of Guinness Storehouse in Dublin. The tour included a section on malting and I was astounded to see machines very similar to coffee roasters. Probat, the world’s largest maker of coffee roasters, also makes, cocoa nib roasters, malt roasters, and nut roasters. Interesting. Good luck on trying. I would think a solid drum makes the most sense and you will need to make sure that any perforations for venting are sized small enough to prevent barley from passing through.

      • helen permalink
        January 19, 2011

        hi thank you for your efforts to gather information ,i was wondering what type roaster would you suggest i was intersted doing some roasting barley and some seeds for small business .thank you

        • Greg permalink
          March 21, 2011

          Helen did you get an answer for what roaster to use for seeds?

  2. Mark permalink
    September 29, 2011

    Dear Mr.Joe Johnston,

    I read your article and have the same question that Mrs.Helen asked.
    I am lookin for mini roast machine or produciton line for roasting barley and wheat around
    100 pounds per batch.
    Maybe you can advice on companies that make this equipment for mini roast line.
    I went through many companies in USA and contact Czech republic nobody can help.
    Waiting for your response.
    Sincerely,

    Mark
    USA
    P.S.Please confirm receiving of this e-mail.

    • January 20, 2012

      May I suggest you contact Diedrich Mfg. They build roasters in Idaho and may be able to meet your needs.

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