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Oil on beans (or lack thereof)

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  • Oil on beans (or lack thereof)

    What are people's thoughts on oily beans?
    As we walked past some shiny beans on display in a shop, my partner was saying she used to have to regularly clean the hopper at her work due to oil from the beans.
    My home-roasted beans are never oily or shiny.
    Is this good? Or bad? Or, like most things coffee, neither and both?

  • #2
    I think it's a sign of over-roasting... Definitely should not be oily immediately after roasting.
    If I take a roast as dark as possible, I weed out any shiny ones while they're cooling.
    If they're oily immediately after roasting I'd throw them, probably.

    However, we used to get a dark roast from North QLD roaster at work and they were always oily.
    At first I questioned how they'd let them out like that, however I've come to realise from experience that they often 'oil up' after a few weeks, if roasted dark enough.


    • #3
      Oil on beans is primarily related to 2 factors - depth of roast and age.
      A very dark roast will have oil right away.
      A dark roast will begin to develop oils on the surface within a few days and the older it gets, the more oil will present.
      A light roast might not develop much, if any, visible oil on the surface.

      As to good or bad, you have pretty much guessed the answer.
      It depends on the individual.
      Your partner makes a very good point about the cleaning of the hopper.
      The oilier the beans, the more residue gets left behind. You need to be sure to keep all parts of the grinder clean as you can end up with some particularly funky residue if left alone for too long.

      My home roast beans are usually pulled around the start of 2nd crack. Very little or no visible oil on day 1, but might start to show a little from the 5 day mark on.