Results 1 to 9 of 9

Thread: Oil on beans days after roasting

  1. #1
    Senior Member
    Join Date
    Jun 2008
    Posts
    251

    Oil on beans days after roasting

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Beginner question here... I have noticed that some of the beans I have roasted (i.e. Mexican roasted 7 days ago to CS 9) start getting oily in bag with one-way valve. Dry and dark brown after roasting but now quite shiny. How come? Is this OK? Normal? Thanks. *:)

  2. #2
    Senior Member fatboy_1999's Avatar
    Join Date
    Jul 2004
    Location
    Melbourne
    Posts
    2,125

    Re: Oil on beans days after roasting

    Quite normal.
    Beans continue to degas and go through some changes for quite some time after roasting.
    A lighter roast will produce less oil over time. A darker roast, more.
    If the roast is initially a dark one, some oil will be present immediately.

  3. #3
    Senior Member
    Join Date
    Nov 2006
    Posts
    1,077

    Re: Oil on beans days after roasting

    Hi there
    Sounds OK to me,
    I generally get this about 5 - 7 days out, i roast to just on or just past SC generally.

    Mal


  4. #4
    Sleep is overrated Thundergod's Avatar
    Join Date
    Jul 2006
    Location
    Sydney
    Posts
    10,496

    Re: Oil on beans days after roasting

    Another reason why I line my valved bags with cheap freezer bags.
    I can toss out the oily freezer bag and leave the valved bag to air for a while and then be reused.

    The freezer bags cost less than $0.01c each and I can then use the more expensive valved bags several times (depending on how many times they are heat sealed).

  5. #5
    CoffeeSnobs Owner Andy's Avatar
    Join Date
    Mar 2004
    Location
    Internet
    Posts
    16,845
    Blog Entries
    1

    Re: Oil on beans days after roasting


    Its normal and as mentioned... good.

    Mostly... the amount of oil and when it appears is directly propotional to the roast depth.

    If you leave beans out in the air long enough the oils will evaporate (the oil is oxygen soluable from memory).... they will also stale for the same reason as those same oils evaporate entirely from the bean.

    Well stored beans that are just starting to show some oil spotting are often at their peak.

    As always, take lots of notes on your roasting to cup processes and you will find where you like them the best.

    ;)

  6. #6
    Senior Member
    Join Date
    Feb 2008
    Posts
    1,339

    Re: Oil on beans days after roasting

    Quote Originally Posted by Andy Freeman link=1228729208/0#4 date=1228738589

    Mostly... the amount of oil and when it appears is directly propotional to the roast depth.
    Maybe Im just regurgitating something Ive read somewhere but my feelings toward this are as follows.

    We know that the cell walls in coffee are elastic during FC, then become brittle on their journey to second crack, and that oils, gasses, etc. are trapped within the cells. Osmosis draws these oils to the bean surface.

    So, one theory might be that if too much heat is applied too quickly between FC and second crack the cell walls will become more damaged than if heat were applied ina more moderate fashion. This would explain why the oils may migrate to the bean surface quicker than if the heat had been increased slowly.

    Having tried varying the roasting times anywhere between 16 to 20 minutes Ive found that as opposed to the slower roasts, the quicker roasts present surface oils earlier, and the window when the beans are at their best is also reduced. I also feel that the 16min roasts are sharper, and more intense in flavour, while the roasts approaching 20min can be softer, yet well-rounded.

    I dont mean to say that one method is better than the other. I do believe they each have their place to help us achieve what we are looking for...

  7. #7
    CoffeeSnobs Owner Andy's Avatar
    Join Date
    Mar 2004
    Location
    Internet
    Posts
    16,845
    Blog Entries
    1

    Re: Oil on beans days after roasting


    For sure, I agree. The reference to roast depth was assuming that the same heat application profile was followed.

    Of course the other point is that one mans "softer, well rounded" is anothers "flat, dull".

    Ahhh... tis a magic little bean!

    :)

  8. #8
    Senior Member
    Join Date
    Jun 2008
    Posts
    251

    Re: Oil on beans days after roasting

    The batch in question achieved FC at approx. 9:45, then second crack at 15:30 - ejected immediately (CS 9.5ish). Yesterday was actually day 10 post roast, not day 7. From memory I started seeing signs of oil on the beans after about 5 days. Now theyre very shiny (and the bag is almost empty *;D).

    Although I was able to stretch out the time a bit between FC and second crack (almost 6 minutes), it was quite a quick roast. Ill raise the heat gun a little on the next roast with these beans (still have 2kgs left) to attempt to slow things down by a couple of minutes and compare what happens after they are bagged. I will try to roast them to the same level.

    Flavour wise I really enjoyed them! *One of the best so far :)

  9. #9
    CoffeeSnobs Owner Andy's Avatar
    Join Date
    Mar 2004
    Location
    Internet
    Posts
    16,845
    Blog Entries
    1

    Re: Oil on beans days after roasting

    Behmor Coffee Roaster

    Dont get too caught up in comparing the roast times... a heavy drum roaster and a heatgun have little in common. You will need to map your own roasting times and results.

    Take lots of notes, change one variable each time and see what works best for your setup.




Similar Threads

  1. Freshly roasted beans taste better "in a few days"?
    By lilmeh in forum General Coffee Related...
    Replies: 6
    Last Post: 11th October 2010, 11:56 PM
  2. What happened to my beans? Over two days, oily sheen, impossible to dose.
    By ezralimm in forum General Coffee Related...
    Replies: 3
    Last Post: 4th April 2010, 01:39 PM
  3. How Many Days Do You Keep Beans In The Grinder?
    By ezralimm in forum Roasted Bean Storage
    Replies: 55
    Last Post: 23rd July 2008, 09:52 PM
  4. Oils appearing after 1-2 days after roasting
    By thomm0 in forum Home Roasting - Tips, Tricks, Ideas
    Replies: 8
    Last Post: 23rd June 2008, 06:20 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •