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Grind settings - do you need to grind finer for your home roasts?

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  • Grind settings - do you need to grind finer for your home roasts?

    Whilst the title might be confusing, I've noticed that when preparing a shot using my home roasts, I need to dial it in consistently finer than a commercial roast.
    I first noticed this when I bought the same beans, roasted and green, and my recipes were different: i.e. 8.7 grind setting on the commercially roasted, and 8.4 on my home roast

    I was recently reading over my little recipe notes, and noticed that my home roasts are all ground finer than the commercial ones.

    I was wondering if this is something that's common? Am I doing anything wrong/that can be improved in my roasts? Do I maybe just need to wait longer for resting period, because I'm very undisciplined there haha

    I'm just curious if there's any science or logic behind it

  • #2
    Without doing analysis I’d suggest it’s solubility.
    most commercial roasters want the most solubility from the beans which will transfer flavour to the cup and be more consistent from shot to shot.
    At least speciality roasters I know do.

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    • #3
      So many variables to consider here.

      My home roasts tend to be significantly lighter than commercial roasts, particularly as I like fruitier coffee and the lower depth usually brings this out. Even speciality roasters tend to cater for the masses who like 'strong' coffee (certainly not all roasters/roasts) which don't tend to need as fine grind.

      But in general I would agree my home roasts need a much finer grind than commercial roasts. Having said that never compared the exact same bean roasted at home vs shop bought. But you do need to consider age of beans, storage etc as part of the many variables!

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      • #4
        As above have mentioned. I've found that I generally grind finer with my home roasted That said, my current roast is grinding using almost exact same settings as the previous commercially roasted bean I put through the machine prior to it.

        Lots of factors to it.

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        • #5
          What do you roast on? What does your local roaster use by comparison? Of course they are going to be different. It’s not good or bad it just is. Are you happy with both?

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          • wirecutter23
            wirecutter23 commented
            Editing a comment
            I think type of bean mainly. I also experience a finer grind with home-roasted beans.

          • Barry O'Speedwagon
            Barry O'Speedwagon commented
            Editing a comment
            Lighter roasts will typically require a finer grind (as per post #3 above), and development time seems to also play a role (at least in my experiments).

            Longer resting periods will usually mean that you need to grind (slightly) finer.

          • Ted2013
            Ted2013 commented
            Editing a comment
            Barry I agree. I find that I have to gradually adjust finer with my home roasts and I do not start until 7 days after roast.

        • #6
          Hmmm.. that is rather interesting... I have found that too! I'm guessing it's how the beans are roasted (or what platform they are roasted on) that has some impact here...

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          • #7
            Another factor is roast duration. Typically roasting at home gives way to longer roast durations (especially when normalised for batch size) allowing more time for the beans cell structure to be dismantled

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            • #8
              I have had the same thing with both a behmor and a KL nano. I'll wait to see if the Bullet is any different...

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              • #9
                Originally posted by wirecutter23 View Post
                Another factor is roast duration. Typically roasting at home gives way to longer roast durations
                Interesting observation. Roast duration compared to what?

                GrahamK

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                • wirecutter23
                  wirecutter23 commented
                  Editing a comment
                  It’s my observation that a few commercial roasteries that I know of typically roast a few kilos batch size in around 10-15mins. Normalising for batch size and you get much quicker roasts compared to at home where you usually roast 300-500g in 20mins

              • #10
                Firstly important to differentiate between " home roasters". Some are people using commercial / semi commercial machines capable of achieving and maintaining appropriate environment temps for roasting coffee.

                Generally speaking with home roasting needing finer grinds, its more to do with less "overall" developed roasts / much longer times at lower environment temps. The mass of beans (in a low temp / low mass environment) is slowly taken to an end temp (often from a cold start) which creates ones preferred desired brown flavours.

                Compared to starting with a well pre heated large mass (drum) inside an oven where the environment temp (oven temp) is a steady 250C and it has the ability to quickly recover lost heat when a heap of cold hard green seeds are dropped into it, bringing the seeds up to much higher temps a lot quicker. Generally one ends up with a more soluble end product requiring a coarser grind to get a good extraction.

                As wirecutter23 mentioned about relative roast times, 300g of green in the same kind of roasting environment temperature which produced the commercial result in around 10 to 12 mins, should probably be done in around 6 - 8 mins.

                These different methods generate different flavour, creating large differences in flavour outcomes and depending on what one is after / frame of reference will determine whether one is more desirable over the other. Roasts taken to 2nd crack and beyond not so much.

                One mans undrinkable baked is another's ambrosia...








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                • #11
                  Thanks all
                  Looks like I have a bit of reading up to do on development time and solubility!

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                  • #12
                    Originally posted by Steve82 View Post
                    well pre heated large mass (drum) inside an oven ... bringing the seeds up to much higher temps a lot quicker.
                    I'm not sure this is the case. Drums have a longer time constant than spouted beds* which in turn are longer than fluidised beds. I have covered some of this previously here.

                    * A Corretto roaster approximates a spouted bed. I am assuming most home roasters use a Corretto or one of the commercial mini drum arrangements.

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                    • #13
                      Loving this thread. Thanks to all.

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                      • #14
                        Originally posted by Lyrebird View Post
                        I'm not sure this is the case. Drums have a longer time constant than spouted beds* which in turn are longer than fluidised beds. I have covered some of this previously here.

                        * A Corretto roaster approximates a spouted bed. I am assuming most home roasters use a Corretto or one of the commercial mini drum arrangements.
                        Yes ive read your hypothesis thanks, im not going claim I understand all of it.

                        Ive found the "old school" discussions around coffee roasting Environment Temps (oven temp) to be the most useful in producing well developed / minimum defect coffee.

                        In practice ive roasted many 1000s (over 10K) batches of coffee using popcorn machine, coretto, various small drums and KL air roaster (pimped popper).

                        My insulated / well pre heated (250C) solid SS gas fired drum (400g rated) with a 250g batch can roast properly developed / not baked / not scorched in 7.5 to 9 mins by treating it more like an oven but i have direct control over thermostat. The drum spins at 65 rpm and the seeds spend more time falling through the air.

                        I dont think 15 to 20 min coretto roasts are in any way close to a properly setup commercial spouted bed, this is pretty easy to pick in a blind cupping.
                        If you want to try a great fluid bed roast, where the engineer that designed the roaster actually roasts the coffee try getting hold of some Mountain Air coffee from USA, hot air roasting done really well.

                        In the end its just cooking, like any other seed / vegetable. Starting with a cold oven Vs hot one does different things and sous vide is different again. One only has to have experimented with different ways of cooking sweet potato to get this.

                        Im just a half arsed cook / coffee roaster with tonnes of experimentation under my belt, I will leave complex physics to those better qualified to discuss.






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