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Corretto Batch Size - Heat Input Adjustments?

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  • #16
    Originally posted by marcism View Post
    Gotta say DBC, I've been following your posts closely and am keen to replicate your technique and set up. Keep up the good work and I'll definitely be shooting you a PM soon.
    BTW Happy to help out if I can - PM when ready :-)

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    • #17
      Well, here's an update. Just did a 700g roast last night, ambient - spannery! (around 3-4°).

      I've re-drilled the probe location in the pan about 20mm higher, which seems to have sorted the issue of the mis-reading probe (2C came at 225° which is pretty normal, rather than the 217 of last batch).

      Also been playing with the input settings which brought back the roast length a few minutes - still have some tweaking to do though in this area.
      The area requiring most work IMHO is the 1c-2c ramp, in slowing the roast - didn't drop it enough last night. The new probe location might help with doing this better - the first roast I did was all over the place, as when I dropped the temp and it seemed to stall - but could just be the probe reading right at the bottom of the bean mass so 'amplifying' (or de-amplifying!) the effect.

      One of the quirky things with the larger batch size is the definition of 1C. Normally I get first snap at 200° then into rolling 1C almost straight away and onto 210° - set your watch kinda thing. Last night - 1st snap about 190° - 1C started for real about 200° and rolled till 215° maybe? This is probably due the beans being hotter right under the gun than down the bottom of a bean mass. Not a huge issue - but just harder to log, as all the stages are slightly less defined.

      But will look forward to tasting the results in the cup… Here are the two past 700g profiles for comparison.

      Cheers!

      Matt


      BTW ran a "Coffee Appreciation" seminar over the weekend at a blokes church weekend away. Took the roaster and Diadema, did a batch with for about 15 fellas. Great fun! Lots of laughing (mainly at me!) but I think they all enjoyed the hilarious DIY nature of the process - then got to savour the results!

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      • #18
        This is interesting to see. I#m going to be looking for something around this batch size as well so keep on ironing out those kinks for me! :P Is your BM a big loaf type or the single paddle square type?

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        • #19
          Hi Marcism
          Mines the medium size single paddle rectangular type - there are some pics in my profile album, if you wanted a look at the setup.
          It's been an interesting process - from what I've seen the results in the cup so far are much deeper & more cocoa-like with the larger batch sizes - while the same beans in the smaller batch sizes get more fruit or florals? I'm thinking that in some ways it amplified the results I achieved when I covered/insulated the pan - so the greater thermal mass gives a deeper roast, and the reduced air-flow also impacts I'm sure…
          More tk!

          Matt

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          • #20
            Hi Matt,
            I soon got sick of the small roasts due to genetic laziness (not my fault, I blame the old man). I roast 630g in the same size set up as you and I agree with the comment about deeper choc flavour in the cup. My pan is not insulated and I start the roast @ 300 deg on the gun and start increasing at 10 deg increments when it stabilises at around 14 deg per minute up to about 500 deg on the heat gun to get it to 1st crack. I have the thermocouple fairly high in the pan and usually reach 1st crack between 195-200. That's where the difference comes in between the small and large roasts. Ramping down to achieve 3-4 deg rise to 2nd. It was much easier to control on the smaller roasts. From memory, I drop the heat gun 100 deg initially and then slowly reduce the temp to control the ramp. However, there are so many variables that come in to play that no two set-ups are the same.
            I've been roasting this way for over 2 years now and after trying various different profiles, I always seem to come back to this generic process. After all, the most important variable should never be overlooked and that is what you enjoy in your cup.
            The 630g roast yields about 520 in the bag and that lasts me a week (that's why the odd weight).
            It's good to hear about other people's journeys and tweaks. When the weather warms up my next project will be to pimp my corretto (the missus thinks I'm mad - she may be right but I think customising and spray painting a home made coffee roaster is perfectly reasonable).

            G.

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            • #21
              Hi G
              Thanks for your feedback! Sounds like we're getting similar results. I've always found the ramping to 1C works well too.
              Just a query - with the inputs you're using, how long does your roast stretch? The first one I did (which was a cracker in the cup) was around 22mins - I'm just not sure whether to try and pull it back to my more usual 17min smaller batch size profile - or just work with a longer roast expectation?

              Matt

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              • #22
                I usually reach 1st by 14 minutes and end at the first cracks of 2nd 5-6 minutes later so my profile is similar to yours. I have tried shortening and lengthening the time and many other variables but I keep coming back to this profile. I am roasting a 2 bean mix at the moment (equal parts Brazil pulped naturals and Peru ceja de selva) and the results definitely suit my taste buds.

                Just remembered, I'm out. Better go and crank up the Corretto!

                G.

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                • #23
                  Today's Roast

                  Here is the roast I just did and the equipment and the result

                  G.
                  Attached Files

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                  • #24
                    Wow.
                    I'm amazed you can get a climb like that - with my 700g batch I was up to 600 on the gun at the end and still pushing to get 22mins!
                    I guess that's the ambient, humidity & altitude combined with batch size. Don't know if I'll be able to match my smaller size profile without scorching or tipping - so just keep playing till it works I guess :-)

                    Matt

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                    • #25
                      Well, just cracked into my latest 700g batch.
                      What has really surprised me is how a blend you thought you knew well can change characteristics sooo much just with the batch size! My latest MochaJava roast is sensational. Still a bit longer in the profile than I would have expected/desired for a smaller batch size - but in the cup is thick, rich chocolate - and with much more depth than I have achieved in the same blend in smaller batch sizes. Less defined, I suppose, but oodles of flavour.
                      If I was going to try hypothesising, I'd think these larger, slower batch roasts are ideal for the indo/africans where you want think rich & earthy, with maybe the smaller lighter, slightly faster roasts better for highlight beans with a bit of zing - such as the centrals.

                      Anyway, my thought for the day… :-)
                      Happy roasting!

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                      • #26
                        Interesting.
                        That latest 700g roast, while maintaining big choc in a FW, is a much brighter and more acidic doppio than the early longer one. No surprise really, being a steeper ramp and faster roast than the first, but at 21mins I would still from a flavour balance point of view be looking to stretch it back out a bit. So I might need to reset my roast length expectations (and my RM preferences - I'm running out of room on the profile!) to incorporate these larger roasts.
                        I'll be looking to head back towards 22mins with a slightly slower ramp to 2C…
                        A work in progress to be sure!

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                        • #27
                          It's interesting isn't it. I have been doing the same thing, keep stretching out my roasts more and more. I'm generally in the 21 to 22min as well. As you know plenty of acidity to go around. I'm thinking how much would I have to really stretch out the malliard zone and the time between first and second crack to have dominant baking flavours?

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                          • #28
                            Yeah - not sure I've ever really experienced baked roasts. Had plenty of burnt, bitter ones though!
                            I'm surprised that it seems to be much less about the final CS colour - and much more about how you got there! All of my roasts are dropped just on 2C - all CS8-9ish, but the difference in flavour is massive depending on the early ramp. You can go from bright & acidic to deep cocoa - in one bean - all with the same final drop temp/colour. Can't see why you'd need to go to CS11 unless you liked oily, ashy flavours!

                            Here's my latest 700g batch from last night. Might still slow 1C-2C down a bit, but I'm thinking this is getting close to where I'm aiming at… but the results in the cup will be the decider!

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                            Also trying a slower than normal 350g batch of El Sal Aida (part of my other SO experiment!) - so will see what that does too…


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                            Happy roasting!
                            Matt

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                            • #29
                              Hi all
                              Update on the 700g batch size technique adjustment process. Just done a beautiful (no, let's say spectacular!) KJM style blend in the bigger batch size. Got a much smoother profile. Still stretched out to around 23mins, but aroma just explodes off the grinder and smooth, sweet and flavoursome in the cup, both as a FW and doppio. Getting there!

                              The one main difference with this batch was I pre-warmed the pan to 200° on the DMM, then dumped in the greens. Just allowed me to still use the lower temps during the ramp while still reducing the overall time a minute or too. Come to think of it, my very first attempt was in a hot pan from an earlier roast - so makes sense. This is quite a similar profile to that first, scary attempt!

                              The following two profiles show the difference pre-warming make with this bigger batch size - the first is the current great KJM batch with pan pre-warmed to 200° then green dumped in, then the second is a later Mocha Java Plus with only gentle prewarm (to 30°) which shows how much longer the roast took with the same ambient roast ramp technique…

                              More tk on this later roast…
                              Matt


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                              • #30
                                Update: The KJM batch is almost done - it's been brilliant! Lovely deep, rich cocoa both in a dopp and flat white today - fairly long rest, but well worth the wait!
                                I think the profile is around about right now for that batch size
                                We'll see how the MJ+ batch worked when I crack it tomorrow or the next day…
                                Matt

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