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  • KKTO and Corretto - Differences?

    Hi all,

    Interested in the fundamental differences in the roasts produced by these roasters. I think the the KKTO looks great, and Ive used a Corretto for over a year with fantastic results. Im now curious about any possible advantages the KKTO might have...

    Im interested in:

    - Batch size: 2000W HG seems to reliably roast 800g green. KK - you reckon your new set up will do 700g+? What can others reliably roast? Is ~800g pushing it with a TO?

    - Gentle heat: when we pushed the limits of our corretto (1kg roasts), we tended to get tipping/scorching. Before that, 600g had been ok, but afterwards I wondered about whether the HG produced too harsh a heat. Has anyone tried roasting side-by-side with these two roasters? Gra? I know you have both...

    - Airflow: having never seen a TO in action, how strong is the fan? Is there less airflow than with a HG? Linked to this question... has anyone compared moisture loss between the two styles of roaster? I tend to think that the corretto produces quite a dry roasted bean (not necessarily a bad thing?) compared to, say, a drum roaster.

    - In the cup: this part is entirely subjective, but Id be interested to hear anyones thoughts on the kind of roasts produced by each style of roaster and what beans that style might suit. Comparisons to drum roasters would also be welcome!

    Im currently living in Bulgaria without access to any roaster (let alone green beans) so this is an entirely academic exercise at the moment! But when we come home next year at least Ill know what might be worth pursuing...

    Cheers
    Stuart.

  • #2
    Re: KKTO and Corretto - Differences?

    Originally posted by 3136372330362530232C36420 link=1251522989/0#0 date=1251522989
    Interested in the fundamental differences in the roasts produced by these roasters. I think the the KKTO looks great, and Ive used a Corretto for over a year with fantastic results. Im now curious about any possible advantages the KKTO might have...
    The differences are in basic design equivalent
    The Corretto is similar a hot air roaster
    The KKTO is similar to a drum roaster

    In addition with the TO is-
    One piece of equipment,Chaff collection and small footprint that can be a stand alone unit or built in

    Originally posted by 3136372330362530232C36420 link=1251522989/0#0 date=1251522989
    Im interested in:

    - Batch size: 2000W HG seems to reliably roast 800g green. KK - you reckon your new set up will do 700g+? What can others reliably roast? Is ~800g pushing it with a TO?
    The KKTO is 1200W and although I have roasted 700gr batches and a test 800gr batch it all boils down to the heat chamber volume as to what size batch one can roast
    My particular roaster is optimised for 650/700gr

    Now thats pretty good for a 1200W power source

    Originally posted by 3136372330362530232C36420 link=1251522989/0#0 date=1251522989
    Gentle heat: when we pushed the limits of our corretto (1kg roasts), we tended to get tipping/scorching. Before that, 600g had been ok, but afterwards I wondered about whether the HG produced too harsh a heat. Has anyone tried roasting side-by-side with these two roasters? Gra? I know you have both...
    The KKTO can equalize the beans pre roasting by placing them in as normal and agitating at a low temp under 50deg C
    This will equalise the whole bean temp & moisture level, resulting in a very even roast

    Originally posted by 3136372330362530232C36420 link=1251522989/0#0 date=1251522989
    Airflow: having never seen a TO in action, how strong is the fan? Is there less airflow than with a HG? Linked to this question... has anyone compared moisture loss between the two styles of roaster? I tend to think that the corretto produces quite a dry roasted bean (not necessarily a bad thing?) compared to, say, a drum roaster.
    The air that is forced from the TO fan is very gentle compared to a HG and works in a whirlpool motion
    As mentioned above the TO design is more like a drum roaster

    Originally posted by 3136372330362530232C36420 link=1251522989/0#0 date=1251522989
    - In the cup: this part is entirely subjective, but Id be interested to hear anyones thoughts on the kind of roasts produced by each style of roaster and what beans that style might suit. Comparisons to drum roasters would also be welcome!
    Yes taste is subjective,
    I have roasted quite a few batches for other CS members so I will let them comment on this matter so you can get an impartial view

    Originally posted by 3136372330362530232C36420 link=1251522989/0#0 date=1251522989
    Im currently living in Bulgaria without access to any roaster (let alone green beans) so this is an entirely academic exercise at the moment! But when we come home next year at least Ill know what might be worth pursuing...
    They like the Greek/Turkish coffee in Bulgaria & they make the best sheeps milk feta cheese mmm

    KK

    Comment


    • #3
      Re: KKTO and Corretto - Differences?

      Thanks for the quick reply KK. Theres plenty of espresso here in BG - Turkish coffee whenever we visit the mahalle though!

      Originally posted by 5B7F767675754F5B7F637D7F100 link=1251522989/1#1 date=1251526163
      The Corretto is similar a hot air roaster
      Im not sure I agree with this point, actually. Corretto is very different in operation and flavour to fluid-bed roasters... anecdotally at least - I havent experimented with any fluid-bed roasters. As such, other might disagree with me on that point!

      Originally posted by 5B7F767675754F5B7F637D7F100 link=1251522989/1#1 date=1251526163
      The KKTO is similar to a drum roaster
      For me, having a home roaster similar to a drum roaster is the holy grail. I want the performance of a 1-2kg Probat for the price of a Corretto/KKTO! (Bit too much to ask?)

      But Id never thought of the KKTO as being that similar to a drum roaster. Can you explain why, KK (or anyone)?


      Id be interested in some input from anyone with a drum roaster, too. I know Dennis has been happy to speak up in the past about the corretto - prompting several improvements to our design. Seen the KKTO in action, Den?

      Anyway - more discussion! (Hope I didnt kill my own thread, here :P)
      Cheers
      Stu.

      Comment


      • #4
        Re: KKTO and Corretto - Differences?

        Originally posted by 6364657162647762717E64100 link=1251522989/2#2 date=1251528183
        But Id never thought of the KKTO as being that similar to a drum roaster. Can you explain why, KK (or anyone)?
        Tecnicaly speaking the KKTO roasters closest description is

        Heat    = Convection with slight fan forced air
        Roast chamber  = Is closest to a Packed Bed roaster (without the forced air and the turning bowl)

        KK

        Comment


        • #5
          Re: KKTO and Corretto - Differences?

          Thanks for that, Kosi

          I just had a look at this article on conduction vs. convection vs. radiation.

          Its quite interesting in that it asserts that even in a drum roaster, 80% of the heat transfer is by convection. I had assumed that a lot more would have been conduction with that much hot metal around, but apparently not. [Any opinions on this article?]

          I would guess that well over 90% of heat transfer would be by convection in fluid bed roasters (I guess more than that except that the heat produced during the cracks is significant, and is classed as conduction).

          For corretto, my guess is that the percentage would be almost as high as fluid bed. I say that because we tried pre-heating our corretto a few times and it made next to no difference.

          For KKTO, convection would be lower but conduction would be too. However, I guess that thered be a lot more heat transfer by radiation - would you agree? Ive seen halogen/infra-red TOs out there - is that the usual design, or are they normally some sort of electric element?

          Then theres drum roasters like the Deidrich which use infra-red... is this their main form of heating? Im not sure.


          Not sure what conclusions to make from all that, except that I think youre right, KK - your TO design is probably much closer to a drum roaster when assessed by heat transfer methods!

          Cheers
          Stu.

          Comment


          • #6
            Re: KKTO and Corretto - Differences?

            That was a great read thanks for the Link
            I came away knowing more about roasting than 30 min ago

            Originally posted by 3A3D3C283B3D2E3B28273D490 link=1251522989/4#4 date=1251536179
            For KKTO, convection would be lower but conduction would be too. However, I guess that thered be a lot more heat transfer by radiation - would you agree? Ive seen halogen/infra-red TOs out there - is that the usual design, or are they normally some sort of electric element?
            Turbo ovens come in two or three different variants

            1) The one I use is a solid round oven element that is similar to or the same as an oven thats fitted with a fan forced feature

            2) The other design is a round glass tube that has a spring like wire element inside it

            3) I have heard of other units that have a combination of infra red & element heat

            All are fitted with a fan that draws air from outside over the element and onto what is being heated/roasted/cooked

            Some come with lights and others no light

            Originally posted by 3A3D3C283B3D2E3B28273D490 link=1251522989/4#4 date=1251536179
            For KKTO, convection would be lower but conduction would be too. However, I guess that thered be a lot more heat transfer by radiation - would you agree? Ive seen halogen/infra-red TOs out there - is that the usual design, or are they normally some sort of electric element?
            My design encompass many heat transfer points
            1) Direct heat to the beans
            2) Indirect heat
            3) Fan forced heat
            4) Endothermic reaction in the beans
            5) Deflected heat gets recirculated

            But none are wasted they just get reused

            Note the roast chamber is a perforated smaller chamber inside a larger outer chamber
            This allows for even heat distribution and heat to pass through and bounce back

            KK

            Comment


            • #7
              Re: KKTO and Corretto - Differences?

              Originally posted by 3235342033352633202F35410 link=1251522989/0#0 date=1251522989
              Has anyone tried roasting side-by-side with these two roasters? Gra? I know you have both...
              Hi stuartgrant

              I find that the TO has a more gentle and even heat distribution that is fare more easy to control then the corretto . I agree with KK on his his answers in the technical side as fare as tipping/scorching I have not had this happen with the TO as I have with the corretto.

              Since building my KKTO I have not used the corretto and every roast so far has been spot on.

              Re:roasting weight I can,t help there as I only roast 600gm as I use 250gm bags for storage..

              As far as moisture loss my TO chaff is moist and the corretto dry as one is left in side the the oven the other blow-en out but both have around 10% loss ..

              Cheers Gra..


              Comment


              • #8
                Re: KKTO and Corretto - Differences?

                Thanks, guys!

                KK - thanks for pointing out how your TO works. Ive seen a few of your videos but didnt notice the bright light that I saw in reebars video... Now I know. Considering reebars problem with getting the beans hot enough, Id have to assume that the halogen TOs are somewhat less efficient at heating the beans that the element ones.

                Out of interest, what percentage moisture loss do you normally get?


                Gra - thanks a lot for chipping in! I hoped you would cos I know you have both roasters.

                We have a Corretto which weve worked on a LOT and essentially nailed it (even if I say so myself). We dont get tipping any more. On 800g roasts we lose 17% of the original weight on average. Excellent results in the cup, too - though to be fair we havent done really intensive cupping for roasting faults.

                I suppose Im wondering what kind of advantages the KKTO might have over a Corretto thats functioning well. My hunch is that youd get a more even (and maybe tastier?) roast with a gentler heat and lower moisture loss.

                What do people think about this?
                Cheers
                Stuart.

                Comment


                • #9
                  Re: KKTO and Corretto - Differences?

                  Originally posted by 2A2D2C382B2D3E2B38372D590 link=1251522989/7#7 date=1251552403
                  Out of interest, what percentage moisture loss do you normally get?
                  My results depending on what region the bean came from and what level of roast
                  Percentage moisture loss on average 12-15 %

                  I have noticed that the bigger the batch size the lower the moisture loss ??
                  (The 800gr test roast was 11.2%)

                  Originally posted by 2A2D2C382B2D3E2B38372D590 link=1251522989/7#7 date=1251552403
                  I suppose Im wondering what kind of advantages the KKTO might have over a Corretto thats functioning well. My hunch is that youd get a more even (and maybe tastier?) roast with a gentler heat and lower moisture loss.
                  The TO Roaster can be tweaked
                  It is small and can be stored away
                  It catches the chaff that the roast produces so its clean
                  It can also be used with a heat gun as its primary heat source with a small mod

                  KK

                  Comment


                  • #10
                    Re: KKTO and Corretto - Differences?

                    Originally posted by 7D5950505353697D59455B59360 link=1251522989/8#8 date=1251604726
                    The TO Roaster can be tweaked
                    It is small and can be stored away
                    It catches the chaff that the roast produces so its clean
                    It can also be used with a heat gun as its primary heat source with a small mod
                    All of the above plus you can still roast in the garage when it,s raining

                    And yes to finding that my roasts are sweeter in the cup...

                    Cheers Gra..

                    Comment


                    • #11
                      Re: KKTO and Corretto - Differences?

                      Thanks, legends! More good info.

                      Very interesting to hear that you get that low a percentage of moisture loss, KK. I have suspicions that 17% is too high...

                      Here in Bulgaria Id been sourcing roasted beans locally (of dubious freshness) until a good friend and CSer posted over some beans roasted in our shared Corretto. Immediately I noticed that the Corretto-roasted beans were quite dry and almost crumbled in the grinder. They taste amazing! But I wonder what affect this drying out has on flavour and longevity?

                      As for the advantages you list, KK and Gra (just playing devils advocate here!): our Corretto is fully tweakable, has a chaff collector and is used inside (in the garage) - so those arent advantages over our particular system. KKTO is nice and small, that is true.

                      But Im very interested in getting a KKTO set up (mid next year when we come home!) to look further into these differences in the cup!

                      Cheers
                      Stuart.

                      ps. Ive put together a document looking at the differences in heat transfer method and other dynamics between Corretto and KKTO roasters. Ill share what Ive come up with shortly.

                      Comment


                      • #12
                        Re: KKTO and Corretto - Differences?

                        Hi all -

                        Ive been nutting out heat transfer methods. Ive had to make a lot of it up based on my observations/assumptions, so tell me what you think:

                        Drum roaster:
                        - 80% convective heat transfer, significant conductive;
                        - excellent physical agitation;
                        - moderate air flow;
                        - small temperature differential, but large thermal mass (air and metal).

                        Fluid bed:
                        - probably 95% convective;
                        - very high air flow/agitation;
                        - high temp differential, but mitigated by air flow.

                        Corretto:
                        - probably 90% convective - sundry conductive/radiated;
                        - high air flow, moderate agitation rate;
                        - high temp differential, required because a lot of heat is lost;
                        - heat is quite concentrated (can be problematic).

                        KKTO:
                        - Id assume the proportion of convective heat transfer to be somewhere between drum and Corretto, with significant radiated heat transfer too;
                        - moderate air flow, moderate agitation;
                        - mod. to high temp differential.


                        Conclusions:
                        - best way to improve Corretto would be to increase the efficiency of heat transfer so you could turn the heat down. This could be done by: i) adding another (conductive or radiated) heat source (eg. BM element or a halogen lamp?), ii) keeping more heat in (eg. by insulating, by using a lid, by piping the air in from underneath, or by cutting slots in the BM pan to allow heat to penetrate the body a bit more).
                        - best way to improve KKTO would be to increase efficiency of agitation (eg. by adding more paddles onto stirrer, by using a smaller vessel for stirring in, by using a faster motor). Having never used or seen a KKTO, Im not the best person to suggest where it might fall down (tho maybe it doesnt, of course!).
                        - if one were designing a new kind of roaster, I think youd want to keep the proportion of heat transfer that is convective LOWER which you could achieve by having some other heat source (conductive or radiated). Im liking the idea of having using halogen lamps as additional heat sources. I think having an enclosed system like the KKTO greatly improves efficiency and explains why a 1400W TO can roast as much as a 2000W HG.

                        What do people think of this? I tried to be accurate in my comparisons and assumptions, but it could be plain wrong. Seems to fit though.

                        For the record, I still love Corretto! I think all of its "problems" listed above are tweakable. In general, I think the KKTO seems to be a better concept. Based on the observations above, I wonder if theres another way entirely?

                        Cheers
                        Stuart.

                        Comment


                        • #13
                          Re: KKTO and Corretto - Differences?

                          Originally posted by 484F4E5A494F5C495A554F3B0 link=1251522989/11#11 date=1251621688
                          I think having an enclosed system like the KKTO greatly improves efficiency and explains why a 1400W TO can roast as much as a 2000W HG

                          With the KKTO it all boils down to total volume
                          Reduce the volume & insulate to limit heat loss and you can increase the batch size and still get beautiful roast results  

                          Originally posted by 484F4E5A494F5C495A554F3B0 link=1251522989/11#11 date=1251621688
                          - best way to improve KKTO would be to increase efficiency of agitation (eg. by adding more paddles onto stirrer, by using a smaller vessel for stirring in, by using a faster motor). Having never used or seen a KKTO,

                          I have designed this roaster so far in about 15 different combinations some are not suitable  for a home build

                          The new kit model will have 68rpm at the paddle as opposed to 42rpm on the current roaster
                          Paddle design is also important for good agitation

                          Although not the same as the KKTO  you can have a look at CS member Farmroasts 1kg capacity TO build so you can see the possibilities this method of roasting has

                          It differs in two ways to the KKTO in that it does not have a suspended roast chamber & has 2 heat sources  with an element underneath

                          More homework for you
                          View it on the CS discussion thread

                          http://coffeesnobs.com.au/YaBB.pl?num=1185559848/17#17
                          And his Blog
                          http://coffee-roasting.blogspot.com/

                          Full build details
                          http://www.homeroasters.org/php/forum/viewthread.php?forum_id=52&thread_id=561

                          KK

                          Comment


                          • #14
                            Re: KKTO and Corretto - Differences?

                            Thanks again, KK - I feel like I should point out that youve done a fantastic job inventing your roaster and providing oodles of information for people wanting to build them! Many others would have gone straight to the patents office and tried to milk their idea for all the money they could! Good work.

                            Thanks too for the links to Farmroasts roaster. Its impressive... but, er, well beyond my ability to create! The reason the Corretto is so popular (apart from the fact that it does a good roast) is that its initially just a matter of putting two commonly available household items together. The biggest improvement to your design in that respect was the clever adaptation of the pasta set which seems so readily available now...


                            By the way, have you seen this YouTube video? Its a very neat looking job. Too large a bean vessel IMO... and Im not sure how effective the chaff catcher would be. Interesting though.


                            Lots of view of this thread - Id be keen to hear any other opinions on any of this?

                            Cheers
                            Stu.

                            Comment


                            • #15
                              Re: KKTO and Corretto - Differences?

                              Originally posted by 3D3A3B2F3C3A293C2F203A4E0 link=1251522989/13#13 date=1251718587
                              hanks again, KK - I feel like I should point out that youve done a fantastic job inventing your roaster and providing oodles of information for people wanting to build them! Many others would have gone straight to the patents office and tried to milk their idea for all the money they could! Good work.

                              Thanks Stuart
                              Some credit should go to my wife as she was the one that forced on me a strict design criteria to make a roaster or no roaster at all   :

                              But hey what would life be without sharing  

                              Originally posted by 3D3A3B2F3C3A293C2F203A4E0 link=1251522989/13#13 date=1251718587
                              By the way, have you seen this YouTube video? Its a very neat looking job. Too large a bean vessel IMO... and Im not sure how effective the chaff catcher would be. Interesting though.
                              I believe the roaster video link is for a home made version of the stir crazy base with TO heat source
                              The stir crazy gearbox is a little flimsy

                              Nice roaster though

                              KK

                              Comment

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