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Why are my Hottop roasts not degassing ???

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  • Why are my Hottop roasts not degassing ???

    Hello all,

    I wonder if anyone here could shed some light on a matter that has perplexed me for quite sometime now.

    When I used to buy freshly roasted coffee beans from a reputable roaster like Campos, the sealed coffee bags would look like a balloon after a few days with all the degassing taking place.

    For some reason I have never ever had this level of degassing with any of my home roasts on my Hottop, irrespective of roast depth or bean used, and I have been roasting for over three years now on my Hottop.

    I am always careful to immediately seal each batch I roast in one of the Coffee Snobs air tight seal bags for a few days until I am ready to use it.

    However, whether I store my roasted beans for a few days or a couple of weeks, I don't feel I am getting anywhere the level of degassing I observe in professionally roasted coffee beans.

    I wonder if anyone here is having a similar experience to mine or can offer a scientific explanation, or any explanation 🙂, as to why my Hottop roasts appear to produce very little degassing.

    Any feedback would be very welcome.

    Kind regards..

    Gaby 🙂

  • #2
    Solution 1. Your current batch of one way valves are working properly - ie you dont have a problem Test for this, put a roast into a normal sealed baggie, it will degasss but not escape

    Apart from missing the swelling balloon are the roasts satisfactory? taste good -?

    Comment


    • #3
      Professionally roasted and bagged coffee is also Heat Sealed, this ensures that the only place for gas to escape is the 1-Way Valve. The press-seal zipper closures used on bags are not always totally gas-tight...

      Mal.

      Comment


      • #4
        Thank you FNQ and Mal for your thoughts. I like your idea of using a zip bag with no valve to see if in fact I am getting degassing. I'll try that and see what I observe.

        To answer your question FNQ, I guess my roasts are like everyone else's, some I love the taste of and others I wonder why they taste average when their roast curves looked so perfect.

        I guess after three years I am still learning.

        Regarding the degassing issue, I was actually wondering if it may have something to do with the fact that the Hottop uses an electrical heating element rather than gas burner heaters in traditional roasters.

        In theory, gas burners consume the oxygen in the roasting chamber as they burn and you are effectively roasting in a CO2 rich roasting environment while with an electric heating element you would be roasting in an air environment that contained more oxygen and less CO2 relative to gas roasters.

        It led me to wonder whether coffee beans roasted in gas heated roasters were simply absorbing this excessive CO2 during the roast and then releasing it days later, hence more degassing, while coffee roasted in electrically heated roasters had less CO2 to absorb in the first place and hence less degassing afterwards.

        It's just a theory I guess.

        Are people getting healthy degassing when roasting on a Behmor roaster ??

        I wonder.. 🙂

        Comment


        • #5
          Originally posted by Gabster View Post

          In theory, gas burners consume the oxygen in the roasting chamber as they burn and you are effectively roasting in a CO2 rich roasting environment while with an electric heating element you would be roasting in an air environment that contained more oxygen and less CO2 relative to gas roasters.

          It led me to wonder whether coffee beans roasted in gas heated roasters were simply absorbing this excessive CO2 during the roast and then releasing it days later, hence more degassing, while coffee roasted in electrically heated roasters had less CO2 to absorb in the first place and hence less degassing afterwards.

          It's just a theory I guess.

          Are people getting healthy degassing when roasting on a Behmor roaster ??

          I wonder.. 🙂
          Good questions
          Wouldn't the burners consume the 02 under the roaster(ie the flame isn't in the chamber- we have indirect heating) and if so be replaced by the atmosphere?

          Comment


          • #6
            I am a novice roaster who uses a Hottop. Firstly I have bought roasted beans from local roasters that I am sure are pretty fresh in those bags with a one way valve and the bags do not swell up as you describe.

            Secondly I think my roasts in the Hottop (I have only done 4 so far) have or are degassing. I am currently putting them in one of those steel canisters with a one way valve in the lid and you get that strong roasted coffee smell in the room when the canister is stored. I have found it takes 5 -7 days for them to get to the point that I really like them. Think they probably still have more gas than bought roasts but I really like the coffee from this point.

            Not convinced by your theory about gas vs electric roasting because I understand there is a chemical reaction going on in the beans post roasting that is generating this CO2 but there are experts here who know a lot more than I about this.

            Comment


            • Gabster
              Gabster commented
              Editing a comment
              You are right Ted, the chemical reactions do produce CO2 but I was just at a loss as to why I am not seeing more degassing and started wondering if the heating method used was also a contributing factor. Some of the Campos coffee bags I have bought are like balloons and I never get anywhere near that level of degassing so I was wondering, being a curious kind a guy.
              Thanks for your feedback though and happy to see another Hottop roaster here..

          • #7
            Hmmmm, I didn't know the heating is indirect, in which case you are spot on, the environment in the roasting chamber would be normal atmosphere and I am back to square one.

            I'll try the zip bags with no one way valve and see if I spot a difference.

            Comment


            • #8
              It’s probably a combination of two things: 1. The CS ziplock bags you’re using are actually allowing for a little bit of transfer of trapped gases. 2. The coffee you roast at home is less developed so degasses slower.

              Comment


              • #9
                Hey Gabster, I roast in a Behmor but experience the same; my CS bags don't balloon up, which as mentioned before hopefully means they're working. And I make sure they are shut tight at the ziplock. But I have experienced what you say, I've bought roasted beans and the bag has been a balloon that you can squeeze out the gases from. I do also wonder what goes on here...

                Comment


                • #10
                  I wouldn't worry about it too much, so long as the end result in the cup is good...
                  It's an academic issue otherwise.

                  Mal.

                  Comment


                  • Gabster
                    Gabster commented
                    Editing a comment
                    God bless you Mal and thanks for your feedback. I guess the point that LeroyC raised is an important question for me; are my roasts under developed??

                    I have often wondered about this myself and would love to exchange notes with some here on how to meaningfully compare how I am roasting certain beans with how they should be roasted for adequate development.

                    One challenge has always been how to meaningfully compare roast data from different machines with different probe placements and measurement characteristics.

                    I have been thinking about this and one way around it, I believe, would be to use the FC temperature as a point of reference to standardise around since FC happens more or less around the same point/temp for most beans and irrespective of machine used. (more or less)

                    FOR EXAMPLE:-

                    Say FC for most beans happens between, say, 180 to 182 degC. on a specific roaster

                    Knowing this we can express the temp we preheat the roaster before dropping the beans in for a roast relative to this typical FC temp. Eg we could then say we preheat the roaster to the same temp as FC or, 10 degC less or more than the FC temp etc etc before dropping the beans to start a roast

                    Also we can express the final temp of the roast in the same way, EG 10 degC or 15degC above the FC temp etc etc.

                    This, together with the total time of the roast, and the development time from the point of FC to end of roast, should help us compare roasts between each other and exchange meaningful notes on how to get the most from certain beans etc.

                    I digress perhaps but I am very thirsty for meaningful tips on how to get the best from certain beans in terms of what temp I should preheat the roaster to before dropping the beans in; what temp I should aim to end the roast at; what development time ratio I should aim at etc etc.

                    I would love to be able to compare notes and learn from the more experienced roasters here, especially Andy of course..

                    Thanks again Mal and everyone for your valued feedback..

                • #11
                  For a larger scale commercial roaster I'd be interested to know how long the roasting process goes for compared to say a Behmor. Could it have something to do with longer roasts drying the beans out and drier beans not outgassing as much? I have recently noticed that the beans I roasted in my Behmor needed a measurably finer grind than some Lavazza Gran Crema beans I was given to try out. I didn't notice my own roast swelling the bean bags either. At any rate what I just said there goes against the grain of the adage "older beans need a finer grind". It might be a mistake on my part to try and find a relationship between possibly unrelated things though - eg, outgassing, freshness, moisture content and grind size....
                  Last edited by YeastNCaffeine; 21 September 2020, 12:49 PM.

                  Comment


                  • #12
                    Having a crack at the initial question...

                    CoffeeSnobs valve bags are the best available storage for coffee. They are 3 layers to provide different functions.
                    1. inside is PET, food safe for food contact (eg: coke bottles).
                    2. middle layer is aluminium foil, a thin but solid barrier from air in both directions
                    3. Outside is PP, strong and flexible to hold it all together.
                    4. The valve is one-way, to let gasses out and not in.
                    The bag will only perform 100% of those functions when it is heat sealed. The biggest reason you don't see the bags blow-up is the zip seal is not a pressure seal and air can push out past it easier than expanding the stiff bag. It won't allow any air in to it though as the internal pressure will be slightly higher than the room pressure outside.

                    If you heat sealed, the bags would expand up to the pressure release value of the valve and if you taped over the valve they would go round like a footy.

                    At the Snobbery, we'll occasionally get orders of 2.5kg ground coffee (a pet hate of mine) and the ground coffee can block the valve. A Sunday roast, grind, seal will be rolling around on the packing table Monday morning and bloody hard to get into a satchel for freight. It takes a fair amount of weight (near uncomfortable amount) on the bag to release the first of the gasses but once started we can reduce the bag size to small enough to pack.

                    If you want to experiment - seal one of the Snobs bags with some brown paper over the end and press with a hot iron (try not to heat the zip seal though), put a bit of tape over the holes in the valve and it should expand in the first couple of days.

                    Originally posted by Dimal View Post
                    I wouldn't worry about it too much, so long as the end result in the cup is good...
                    It's an academic issue otherwise.
                    Spot-on Mal.

                    Don't get hung-up if your coffee is degassing instead get hung-up on the taste of it compared to your previous roasts of the same bean.
                    Keep LOTS OF NOTES to improve your outcome.

                    Taste is the best way to determine if something is under developed...
                    Does it taste like hay or peas or sour? - prob under developed, adjust your roasting to suit, slow it down, lengthen it out or finish later.


                    One challenge has always been how to meaningfully compare roast data from different machines with different probe placements and measurement characteristics.
                    Meaningful comparison? Won't be done. You can get rough idea by looking at the roast curve but copying it, even on the same roaster can yield different results with data not shown (like ambient room temperature and amount of induced air). ie: on your Hottop the cleanliness of your filter will cause the same profile to give different results.

                    Meaningful = First Crack 196C

                    First Crack (not the TLA of FC = Football Club) is at 196C on an Arabica beans at sea level (all of Australia is at sea level really). Your probe placement, accuracy, lag will vary between setups so the only meaningful point in a roast is where first crack happened.

                    Each users setup will know where their own first crack happens and they can extrapolate roughly from there but remember, not all probes are accurate in the 200C range and while your machine shows 182C first crack that 6C error might be 2C or 20C at an indicated 200C.

                    It is REALLY IMPORTANT to cut your own path, keep your own records and temperatures (which are accurate to you) as nothing really compares to anyone else's environment.

                    Comment


                    • #13
                      Wonderfully explained Andy...

                      Mal.

                      Comment


                      • #14
                        Thank you very much Andy for your time and your very detailed response, and thank you everyone for your feedback.

                        I fully agree, and I know, that we all have to cut our own path, and yet I find myself hungry and eager to compare notes and to learn from others how to continue to improve my game, and the taste in my cup. 🙂

                        I guess part of my challenge is the fact that I am a chemical engineer by education and my approach to everything is very specific and very measured (it drives my wife mad...) so, by nature, I find myself searching for "certainty" where ever possible, hence the nature of my questions above.

                        I actually record, measure and analyse every roast I do but I now feel I have hit the ceiling of my roasting skill level and need to somehow learn from those more skilled than myself.

                        From the responses I received here, I feel I am probably under developing my roasts in my eagerness to shorten roast times to capture the brighter, more floral/ fruity notes that I love and look for in my roasts, but that I rarely get if I am honest. 😞

                        Perhaps I should post a separate thread on the what are the best strategies one should adopt to avoid under development while also not destroying those brighter more floral/fruity notes.

                        For example, which of the following would be more effective in overcoming under development :-

                        1) Lengthen the drying phase of the roast
                        2) Lengthen the Mallard Reaction phase of the roast
                        3) Lengthen the time between FC and end of roast
                        4) Roast at a lower heat setting all together to allow the bean to roast more slowly and more fully
                        5) Should one aim for higher or lower end of roast temperature
                        6) Should one preheat the roaster to a higher or lower temperature before dropping the green beans to start the roast
                        7) Adopt a "Soak" stage at the start of the roast to allow the beans to warm up gently for a little while before hitting them with full heat
                        8) And finally, how does one ensure proper development while also not destroying those brighter floral notes

                        I am hoping to learn the tricks to better roasting before I develop high blood pressure and can't drink enough coffee in a day to experiment and find out for myself. 🤣

                        Thanks again Andy, and everyone, for your helpful and valued feedback.

                        Kind regards....Gaby

                        Comment


                        • #15
                          I roast with a Kaffelogic Nano 7 and found this as well. The 250g Campos beans I used to buy are pressurised due to de-gassing, but I've never observed any kind of meaningful de-gassing from my beans. I figured it was due to the difference in roasting with a commercial roaster vs home roaster.

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