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  • Small Bubbles in Crema

    Hi all,
    I am hoping that someone might be able to tell me what it means when there are small bubbles on the top of the crema instead of a smooth creamy texture? I happens every now and then, not all the time.

    I am using a compak K10 and Silvia, I home roast the beans.

    thanks
    rynnlic

  • #2
    Re: Small Bubbles in Crema

    Small bubbles form on the surface of your crema when the coffee is very fresh (usually 1 - 3 days after roast day). The bubbles are caused by co2 gas given off by recently roasted coffee. This is the same gas which causes your sealed coffee to baloon in a sealed bag, the first few days after roast.

    If you drink coffee too fresh (1 - 3 days after roast) it wont taste very nice. Some origins need longer to rest than others, but the general rule of thumb is to start drinking after 72 hrs from time of the roast and consume within 2 weeks or so. Some coffee tastes better after a week or more of rest... eg. some indian monsoon malabar.

    If you see a few small bubbles in the crema, thats pretty normal. If the surface is absolutely covered in bubbles, then it might need another day of rest.

    Comment


    • #3
      Re: Small Bubbles in Crema

      Originally posted by 706B74636E3A33020 link=1278138919/1#1 date=1278139816
      Small bubbles form on the surface of your crema when the coffee is very fresh
      Have not experienced this, perhaps Im not very observant.

      Originally posted by 706B74636E3A33020 link=1278138919/1#1 date=1278139816
      If you drink coffee too fresh (1 - 3 days after roast) it wont taste very nice.
      Thats a pretty sweeping statement Rival, I roasted some Yemen BI about an hour ago and just pulled a shot, what was it like? to my palate, great, same with Monsooned Malabar, I like it hot off the press, a few days old or a week old, sure it changes in character but its still very good.

      Im sure others will disagree, however I always have enjoyed shots from freshly roasted beans, no accounting for taste is there?

      Comment


      • #4
        Re: Small Bubbles in Crema

        The bubbles are quite probably (as stated) CO2 given off by fresh coffee.
        Whether the coffee tastes good to you is up to you. I like my coffee, depending on the bean and roast level, from 5 minutes to 5 weeks post-roast.

        Greg

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        • #5
          Re: Small Bubbles in Crema

          Thanks for your responses - I love the differing thoughts.

          Generally experience has shown me that I must not give in to temptation and drink too early after roasting. My usual is to drink after day 7 for some beans, but often day 9 - 14 for others.

          cheers

          Comment


          • #6
            Re: Small Bubbles in Crema

            Some people may actually like the degassing taste... most in the coffee community dont though. To each their own, there is no right or wrong.

            Large bubbles pouring out during extraction is another sign of coffee that might be too fresh. After 3 days generally the degassing phase is winding down, allowing the subtle flavour nuances to show through.

            Comment


            • #7
              Re: Small Bubbles in Crema

              Here is an excellent quote from barista mag which explains degassing:

              The roasting process triggers chemical reactions in the beans which go on to establish the development of flavor, aroma, body, crema, and other characteristics unique to the particular beans. These reactions are quite vigorous at first, and as we recall from our days of science at school, all chemical reactions give off byproducts. In the case of coffee, the byproduct is carbon dioxide or CO2.

              And since there is a great deal of activity immediately after roasting, coffee beans can be categorized as ‘alive’ or fresh. Ironically, though, coffee is too ‘alive’ in the immediate period after roasting, and therefore should not be used for a predetermined amount of time. Batches must undergo a period of rest prior to use. In order to mature, coffee must settle in a protective environment, much the same as red wine eases into its true and best character. And sadly, this is a fundamental flaw of many roasters and baristas. They lack the understanding that coffee that is too fresh is not ideal for use, particularly as espresso. Roasted coffee beans need time to settle somewhat, time to develop persistent crema, rounded body and complexity of flavor. In other words, they need time to get better.

              However, coffee beans will not undergo this maturation phase if they are exposed to air for an inconsiderate period of time before being packaged. Once out of the roasting machine, the longer it takes the beans to cool affects the ultimate life span of freshness in the roast. The longer the length of time it takes to encase the coffee beans in a protective environment, the shorter the period of freshness for the coffee. Of course, like red wine, the storage environment the packaged coffee is then put into also plays a part in extending or reducing this freshness window.

              “Protective environment” is in reference to appropriate packaging material. The point is to prevent the wonderful sugars and elements essential to the favorable makeup of the espresso from being oxidized. Exposure to our atmosphere and the air we breathe creates oxidization, and degrades the chemical structure of all the essential components necessary for the creation of a spectacular espresso.
              Also, dark roasts degas faster than light roasts, and 100-percent arabica beans degas with a lesser volume of CO2 than arabica/robusta mixes. Further, if the coffee beans are stored in a hot environment, they degas faster than when stored in a cool environment like that of a wine cellar. All these scenarios affect the rate of degassing, and therefore the shelflife, or freshness, of the coffee beans.

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              • #8
                Re: Small Bubbles in Crema

                Depending on beans and age I do get small bubbles toward the end of the pour on the lever machines as the pressure comes off toward the end of the pour but generally none during the early to mid stages of the pour.

                I would tend to agree with the extra CO2 being given off, it is also noticable when using fresh beans in a Syphon or Plunger as it manifests itself as fake Crema in a Plunger and extra bubbles in the Syphon while brewing.

                Comment


                • #9
                  Re: Small Bubbles in Crema

                  Could it also be from tamping too hard and over extracting? Ive noticed sometimes i get a few small bubbles form from the slower drip of an over extraction.

                  Comment


                  • #10
                    Re: Small Bubbles in Crema

                    Originally posted by 756E71666B3F36070 link=1278138919/5#5 date=1278152154
                    Some people may actually like the degassing taste... most in the coffee community dont though. To each their own, there is no right or wrong.

                    Large bubbles pouring out during extraction is another sign of coffee that might be too fresh. After 3 days generally the degassing phase is winding down, allowing the subtle flavour nuances to show through.
                    Well looks like I have to eat humble pie, roasted some of the Yemen BI 3 days ago and another batch today and just did a direct comparison, 3 do v 2 hour old, both shots were 15 grams of coffee, same grind setting and extraction time, the result was unequivocally in favour of the 3 day old, smoother, more chocolaty an all round better shot, I was wrong. :-[

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                    • #11
                      Re: Small Bubbles in Crema

                      Some beans just have more co2 than others as well. I find some beans still produce bubbles after 7 days.

                      Comment


                      • #12
                        Re: Small Bubbles in Crema

                        Originally posted by 0D31382035540 link=1278138919/9#9 date=1278402239
                        Well looks like I have to eat humble pie, roasted some of the Yemen BI 3 days ago and another batch today and just did a direct comparison, 3 do v 2 hour old, both shots were 15 grams of coffee, same grind setting and extraction time, the result was unequivocally in favour of the 3 day old, smoother, more chocolaty an all round better shot, I was wrong.  :-[
                        I roasted a batch of Yemen about a week ago and the bag wont be cracked for another day or so yet.... Love my Yemen at 7 or 8 days post roast onwards 8-)

                        Mal.

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