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Results of my fermentation experiment

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  • matthewo_brien
    Hi Everyone, I thought I would post the results of a little experiment I have just finished running, as I know it will change what I do in future. Basically, I
    Message 1 of 8 , Oct 2, 2002
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      Hi Everyone,

      I thought I would post the results of a little experiment I have just
      finished running, as I know it will change what I do in future.

      Basically, I wanted to compare the effects of long v's short
      fermentation, and yeast settling in a standard sugar wash with
      standard turbo yeast. So I ran two ferments, both with 6kg sugar,
      packet of standard turbo (both bought from the same shop on the same
      day with the same batch number on the pack) and 25L of water. These
      were both setup at the same time, same water etc etc.

      They both went into a 25 degree constant temperature room, had the
      same starting SG, and were both stirred daily at the same time. (I'm
      sure you get the picture now that they are the same!).

      The first I took out after 7 days, when bubbling had basically
      finished with both. It was left 24 hours to settle, and then
      decanted into the still leaving the sediment behind.

      The second was taken out after 13 days, and then put into a 4 degree
      fridge for 24 hours to settle (the process I use for my flavoured
      washes), and then transferred to a second fermenter, leaving the
      settled muck behind. This was then let warm up to room temp for 24
      hours, and further settling occurred, and then transferred into the
      still, leaving the small amount of sediment behind.

      They were both distilled at the same rate and in the same way (but
      obviously a week apart!)

      The results - the yield was the same - but, the longer
      ferment/settled wash is obviously different (better) in smell and
      taste - much more "pure" ethanol, with hugely reduced harsh "acetone"
      type smells (but both are very good - this is in comparison!). I
      thought this was my preconceptions, so gave the samples of both (un-
      carboned) to friends to taste in blind comparison, and the longer
      ferment was chosen as better 100% of the time (sample size of 5).

      They have both been put on carbon, and I'll let you know how that
      goes.

      Hope this is interesting/helpful for some - I know how I will be
      doing my sugar washes from now on!

      Matt
    • Mike Nixon
      matthewo_brien wrote: Subject: [Distillers] Results of my fermentation experiment Hi Everyone, I thought I would post the results of a little experiment I have
      Message 2 of 8 , Oct 2, 2002
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        matthewo_brien wrote:
        Subject: [Distillers] Results of my fermentation experiment

        Hi Everyone,

        I thought I would post the results of a little experiment I have just
        finished running, as I know it will change what I do in future.

        Basically, I wanted to compare the effects of long v's short
        fermentation, and yeast settling in a standard sugar wash with
        standard turbo yeast.  So I ran two ferments, both with 6kg sugar,
        packet of standard turbo (both bought from the same shop on the same
        day with the same batch number on the pack) and 25L of water.  These
        were both setup at the same time, same water etc etc.

        They both went into a 25 degree constant temperature room, had the
        same starting SG, and were both stirred daily at the same time.  (I'm
        sure you get the picture now that they are the same!).

        The first I took out after 7 days, when bubbling had basically
        finished with both.  It was left 24 hours to settle, and then
        decanted into the still leaving the sediment behind.

        The second was taken out after 13 days, and then put into a 4 degree
        fridge for 24 hours to settle (the process I use for my flavoured
        washes), and then transferred to a second fermenter, leaving the
        settled muck behind.  This was then let warm up to room temp for 24
        hours, and further settling occurred, and then transferred into the
        still, leaving the small amount of sediment behind.

        They were both distilled at the same rate and in the same way (but
        obviously a week apart!)

        The results - the yield was the same - but, the longer
        ferment/settled wash is obviously different (better) in smell and
        taste - much more "pure" ethanol, with hugely reduced harsh "acetone"
        type smells (but both are very good - this is in comparison!).  I
        thought this was my preconceptions, so gave the samples of both (un-
        carboned) to friends to taste in blind comparison, and the longer
        ferment was chosen as better 100% of the time (sample size of 5).

        They have both been put on carbon, and I'll let you know how that
        goes.

        Hope this is interesting/helpful for some - I know how I will be
        doing my sugar washes from now on!

        Matt
        ============================
        Hi Matt,
         
        No doubt about it.  I think that everyone will agree that you've done a very thoughtful and well controlled experiment, and done just the right thing to get impartial judgement of the results.
         
        Beer brewers would be able to give you heaps of detail about what you have found, but essentially it is akin to short-term maturation.  The first batch that you distilled right away contained everything that the yeast produced in the main ferment, and that includes all the higher alcohols etc we associate with the tails, and esters like ethyl acetate that we see in the heads.  By leaving your second batch to ferment longer, a lot of these byproducts were changed to less unpleasant compounds, and by getting rid of most of the dead yeast by settling at low temperature (nice one!), you got rid of much of the other possible source of bad flavors, the contents of the yeast 'carcases'.
         
        If you have the patience to manage your ferments as well as you have done here, then you will certainly enjoy a much cleaner product.  A very nice bit of work Matt!  Many thanks for that.
         
        Mike N
         
      • matthewo_brien
        ... Mike, I m glad you find it helpful! I also wonder how much the aeration helps, which occurs during the transfer from one fermenter to the other. I set one
        Message 3 of 8 , Oct 2, 2002
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          > By leaving your second batch to ferment longer, a lot of these
          > byproducts were changed to less unpleasant compounds, and by
          > getting rid of most of the dead yeast by settling at low
          > temperature (nice one!), you got rid of much of the other possible
          > source of bad flavors, the contents of the yeast 'carcases'.

          Mike,

          I'm glad you find it helpful!

          I also wonder how much the aeration helps, which occurs during the
          transfer from one fermenter to the other. I set one fermenter up on
          a bench, and then the other below it with the top open, and then just
          open the valve at the bottom of the first. Obviously this aerates
          quite well as it splashes into the bottom fermenter.

          I would guess that this aeration could oxidise some compounds, and
          also increase surface area so lighter volatiles would evaporate. It
          may also kick start some further (if small amounts) of fermentation?

          Just some random thoughts I have been having!

          Matt
        • Michael
          Hmm, thanks for the info. It will come in use. As far as brewing goes, when your yeast starts off, it will break the sugar down with the use of any available
          Message 4 of 8 , Oct 2, 2002
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            Hmm, thanks for the info. It will come in use.

            As far as brewing goes, when your yeast starts off, it will break the
            sugar down with the use of any available oxygen. Yeast will produce
            methanol instead of ethanol at this stage. When the oxygen is used
            up, and there is a layer of carbon dioxide over the top of the
            liquid, the yeast will then start breaking the sugar down without
            oxygen and produce your ethanol. A lot of brewers go to large
            efforts to limit the amount of oxygen that is present at the start.
            Some even use CO2 cylinders to replace the air in their barrels
            before they seal it up for brewing. It is very common to take care
            not to aerate the water as the brew barrel is being filled.

            However, this applies to the beginning of brewing, not at the end.
            Beer brewers avoid aerating or treating the beer rough between
            brewing and bottling, since this will cause the beer to produce a
            poor head. However, this still does not apply to us...

            So in the end, I don't know either. But thanks for the info ;)

            Mike G

            --- In Distillers@y..., "matthewo_brien" <mobrien@u...> wrote:
            > Mike,
            >
            > I'm glad you find it helpful!
            >
            > I also wonder how much the aeration helps, which occurs during the
            > transfer from one fermenter to the other. I set one fermenter up
            on
            > a bench, and then the other below it with the top open, and then
            just
            > open the valve at the bottom of the first. Obviously this aerates
            > quite well as it splashes into the bottom fermenter.
            >
            > I would guess that this aeration could oxidise some compounds, and
            > also increase surface area so lighter volatiles would evaporate.
            It
            > may also kick start some further (if small amounts) of fermentation?
            >
            > Just some random thoughts I have been having!
            >
            > Matt
          • Michael
            ... -snip- and were both stirred daily at the same time. -snip- Arr! Oh no! Don t do that. You want the yeast to be forced into a secondary method of
            Message 5 of 8 , Oct 3, 2002
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              --- In Distillers@y..., "matthewo_brien" <mobrien@u...> wrote:
              -snip-
              and were both stirred daily at the same time.
              -snip-

              Arr! Oh no! Don't do that. You want the yeast to be forced into a
              secondary method of reproduction due to the lack of oxygen. This
              produces more ethanol and less byproducts.

              When the yeast starts reproducing, it quickly uses up the available
              oxygen, and forms a carbon dioxide layer over the surface of the
              liquid. Every time you open the barrel, and worse still stir it, you
              introduce more oxygen.

              Mike G
            • matthewo_brien
              Mike G, Oops - should have been more clear! By stir, I mean slosh around the fermenter - kind of rocking it around its rim getting circular motion going and
              Message 6 of 8 , Oct 3, 2002
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                Mike G,

                Oops - should have been more clear! By stir, I mean slosh around the
                fermenter - kind of rocking it around its rim getting circular motion
                going and the settled stuff mixes back into the column. The lid
                stays on!

                Matt


                --- In Distillers@y..., "Michael" <god@p...> wrote:
                > --- In Distillers@y..., "matthewo_brien" <mobrien@u...> wrote:
                > -snip-
                > and were both stirred daily at the same time.
                > -snip-
                >
                > Arr! Oh no! Don't do that. You want the yeast to be forced into
                a
                > secondary method of reproduction due to the lack of oxygen. This
                > produces more ethanol and less byproducts.
                >
                > When the yeast starts reproducing, it quickly uses up the available
                > oxygen, and forms a carbon dioxide layer over the surface of the
                > liquid. Every time you open the barrel, and worse still stir it,
                you
                > introduce more oxygen.
                >
                > Mike G
              • Zeke Jones
                The purpose of using an airlock is to starve the yeast of oxygen...If the wash is still fermenting,aereating (oxygenating) it will cause the yeast to
                Message 7 of 8 , Oct 3, 2002
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                  The purpose of using an  airlock is to 'starve' the yeast of oxygen...If the wash is still fermenting,aereating (oxygenating) it will cause the yeast to more-fully digest/break down the sugars,creating more acetic acid and less alcohol....this is why transfer between fermenters should be made by siphoning,not pouring.....

                  >
                  >I also wonder how much the aeration helps, which occurs during the
                  >transfer from one fermenter to the other. I set one fermenter up on
                  >a bench, and then the other below it with the top open, and then just
                  >open the valve at the bottom of the first. Obviously this aerates
                  >quite well as it splashes into the bottom fermenter.
                  >
                  >I would guess that this aeration could oxidise some compounds, and
                  >also increase surface area so lighter volatiles would evaporate. It
                  >may also kick start some further (if small amounts) of fermentation?
                  >
                  >Just some random thoughts I have been having!
                  >
                  >Matt
                  >
                  >
                  >
                  >


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                • Scott Rudy
                  I thought at the beginning oxygen was a good thing. the cavorting yeasties needed oxygen to reproduce then when deprived of oxygen they started to produce
                  Message 8 of 8 , Oct 3, 2002
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                    Re: [Distillers] Re: Results of my fermentation experiment I thought at the beginning oxygen was a good thing. the "cavorting yeasties" needed oxygen to reproduce then when deprived of oxygen they started to produce CO2 and alchohol. it was good to have oxygen at the begining so that you had lots of yeasties to do the work.

                    am i mistaken
                    scott

                    on 10/3/02 12:50 PM, Zeke Jones at joneszeke@... wrote:

                    The purpose of using an  airlock is to 'starve' the yeast of oxygen...If the wash is still fermenting,aereating (oxygenating) it will cause the yeast to more-fully digest/break down the sugars,creating more acetic acid and less alcohol....this is why transfer between fermenters should be made by siphoning,not pouring.....

                    >
                    >I also wonder how much the aeration helps, which occurs during the
                    >transfer from one fermenter to the other. I set one fermenter up on
                    >a bench, and then the other below it with the top open, and then just
                    >open the valve at the bottom of the first. Obviously this aerates
                    >quite well as it splashes into the bottom fermenter.
                    >
                    >I would guess that this aeration could oxidise some compounds, and
                    >also increase surface area so lighter volatiles would evaporate. It
                    >may also kick start some further (if small amounts) of fermentation?
                    >
                    >Just some random thoughts I have been having!
                    >
                    >Matt
                    >
                    >
                    >
                    >

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