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Thread: Sulfur dioxide endogenous production

  1. #1
    Join Date
    Jan 2003
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    2

    Lightbulb Sulfur dioxide endogenous production

    Hello!

    Have anyone ever tried sulfur dioxide endogenous īcontrolledī production in beer? Does anyone have info about it (to induce it)? (the idea is to protect beer against oxidation as in wine, but with endogenous SO2)

    Thanks!

  2. #2
    Join Date
    Oct 2002
    Location
    Tadcaster, Yorkshire, UK
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    1,042
    Hmmmm. I'm intrigued. I have never heard of this happening. Does it happen in the wine industry ? If so what are the conditions?

    My own thoughts are that this is not going to happen. Firstly, to be able to get SO2 produced you will need a source of sulphur and non oxidising conditions. Yeast requires oxygen in reasonably large quantities at the start of fermentation at least, the level depending upon yeast strain, wort strength and fermenting conditions, purely to grow, and ferment, i.e. simply to produce beer. Whenever I have come across high sulphur levels it is because of high levels of calcium sulphate (gypsum) in the brewing liquor. which ends up producing not SO2, but H2S - distinctly different and less pleasant, although amy be consisdered by some to give a fuller bodied beer when present in very small quantities.

    From experience of adding SO2 as an anti-oxidant in relatively high quantities, if yeast is present it seems to generate H2S, and if no yeast is present, the beer still doesn't taste particularly good - too much SO2. I think this is one reason for using other antioxidants such as ascorbic acid (though this also has its problems)

    I think you are better off paying close attention to oxygen control, particularly pickup post primary fermentation than try to generate a by product which can cause off flavours.

    Having said all that, if anyone has heard of such conditions suitable to produce SO2, I would love to hear, as the potential is enormous if it sould be controlled properly.

    Cheers
    dick

  3. #3
    Join Date
    Feb 2003
    Location
    Portland,Oregon
    Posts
    2
    In the wine industry SO2 is generally added in the form of liquid SO2 or K2SO5 potassium metabisulfite solution after the yeast has been filtered to avoid H2S problems. The amount of SO2 added depends on the pH usually below 3.8. If your beer has a pH of 4.5 you might need twice the amount of SO2 than a typical wine pH of3.5 to acheive the same amount of protection against oxidation. If yeast is still present then keeping the beer in full tanks (no headspace) and bubbling CO2 through should help minimize oxidation, even spent yeast can still grab some O2 out of solution.

  4. #4
    Join Date
    Jan 2003
    Posts
    2
    Thanks for your replay.
    I didnīt mean that the wine industry is producing endogenous SO2 (in a controlled way) I was just talking about the use of SO2 in wine.
    I have read some articles about this topic, and they mentioned something about strains that could be genetically modified to produce more SO2, and about some factors that may improve SO2 production (strain, pH, O2 level, sulfate level, levels of methionine and cysteine that yeast would have to produce-of course it is because SO2 and H2S are subproducts of the sulfate assimilation to produce the aminoacids-).
    I just was wondering if anyone have tried something in order to get a certain level of SO2, I mean, the highest level before H2S bad flavor appear.

    Thanks,
    Tere

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