How to Measure Residual Sugar?

Discussion in 'Yeast, Additives & Wine Making Science' started by bkisel, May 26, 2016.

  1. bkisel

    bkisel Junior Member

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    Is there a simple way to measure residual sugar? Maybe with just a hydrometer? Wouldn't the measurement be of the sugar left after fermentation PLUS any sugar from back sweetening?

    [The Wine Entry Form for the up coming Canton Wine and Cheese Festival requires the % Residual Sugar be listed. FYI... "12. The categories for judging are Dry/Semi-Dry (Less than 3% residual sugar) and
    Sweet/Dessert (3.1% or more residual sugars.)"]

    Thanks...
     
    Last edited: May 26, 2016
  2. Deezil

    Deezil Moderator Super Moderator

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    If I remember right, it's roughly the Brix measurement

    5 Brix = 5% residual sugar = ~50 grams sugar/liter

    It's not exact, because ABV plays a role too - but for the life of me, I can't find the formula that takes ABV into consideration
    And my brain is fried from college, so I can't piece it together myself at the moment
     
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  3. NorCal

    NorCal Super Moderator Super Moderator

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    That's how I figure.
     
  4. bkisel

    bkisel Junior Member

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    That should be close enough. So find my final SG, after any back sweetening, then rotate the hydrometer and read the Brix.

    Thanks...
     
  5. NorCal

    NorCal Super Moderator Super Moderator

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    Not sure it is even that complicated and sure there will be some margin of error due to the % alcohol, but drop the hydrometer in the must and read the brix add some sugar and stir, the brix will rise and be immediately evident. It is easier with precision hydrometers; I have one that goes from -5 to 5 brix, so it is pretty accurate.
     
  6. richmke

    richmke Member Supporting Member

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    > Wouldn't the measurement be of the sugar left after fermentation PLUS any
    > sugar from back sweetening?

    How do you propose the measure the "sugar left after fermentation"?

    The measurements from a Refractometer and a Hydrometer presumes the absence of alcohol. Once fermentation starts, you need to know the original SG in order to estimate the current alcohol level in order to adjust the reading to get the current sugar level. If you add sugar along the way, that makes the adjustment even more complicated.

    > The Wine Entry Form for the up coming Canton Wine and Cheese Festival requires
    > the % Residual Sugar be listed.

    Assuming that you are not on the edge of one category, your can "estimate" the residual sugar from the SG.

    Assume that 0.992 SG is 0% sugar. Current SG - 0.992 = approximate residual sugar level. If you are 2.5% or lower, or 3.5% or higher, then you should be fine. If you are right on the edge of 3.0%, then you might need a more refined analysis.
     
    Last edited: May 27, 2016
  7. Runningwolf

    Runningwolf Super Moderator Super Moderator

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    Use a clinitest to measure sugar
     
  8. Johny99

    Johny99 Junior Member Supporting Member

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    Yup, clinitest

    I agree. The physics of a hydrometer with anything other than pure water get very complicated. Not worth the effort between alcohol, and remember there are different ones, solids, temperature, and other density changing stuff. A clinitest is cheap reliable and if you are careful, pretty accurate. The alternative is a test lab. The one here is like $40 bucks for a pretty complete panel. Sure adds to the cost of entry tho!
     
  9. bkisel

    bkisel Junior Member

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    This is beginning to bother me. Not the responses themselves to my question but the feeling I'm getting that it's just not worth going through the hassle to enter a bottle of my wine into this amateur wine contest.
     
  10. Deezil

    Deezil Moderator Super Moderator

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    If you're not messing with the Feds, a hydrometer should work just fine.

    This isn't rocket science, and it's not gonna blow up if you're off by a few points either way

    Use the Brix measurement for anything non-commercial
    Use a Clinitest tablet if you wanna be 'spot on'
     
  11. NorCal

    NorCal Super Moderator Super Moderator

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    Everyone else entering is in the same boat as you, but probably haven't thought through it as much as you.
     
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  12. bkisel

    bkisel Junior Member

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    Last edited: Jun 6, 2016
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  13. we5inelgr

    we5inelgr Senior Member

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    Resurrecting this thread as it seems Clinitest is discontinued again. Any alternatives to it?
     
  14. we5inelgr

    we5inelgr Senior Member

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    Since Clinitest was discontinued by the manufacturer (Bayer), AimTab Tablets are a current alternative sold at the Vintner's Vault for 36 tabs/$38.99.

    Another source, Medixcorp has the AimTab's at 36 tabs/$26.75.

    Use the same procedure & color chart as Clinitest.

    Note: There are other testing tablets made by the Germaine manufacturer (ex. Keytone test tablets) with packaging that looks identical.
    When ordering, make sure your getting their 'AimTab Reducing Substances Tablets' for testing sugars (Glucose, Lactose, Fructose, Galactose).
     
    Last edited: Jan 11, 2018
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