Gravity question

Discussion in 'General Brewing Discussions' started by jeffpn, May 14, 2018.

  1. jeffpn

    jeffpn Well-Known Member

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    After my boil, I let my chilled wort sit a few hours so the trub (sediment if you don’t like that term) settles. My question is, what is the sugar doing? Is it settling, too? Will I not get an accurate gravity reading if I gather the sample from the top, or from the bottom? I’m not going to stir the wort, as that will just resuspend all of the trub.
     
  2. Beer_Pirate

    Beer_Pirate Active Member

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    With absolutely no scientific data to back this up, my initial thought is that since sugar is highly soluble, the solution (wort) should be homogeneous. My first thought was sweet tea (sitting in the fridge doesn't make the bottom of the pitcher any sweeter than the top).
     
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  3. Trialben

    Trialben Well-Known Member

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    this is how my peanut see it:p the sugar was a partical but now its in a different state in the water as maltose dectrose sucrose ect which are all soluble in water just like the hop oils and brew salts. so they (i think) evenly distribute themselves through the wort profile maybe some sugars are more dense than others being more complex like maltose so they may eventualy stratify. this is my poke in the dark on it all.

    come on Noseybear;)!
     
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  4. jeffpn

    jeffpn Well-Known Member

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    Yeah, I don’t know how that works. You often see seasoned brewers tell new brewers to mix in the priming sugar solution well, otherwise you won’t get consistent carbonation across the batch, as the sugar tends to settle over time. If priming sugar settles, why wouldn’t wort sugar?
     
  5. Trialben

    Trialben Well-Known Member

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    same as us AG brewers taking gravity reading "give it a good top to bottom stir to get all the sugars evenly distributed". you do pose an interesting question jeffpn and i for one would feel like i may have got a slightly wrong reading taken from settled wort.
     
  6. jeffpn

    jeffpn Well-Known Member

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    I’d love it if that is the explanation for my gravity being lower than expected!

    I don’t know what you mean by all grain brewers stirring well before taking a gravity reading. This would apply to extract brewers as well. Sugar is sugar, regardless of how you got it.
     
  7. Beer_Pirate

    Beer_Pirate Active Member

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    It's a little different when you're mixing two solutions prepared independently than when the wort is just left to rest. Imagine adding sugar (or simple syrup for consistency) to room temperature water vs having a simple syrup already prepared.
     
  8. jeffpn

    jeffpn Well-Known Member

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    Assuming that the priming sugar solution is mixed perfectly well into the wort, it shouldn’t settle if sugar doesn’t settle. But it’s a concern when bottling. So should it be a concern in your wort when taking a gravity reading?
     
  9. Trialben

    Trialben Well-Known Member

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    i knew when i typed that youd mention it jeff predictable but right doent matter AG or extract is same. but as pirate stated above.slightly differnt as mash water is consistent temp were extract is differnet temp solutions mixed in .
     
  10. Beer_Pirate

    Beer_Pirate Active Member

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    If it's mixed perfectly well into the wort, I wouldn't think it's an issue no matter what. Part of this may be that the older brewing books and instructions just said to throw some (solid) sugar in and give it a stir, whereas now it's common practice to make a sugar solution and add it for easier mixing/solubility.
     
  11. jeffpn

    jeffpn Well-Known Member

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    I always boiled water for my priming sugar solution. I don’t know how old Charlie P’s book is, but I had that book in 1995 when I brewed my first batch. And that’s what the extract kit instructions said as well, to boil water to more easily dissolve the sugar. I don’t know how relevant different temperature solutions are, either. As you mix them, they become the same temperature.
     
  12. Beer_Pirate

    Beer_Pirate Active Member

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    Temperature aside (whole different topic than the point I was getting at), the wort has its own density, the OG. The only thing that should (in theory) rise or sink in it is something that isn't in solution, i.e. trub/sediment. When you mix in priming solution it also has its own density, and without putting some energy into the system these two solutions could stratify instead of mixing. The priming solution has an insanely high density in terms of beer and needs to be mixed in to avoid this layering effect. The boil provides this mixing effect for the wort (convection and whatnot).
     
  13. Trialben

    Trialben Well-Known Member

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    even taking the gravity sample a hydrometer uses more wort than refractometer im guessing that for a refractometer sample its just a pipet from top/surface then dropped onto refrac so im thinking even more chance of scewed reading if sugar doesnt distrubute evenly before reading taken..

    then there is the trub in the hydro as jeff has pointed out in past that can boost your reading aswell!
     
  14. BOB357

    BOB357 Well-Known Member

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    I believe that trub/break material keeps you from getting a proper gravity reading because it isn't in solution. The sugars and brewing liquor become a solution during the mash. The boil would assure that the solution Is well blended, so stratification isn't an issue. Never thought much about it until I started using a pump and draining it and the outlet hose for my OG sample. Just my sober opinion. Time for a beer now :)
     
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  15. KC

    KC Active Member

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    Sugar is completely soluble, so it will reach equilibrium in solution given sufficient time to do so. This will happen faster in small volumes, at higher temperatures, and/or when manually blended. You can get stratification if there are considerable differences in temperature, concentration, and pressure within a volume. At our scale, this is only temporary.

    Priming sugar is more concentrated and heavier than finished beer so initially it tends to sink in the bottling bucket. It will eventually blend together. The beer is not heated here, so it can take longer than some people are willing to wait. Stirring will reduce that time.

    The high temperature and agitation of a boil ensures sugars are fully mixed, unless you make late additions.
     
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  16. jeffpn

    jeffpn Well-Known Member

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    I don’t think trub/break/sediment affects gravity readings, unless there is so much of it that the hydrometer is sitting on it. Trub is just stuff in the liquid. It doesn’t contribute to the density of liquid like sugar does.
     
  17. Nosybear

    Nosybear Well-Known Member

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  18. Nosybear

    Nosybear Well-Known Member

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    But it does, by a couple of points. I've measured the same wort twice a number of times and have seen that wort with suspended trub is a couple of points denser than clear.
     
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  19. jeffpn

    jeffpn Well-Known Member

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    For all I know, your different gravity readings are due to my theory that sugar settles over time.

    I don’t know about trub affecting gravity readings. It isn’t dissolved into the water. How can it change the density of it? If there is so much trub that it’s wedging the hydrometer against the flask, then it would affect the reading, but not accurately. Or if the hydrometer was sitting on a bed of trub.

    If I had a sample of water with sand shaken up in it, would it be greater than 1.000? Or would you predict a heavier gravity reading until the sand settled completely, and then it’d be 1.000?

    I think the jury is out on that issue. Lots of hits either way on that search.
     
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  20. Hogarthe

    Hogarthe Well-Known Member

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    I don't think the sugar is going to settle while your wort waits. Its dissolved into solution, so unless something happens to cause it to come out of solution, it should stay evenly throughout the liquid. I don't know what could cause it to come out of solution. Like a can of soda has sugar in solution and you drink it weeks after its made, the sugar is still evenly mixed in the soda. It doesn't settle leaving you with a non sweet half and a double sweet half.
     
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