Author Topic: Does yeast in suspension effect hydrometer reading  (Read 1998 times)

Offline denny

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Re: Does yeast in suspension effect hydrometer reading
« Reply #15 on: February 09, 2018, 08:02:59 PM »
You guys go ahead...I've done this.
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Online klickitat jim

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Re: Does yeast in suspension effect hydrometer reading
« Reply #16 on: February 09, 2018, 08:03:13 PM »
You betcha, Jim! 

My hypothesis would be:  1) of course anything but water in water makes it denser 2) any instrument that measures density will, with proper use, reflect that equally well (no preferred instrument) and 3) at the point you are taking FG readings there will be so little suspended yeast left, that it will be an insignificant contributor to the density of the sample, far smaller than the margin of error in just reading the instrument (unless that instrument costs as much as your house and is in a university lab.) 

A method that might throw light on this is to take a FG sample and measure it, then refrigerate it for a few days to settle any yeast and read again.  The problem I see with this is the possibility of continued fermentation.  I may not be able to contribute much there, because a) I take my sample after crash cooling anyway and b) I know my yeast (34/70) will in fact keep fermenting after crashing.

 But hopefully you'll get enough citizen brewing scientists going here to get a real answer!  As OP you are the official proctor.  Good luck.
Your making assumptions. I could do that too. But it's not proving or disproving anything. How do we know that our green hazy beer does not have enough suspended solids, regardless if it's yeast, protein, starch, hop polyphenols, to effect our hydrometer reading? What instrument or calculus are we using to determine that?

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Re: Does yeast in suspension effect hydrometer reading
« Reply #17 on: February 09, 2018, 08:04:53 PM »
You guys go ahead...I've done this.
What did you do and what did you find?

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Re: Does yeast in suspension effect hydrometer reading
« Reply #18 on: February 09, 2018, 08:06:12 PM »
Glycogen + water --> glucose (which is sugar)

I think we need to re-design the experiment to use cruddy old spent yeast, rather than fresh dried yeast.

And... it so happens that I currently have a LOT of old yeast, about 1.5 quarts of it, from a batch I just racked off last night and did NOT package the yeast yet.  It's still in the carboy, ready for experiments.  Mua ha ha ha ha!!
To achieve 1.010 that yeast I used would have to be 100% cane sugar

Offline gman23

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Re: Does yeast in suspension effect hydrometer reading
« Reply #19 on: February 09, 2018, 08:18:38 PM »
I know the answer
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Re: Does yeast in suspension effect hydrometer reading
« Reply #20 on: February 09, 2018, 08:24:22 PM »

Offline gman23

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Re: Does yeast in suspension effect hydrometer reading
« Reply #21 on: February 09, 2018, 08:26:32 PM »
On Tap/Bottled: Kurbis Marzen, Red Rye, Vienna Lager, Dry Hopped Peach Cider       

Fermenting: Imperial Porter, Hopfenbier
Up Next: Maibock, Braunbier

Offline charles1968

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Re: Does yeast in suspension effect hydrometer reading
« Reply #22 on: February 09, 2018, 08:28:26 PM »
You could filter the yeast suspension through a coffee filter. Dissolved carbohydrates and salts will pass through, suspended particles won't. Then take gravity of the filtrate. I'm 99% sure it will be higher than distilled water.

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Offline dmtaylor

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Re: Does yeast in suspension effect hydrometer reading
« Reply #24 on: February 09, 2018, 08:32:07 PM »
Dave

The world will become a much more pleasant place to live when each and every one of us realizes that we are all idiots.

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Re: Does yeast in suspension effect hydrometer reading
« Reply #25 on: February 09, 2018, 08:34:03 PM »
You could filter the yeast suspension through a coffee filter. Dissolved carbohydrates and salts will pass through, suspended particles won't. Then take gravity of the filtrate. I'm 99% sure it will be higher than distilled water.
Go for it. But also measure it as is. So just water, water with yeast, then that water minus yeast. Probably don't even need to filter, just let it settle to the bottom. Will there be a difference between in suspension and settled out? I suspect yes.

Offline Robert

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Re: Does yeast in suspension effect hydrometer reading
« Reply #26 on: February 09, 2018, 08:37:20 PM »
You betcha, Jim! 

My hypothesis would be:  1) of course anything but water in water makes it denser 2) any instrument that measures density will, with proper use, reflect that equally well (no preferred instrument) and 3) at the point you are taking FG readings there will be so little suspended yeast left, that it will be an insignificant contributor to the density of the sample, far smaller than the margin of error in just reading the instrument (unless that instrument costs as much as your house and is in a university lab.) 

A method that might throw light on this is to take a FG sample and measure it, then refrigerate it for a few days to settle any yeast and read again.  The problem I see with this is the possibility of continued fermentation.  I may not be able to contribute much there, because a) I take my sample after crash cooling anyway and b) I know my yeast (34/70) will in fact keep fermenting after crashing.

 But hopefully you'll get enough citizen brewing scientists going here to get a real answer!  As OP you are the official proctor.  Good luck.
Your making assumptions. I could do that too. But it's not proving or disproving anything. How do we know that our green hazy beer does not have enough suspended solids, regardless if it's yeast, protein, starch, hop polyphenols, to effect our hydrometer reading? What instrument or calculus are we using to determine that?
I said it's a hypothesis, that's my point, it needs to be tested.  Somehow we need to see what yeast all by itself does, because we expect all that other stuff to be in there too.  (And in the end, if you know that x APPARENT  attenuation means it's time to rack, does it matter what all the floaties are, or the REAL attenuation?)  Still this will be good to know.  Everything's good to know!  Looking forward to it.
Rob Stein
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Offline denny

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Re: Does yeast in suspension effect hydrometer reading
« Reply #27 on: February 09, 2018, 08:38:21 PM »
You could filter the yeast suspension through a coffee filter. Dissolved carbohydrates and salts will pass through, suspended particles won't. Then take gravity of the filtrate. I'm 99% sure it will be higher than distilled water.

pretty much what I did after cold crashing for a few days.  I took a cloudy post boil sample with a lot of suspended "gunk" and measured it.  I chilled it for 2-3 days, filtered it, them measured it again.
« Last Edit: February 09, 2018, 08:40:06 PM by denny »
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Re: Does yeast in suspension effect hydrometer reading
« Reply #28 on: February 09, 2018, 08:50:09 PM »
Here's water 1.000 compared to water with a half tsp of white flour suspended 1.004. I'll let it settle out and check again. I'm doubtful that 1 min in 68F water is enough to convert flour to sugar.

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Re: Does yeast in suspension effect hydrometer reading
« Reply #29 on: February 09, 2018, 08:59:18 PM »
Flour settled to bottom, new reading