Does yeast in suspension effect hydrometer reading

[klickitat jim]

Flour settled to bottom, new reading

How long did that take?  There's a lot of flour at the bottom, so another hypothesis is that enough flour temporarily provides nucleation points for rising dissolved gasses and due to surface tension lifts the refractometer.  Any ideas how to test this?

Also, ascorbic acid which is in dry yeast as an antioxidant is soluble in water and is a derivative of glucose.  How much is in there, I don't know. 

Code: [Select]

Ascorbic acid (vitamin C, C6H8O6)is a water-soluble vitamin. A solution containing 81.0g of ascorbicacid dissolved in 230g of water has a density of 1.22g/mL at55oC.

Took about 5 min to settle


People can believe whatever they want. In my brewery, suspended solids effect the hydrometer reading.

[narvin]

People can believe whatever they want. In my brewery, suspended solids effect the hydrometer reading.

It's not that I don't believe you.  Just trying to figure out how much these tests relate to actual brewing conditions.

How does a fresh sample from the fermenter compare to a sample that has crash cooled for 24 hours?

[dmtaylor]

I have conducted the flour experiment.  Water read 1.001.  Water plus a lot of flour read 1.012.  After waiting 15 minutes, water plus settled flour read 1.004.

So yeah.  Suspended solids can change the gravity.  Some of the poodles are holding up the hydrometer... for a little while.  Once settled out, they don't anymore.

I could repeat the experiment with yeast, but I'm sure I'd get the same results.

What does this matter?  Well... if your beer is as murky as a juicy fresh NEIPA, it might matter.  Also if you're measuring gravity in early primary fermentation stage, it might not be so accurate.    But any other fully fermented beer style...... no impact at all, I don't think.  Maybe 0.001.  But not enough to matter.  My 1.004 flour stuff settled for 15 minutes was still fairly murky, and that was only 0.003 higher than expected (subtracting 1.001 for the reading in plain water).  So.

[klickitat jim]

People can believe whatever they want. In my brewery, suspended solids effect the hydrometer reading.

It's not that I don't believe you.  Just trying to figure out how much these tests relate to actual brewing conditions.

How does a fresh sample from the fermenter compare to a sample that has crash cooled for 24 hours?

Simple way to know. Measure both.

I was unaware that suspended solids did this. Then last week I heard Palmer say that he was working on figuring out NE IPAs. He tested water with starch in suspension and it read 1.010, but 1.000 after it settled to the bottom.

Sometimes I take readings during fermentation to determine rate of fermentation, and ADF to determine when to increase temp. Those samples can be quite full of suspended solids. So the hydrometer reading can't be relied on. I'm finding that a better method is to pull a tiny sample, which chills and settled faster, and take a refractometer reading and use a calculator to adjust for alcohol.

[narvin]

People can believe whatever they want. In my brewery, suspended solids effect the hydrometer reading.

It's not that I don't believe you.  Just trying to figure out how much these tests relate to actual brewing conditions.

How does a fresh sample from the fermenter compare to a sample that has crash cooled for 24 hours?

Simple way to know. Measure both.

I was unaware that suspended solids did this. Then last week I heard Palmer say that he was working on figuring out NE IPAs. He tested water with starch in suspension and it read 1.010, but 1.000 after it settled to the bottom.

Sometimes I take readings during fermentation to determine rate of fermentation, and ADF to determine when to increase temp. Those samples can be quite full of suspended solids. So the hydrometer reading can't be relied on. I'm finding that a better method is to pull a tiny sample, which chills and settled faster, and take a refractometer reading and use a calculator to adjust for alcohol.

Suspended solids of large size fall out pretty quickly, though.  I'm more interested in the effect of something that can stay in suspension after 24 hours of chilling.

EDIT: I can see how this might affect fermenting beer, where yeast tends to stay in suspension.  Although I'm already 100% on the refractometer train for that since it's so much easier to take a sample.

[dmtaylor]

Suspended solids of large size fall out pretty quickly, though.  I'm more interested in the effect of something that can stay in suspension after 24 hours of chilling.

Way too small to measure is my guess.  Doesn't even warrant an xbmt in the opinion of yours truly.

[klickitat jim]

People can believe whatever they want. In my brewery, suspended solids effect the hydrometer reading.

It's not that I don't believe you.  Just trying to figure out how much these tests relate to actual brewing conditions.

How does a fresh sample from the fermenter compare to a sample that has crash cooled for 24 hours?

Simple way to know. Measure both.

I was unaware that suspended solids did this. Then last week I heard Palmer say that he was working on figuring out NE IPAs. He tested water with starch in suspension and it read 1.010, but 1.000 after it settled to the bottom.

Sometimes I take readings during fermentation to determine rate of fermentation, and ADF to determine when to increase temp. Those samples can be quite full of suspended solids. So the hydrometer reading can't be relied on. I'm finding that a better method is to pull a tiny sample, which chills and settled faster, and take a refractometer reading and use a calculator to adjust for alcohol.

Suspended solids of large size fall out pretty quickly, though.  I'm more interested in the effect of something that can stay in suspension after 24 hours of chilling.

Agreed. Like polyphenols... they can be filtered/centrifuged out, so they're not in "solution". I don't have the equipment to really test that. But at this point, I'm going with they "probably" have some effect.

[erockrph]

So, does this mean that we have been underestimating the attenuation of hefe's and witbiers? Is a hazy beer actually more attenuated than calculated? Interesting food for thought here.

[klickitat jim]

Maybe, and probably

[dmtaylor]

Probably not, unless EXTREMELY murky.

[klickitat jim]

Depends on how much effect is important to you. Would there be ANY effect? Probably. Enough to matter to you? Depends, I don't know what that would be.

[charles1968]

This makes me wonder if bubbles of gas can have the opposite effect. The reason fermenting beer has a lot of suspended matter is that hundreds of CO2 bubbles are rising through the liquid and creating currents, a bit like convection currents. Is there enough gaseous CO2 (as opposed to dissolved CO2) to lower the gravity and cancel out the effect of sediment raising gravity?

[erockrph]

This makes me wonder if bubbles of gas can have the opposite effect. The reason fermenting beer has a lot of suspended matter is that hundreds of CO2 bubbles are rising through the liquid and creating currents, a bit like convection currents. Is there enough gaseous CO2 (as opposed to dissolved CO2) to lower the gravity and cancel out the effect of sediment raising gravity?

I've always tried my best to knock the carbonation out of gravity samples for just this reason.

[klickitat jim]

Seems like gas bubbles would lift the hydrometer not pull it down

[Robert]

Seems like gas bubbles would lift the hydrometer not pull it down

Yep, that's what they do.  They're antipoodles: they are distributed through the volume, and do lower the AVERAGE density of the whole container load of stuff, but like regular poodles, they lift the hydro, often significantly.  You can give it a good spin and detach most of them.