Wort stratification?

[DuncB]

Slightly off topic, but if you have a hop spider and are adding sugars to the boil kettle with the element on, putting the sugar into the hop spider allows dissolving and distribution to occur and less chance of scorching on the bottom of the kettle.

 

[mac_1103]

I don't think spontaneous stratification of homogeneous solutions happens over the heights involved in brewing

Or over the time intervals involved in brewing. As I'm sure you know, homogeneous solutions of things like sucrose and heavy metal ions can be made to stratify, but that usually involves ultracentrifugation. Should we have a poll to predict the result of your experiment?

 

[doug293cz]

@doug293cz

A partly filled hydrometer cylinder with 1.030 and then add some sugar or syrup. Test after rest would be closer to the OP issue.
Or am I missing something?

Agree that OP's issue may have been due to incomplete mixing (lack of homogeneity) prior to sampling - which is a real thing, but the discussion moved to stratification of homogeneous solutions - does it happen or not? That is what the experiment is designed to test.

Edit: Another experiment that might be interesting is to put sugar in the bottom of a hydrometer test cylinder, and add water without any stirring. Then monitor over time to see if the solution eventually reaches the SG that would correspond to complete homogenization. Diffusion in liquids is just like diffusion in gasses, just a lot slower (absent any currents or other mixing.)

Brew on

 

[sibelman]

There's the theoretical, and the practical (for homebrewers). The question prompted by OP but broadened somewhat (guilty!): stratification over "short" time periods and in "small" containers: seconds/minutes in a hydrometer sample jar, minutes/hours/days in a kettle/fermenter.

 

[DuncB]

Agree that OP's issue may have been due to incomplete mixing (lack of homogeneity) prior to sampling - which is a real thing, but the discussion moved to stratification of homogeneous solutions - does it happen or not? That is what the experiment is designed to test.

Edit: Another experiment that might be interesting is to put sugar in the bottom of a hydrometer test cylinder, and add water without any stirring. Then monitor over time to see if the solution eventually reaches the SG that would correspond to complete homogenization. Diffusion in liquids is just like diffusion in gasses, just a lot slower (absent any currents or other mixing.)

Brew on

I'd suggest some bleach in the water for this experiment otherwise ferment is going to kick off, or start sterile and keep it sterile, not sure how to sterilise sugar crystals though ( apart from radiation)!

 

[doug293cz]

I'd suggest some bleach in the water for this experiment otherwise ferment is going to kick off, or start sterile and keep it sterile, not sure how to sterilise sugar crystals though ( apart from radiation)!

Yeah, this crossed my mind after I started mixing the solution. If the flask I'm stirring it in will fit in the microwave, I'll give it a quick boil. Won't take the initial refractometer reading until after it's boiled.

Brew on

 

[DuncB]

A few drops of coloured bleach on the top might make it interesting!!

 

[doug293cz]

A few drops of coloured bleach on the top might make it interesting!!

Too late. Initial Brix reading after filling cylinder was 16.6. Apparently I lost a bit more water than expected during the sanitize boil. Refract calibrated immediately before taking multiple readings. Now we wait.

Brew on

 

[doug293cz]

Reading after ~48 hours is still 16.6 for sample taken from the top of the cylinder. Again, refract calibrated immediately prior to sample measurement. Zero evidence of stratification yet.

Brew on

 

[sibelman]

I'm imagining a ~5 gallon version of this test with, say, 10 lbs of malt. Stir boiled wort very well, read gravity (hydrometer and/or refractometer), wait, measure again.

Dunno if Doug's small test eliminates the benefit of a bigger test, though. Thoughts?

Preventing fermentation could be a challenge even though the wort has been boiled, as wild yeast or bacteria might infect the experiment. Thoughts?

 

[worlddivides]

As the OP, I will mention that so far that batch is still the only instance of that occurring that I've experienced so far. As mentioned earlier on in the thread, since I couldn't determine whether stratification had actually occurred or not (and if it had occurred, I couldn't be sure what the actual gravity was), I just used the unusually low gravity reading as the actual reading, but I ended up adding the equivalent of 3 more gravity points of sugar during the height of fermentation, which basically meant I only had 0.5% less ABV than as expected instead of 1.0% or 1.1% less than expected. Looking at my records, the batch immediately before that one had an expected gravity of 1.040, but I got 1.042. And the batch immediately after that one had an expected gravity of 1.051 and I got 1.049. A 2 point difference is extremely common, 3 points happens every now and then, and at least in my personal case I think 4 is the biggest difference I've had in a system that I'm familiar with before this massive 7 point difference, but I'm not sure what caused such a massive difference in gravity, especially given me mashing 20 minutes longer than usual. If stratification was not a factor (and it just visually looked stratified for whatever reason), maybe the coarser grind was too coarse for the extra 20 minutes to have made a significant difference.

 

[doug293cz]

Reading after ~48 hours is still 16.6 for sample taken from the top of the cylinder. Again, refract calibrated immediately prior to sample measurement. Zero evidence of stratification yet.

Brew on

Here's a pic of the experimental apparatus. The cylinder is kept covered, as shown, to avoid evaporation. Sugar and water were mixed on a stir plate for over an hour before boiling. The liquid column is just under a foot high, and I go to great pains to avoid jostling the cylinder when moving it in and out of the corner where it sits when take samples.

At the end of this experiment (probably Sunday night, 8/10) I will take a sample from close to the bottom using a long narrow straw. Sample procedure will be to place a finger over the top end of the straw to prevent liquid from entering until the tip of the straw is as deep as it can go into to solution.

Brew on

 

[DuncB]

@worlddivides

Can you take a refractometer and hydrometer reading of your finished beer?

If you can do this then you can work out the ABV and consequently the true OG with compensation for your added sugar.

 

[BrewnWKopperKat]

@DuncB @worlddivides This calculator may be helpful

https://www.northernbrewer.com/pages/refractometer-calculator

 

[DuncB]

Thanks several about, I use this one recommended by @VikeMan

https://www.vinolab.hr/calculator/alcohol-from-hydrometer-refractometer-en27

 

[doug293cz]

I'm imagining a ~5 gallon version of this test with, say, 10 lbs of malt. Stir boiled wort very well, read gravity (hydrometer and/or refractometer), wait, measure again.

Dunno if Doug's small test eliminates the benefit of a bigger test, though. Thoughts?

Preventing fermentation could be a challenge even though the wort has been boiled, as wild yeast or bacteria might infect the experiment. Thoughts?

Why would you think that increased dimensions in the horizontal direction would have any affect on something that would occur only in the vertical direction, if it occurs at all?

Brew on

 

[worlddivides]

@worlddivides

Can you take a refractometer and hydrometer reading of your finished beer?

If you can do this then you can work out the ABV and consequently the true OG with compensation for your added sugar.

I've never taken a refractometer reading of finished beer before since, as far as I'm aware, the presence of alcohol makes whatever values it gives completely inaccurate. The OG was 1.033. I assumed that the sugar I added brought it up to 1.036. Then the final hydrometer reading was 1.005 for about 86% apparent attenuation and an ABV of around 4.07%, assuming that both there was no actual stratification and the sugar added did add exactly 3 points of gravity.

I still have 2 bottles left of that beer. I don't expect the hydrometer reading would be any different, but would there be any benefit to taking a refractometer reading?

EDIT: Wait. If I'm reading this right, does that mean it's possible to tell the ABV of a fermented beverage without taking a gravity reading at the start, but by taking gravity readings both with a refractometer and a hydrometer when it's done? If that's possible, that's actually pretty fascinating and I'd want to try that out. It's just this is the first I've heard of that even being possible. I'd always heard that you shouldn't use a refractometer after fermentation started (or I guess after adding the yeast).

 

[day_trippr]

As DuncB stated, you can indeed determine the ABV without knowing the OG...

Cheers!

 

[worlddivides]

As DuncB stated, you can indeed determine the ABV without knowing the OG...

Cheers!

I wonder why I'm just hearing about this now for the first time. Also, I'm curious just how accurate it can calculate the initial gravity and current ABV...

I'm not going to take a hydrometer reading with that beer, but I'll try to remember to take a Brix reading with my refractometer when I open the next to last bottle.

 

[day_trippr]

It's apparently a rather rarely used technique as there's been precious little discussion about it here - for as long as I've been around it's only been mentioned a handful of times iirc. Tbh I've never even considered it because I'm a stickler for data - I'd likely "forget the bittering hops" before I failed to take an OG reading

Cheers!

 

[worlddivides]

I've never forgotten to take a gravity sample before pitching the yeast (though I've almost forgot one or two times), so the main usefulness of the technique for me would be in cases where I added some form of sugar near the end of fermentation. Up until now, I've just guessed at what the gravity is for those. Say, I have a 1.040 OG, then add 500 grams of mango puree at the tail end of fermentation, then check the FG and it's 1.010. My ABV is definitely higher than the 3.94% that just the OG and FG would suggest. Normally I'd just adjust the OG in accordance to how much sugar was in the puree added to the amount of liquid in the fermenter, but being able to get a somewhat accurate ABV reading just based on a final gravity and Brix reading would be especially useful in cases like this.

 

[doug293cz]

After ~72 hrs, the Brix reading is still 16.6. No spontaneous stratification. I'll take one final reading after another ~48 hrs.

Brew on

 

[sibelman]

Why would you think that increased dimensions in the horizontal direction would have any [e]ffect... ?

Indeed. When I saw your photo of test jar with ruler, this clicked for me. No benefit from a 5 gallon test.

Assuming your preliminary result is also how things will look at the end of the experiment, it seems that pre-fermentation changes in SG of well-stirred wort at homebrew scales will come from settling of particulates, not from stratification.

 

[doug293cz]

Indeed. When I saw your photo of test jar with ruler, this clicked for me. No benefit from a 5 gallon test.

Assuming your preliminary result is also how things will look at the end of the experiment, it seems that pre-fermentation changes in SG of well-stirred wort at homebrew scales will come from settling of particulates, not from stratification.

Yup.

Brew on

 

[VikeMan]

I've never taken a refractometer reading of finished beer before since, as far as I'm aware, the presence of alcohol makes whatever values it gives completely inaccurate.

The alcohol component does indeed throw in a monkey wrench, because it has a different refractive index than sugars. Fortunately, the brewing refractometer calculators (not the simple "brix to SG" converters) take that into account and usually produce a reasonable estimate of the FG, and thus the ABV. Some people are leery of this, because of the (true) assertion that alcohol affects the measurement. That said, alcohol also affects hydrometer measurements (but in a different way). It's why we can have hydrometer FG readings that are lower than 1.000. However, the hydrometer ABV calcs also take that into account.

so the main usefulness of the technique for me would be in cases where I added some form of sugar near the end of fermentation. Up until now, I've just guessed at what the gravity is for those. Say, I have a 1.040 OG, then add 500 grams of mango puree at the tail end of fermentation, then check the FG and it's 1.010. My ABV is definitely higher than the 3.94% that just the OG and FG would suggest. Normally I'd just adjust the OG in accordance to how much sugar was in the puree added to the amount of liquid in the fermenter

For fruit additions, it's a mistake to simply add in the sugar component without also taking into consideration the water component of the fruit. Quite often, adding fruit actually decreases the ABV. Whether it increases or decreases depends on the base beer and it depends on the fruit. There's a lengthy and possibly insomnia curing discussion of this concept in this BYO article, which appears to not be behind the firewall at the moment: https://byo.com/article/ciphering-fruit-beers/

I highly recommend that article, as the author is absolutely brilliant. Brilliant, I say!

There's a free excel calculator called FruitCalc that implements the model presented in the article. You can download it here (among other places): https://sonsofalchemy.org/library/ Be wary of other fruit addition calculators...if every fruit you try increases ABV for every base beer you try, it's a bad calculator. This was actually the major reason for the article (and the model) in the first place.

 

[worlddivides]

Good point. All fruit is high in water, after all, and different fruits have different amounts of water. Purees may be lower in water than the raw fruit, but there's still a decent amount of water in there. I think that's another reason why this method could be pretty helpful in knowing the actual ABV -- or at the very least, a more accurate estimate of the ABV than my guesswork gets at.

 

[BrewnWKopperKat]

EDIT: Wait. If I'm reading this right, does that mean it's possible to tell the ABV of a fermented beverage without taking a gravity reading at the start, but by taking gravity readings both with a refractometer and a hydrometer when it's done? If that's possible, that's actually pretty fascinating and I'd want to try that out. It's just this is the first I've heard of that even being possible. I'd always heard that you shouldn't use a refractometer after fermentation started (or I guess after adding the yeast).

Petr Novotny (Zymurgy article (paywall)) and Sean Terrill (web article via Internet Archives) from about 2017 would be good starting points. I would avoid seanterrill(dot)com as it may have been compromised - it displayed a very novel "verify you are human" page on the second page that I looked at.

You could also use HomeBrewTalk's site search on those two names.

 

[ncbrewer]

Preventing fermentation could be a challenge even though the wort has been boiled, as wild yeast or bacteria might infect the experiment. Thoughts?

I agree it’s possible that wild yeast or bacteria could infect it. But that would lower the SG, so no change in SG should still indicate no stratification. A drop in SG could indicate either stratification or infection (or so it seems).

 

[doug293cz]

I agree it’s possible that wild yeast or bacteria could infect it. But that would lower the SG, so no change in SG should still indicate no stratification. A drop in SG could indicate either stratification or infection (or so it seems).

Correct. This is one of the reasons I will be taking a sample from deeper in the cylinder after the final 120 hr top measurement. If the top shows a drop in SG but the deeper sample does not, then that would be an indication of stratification. If both samples show similar drops, then it's probably wild fermentation rather than stratification. Simplest outcome is no change for either reading.

Brew on

 

[DuncB]

The Anton paar refractometer and " densitometer " I saw on a video can give the alcohol reading if both are used and the app works it out.
This is a lot more expensive than the simple refractometer and hydrometer reading into the formula.