Author Topic: refractometer reading for cloudy weizens  (Read 602 times)

Offline jonnym_ch

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refractometer reading for cloudy weizens
« on: March 21, 2019, 08:02:08 AM »
hi all,
i've just brewed a weizen and added flour at burnout (1tbsp per 5usg) to try and ensure a nice cloudy beer. and i can confirm that it definitely clouded up the wort !

after chilling i took a reading using my refractometer and found i was quite a bit lower than what i was expecting .. just over 1 full brix lower than what was proposed in beersmith. i had hit all my other targets fine and beersmith is reliable for all my other brews.

is this because the flour in the wort is affecting the refractometer reading ? and should i just go with the beersmith calculation and assume that that is correct ?

any thoughts would be much appreciated !

cheers,
jonny

p.s. on a similar note, when i take the gravity reading after lautering (and before boiling) i usually mix up the wort to ensure that the sugar is equally distriuted. this dredges up the gunk from the bottom and i have noticed recently that the readings i take straight after mixing are significantly lower than if i take them after allowing the wort settle and clear ... has anyone else had noticed the same thing ? am i just imagining things ? cheers again !

Offline dtapke

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Re: refractometer reading for cloudy weizens
« Reply #1 on: March 21, 2019, 12:00:05 PM »
I've noticed a similar phenomenon with SUPER hazy ipa's,  it can be checked more accurately after spinning out in a 'fuge, but i still have poor delineation.

as far as your decision to add flour to your beer..... well.... to each their own i guess.
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Offline jonnym_ch

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Re: refractometer reading for cloudy weizens
« Reply #2 on: March 21, 2019, 12:23:25 PM »
thanks dtapke,
good to know i'm not the only one !
guess i'll go with the beersmith estimation, it's normally spot on !
and as for the flour, i was looking for a way to stop the haze dropping out and apparently adding flour at flameout is quite common, even among professional brewers ... and i read it online so it must be true right ?
cheers,
jonny

Offline GigaFemto

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Re: refractometer reading for cloudy weizens
« Reply #3 on: March 21, 2019, 12:30:36 PM »
Cloudiness should not lower the reading of a refractometer, but it will make it very difficult to get a good reading. Imagine a perfectly clear wort that give a sharp transition from white to blue. As you add stuff that scatters the light, the transition will get smeared out, but the center point will remain the same. If you take your reading at the point that you first start to see blue then you will get a value that is too low. You want to use the value in the middle of the transition, where the blue is half as dark as it gets. It can be hard to tell where that is, but that is the correct thing to do.

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Offline Oginme

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Re: refractometer reading for cloudy weizens
« Reply #4 on: March 21, 2019, 12:39:37 PM »
thanks dtapke,
good to know i'm not the only one !
guess i'll go with the beersmith estimation, it's normally spot on !
and as for the flour, i was looking for a way to stop the haze dropping out and apparently adding flour at flameout is quite common, even among professional brewers ... and i read it online so it must be true right ?
cheers,
jonny

The issue that I have with the flour in the beer is that it becomes added food for bacteria and shorted the shelf life of an already tenuous product life span.  The haze in a NEIPA should be from hop glycosides and hop phenols.  Aside from that, the haze should be a side effect and not the defining characteristic of the beer.  But that is just my take on the style.
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Offline jonnym_ch

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Re: refractometer reading for cloudy weizens
« Reply #5 on: March 21, 2019, 01:20:39 PM »
thanks GigaFemto,
wasn't sure if the wort correction was simply to allow for the difference between sugar and maltose solution or if something else could interfere with the reading ... similarly, will a hydrometer react differently to the addition of flour as it surely must change the density of the liquid ?
Oginme - it's interesting to note that the sulphur smell coming from my fermenter are far beyond anything i have had before in a weizen ... seriously bad ! however as the beer is not going to be hanging around long i'm not too worried about shelf life :)
cheers again !
jonny

Offline Oginme

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Re: refractometer reading for cloudy weizens
« Reply #6 on: March 21, 2019, 01:46:53 PM »
I should have added that for wheat beers, the haze should be about the proteins from the wheat and a low flocculating yeast strain.
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Offline jonnym_ch

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Re: refractometer reading for cloudy weizens
« Reply #7 on: March 21, 2019, 02:16:27 PM »
hey again Oginme,
no worries, that was kind of a given. and i have to say i have no issue with rolling the bottle before opening to rouse the yeast with a weizen, however i wanted to experiment with flour to see how it affected the taste and mouthfeel as well as the overall visual aspect.
cheers,
jonny

Offline dtapke

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Re: refractometer reading for cloudy weizens
« Reply #8 on: March 21, 2019, 03:03:14 PM »
I'd love to hear from any respected Professional brewery that adds flour to their beers for cloudiness. I've heard of adding a touch of wheat flour in the BOIL which just seems unnecessary, as you're only gaining the wheat proteins so one could just as easily add wheat to the grain bill for this (and my/many neipas have wheat)

as Oginme stated, any haze should come from the process and ingredients common to beer, not from adding stuff.

as far as refrac readings go, I've found its nearly impossible to tell, I've tried the top of the "line", bottom of the "line", and middle of the "line" it's all a crapshoot. just call it beer and drink it.

again, you do you, Personally i'd never add Rice to beer, but hey, Budweiser does it so it must be good right?
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Offline GigaFemto

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Re: refractometer reading for cloudy weizens
« Reply #9 on: March 21, 2019, 05:34:47 PM »
will a hydrometer react differently to the addition of flour as it surely must change the density of the liquid ?

Yes, adding flour would change the hydrometer reading if the flour is in suspension and does not settle to the bottom with the float riding above it, but if you only added 1 tbsp for 5 gallons I don't think it will have much effect.

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Offline jonnym_ch

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Re: refractometer reading for cloudy weizens
« Reply #10 on: March 23, 2019, 03:27:49 AM »
hey all,

firstly i should correct my earlier statement to state that i actually added the flour at 5mins and not at flameout ... not sure that that changes anything.

dtapke - a google search will show lots of links to articles and forums referencing professional breweries using flour in their beers ... notably in neipa's but also in weizens. is it traditional ? clearly not, but then a large part of the homebrewing revolution has been about people doing un-traditional things with beer so perhaps that's not a bad thing :)

i also only used about a third of the yeast recommended as i have read that stressing the yeast will produce greater quantitiy of esters ... i am totally aware that this beer might go to sh*t but for 30 bucks of material and a pleasant day brewing it's not that much of a risk, and who knows, it might just turn out amazing !

thanks again and happy brewing !

jonny

Offline PeeBee

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Re: refractometer reading for cloudy weizens
« Reply #11 on: March 23, 2019, 04:25:00 AM »
This query backs up a conclusion I'd been reaching, but something I would notice in an "ordinary" fermenting beer:

Towards the end of fermentation with a lot of yeast clouding the beer you do have to make a "best guess" out of the reading because the line is smudged (light is getting scattered by the sample). As time goes on and the beer clears the line starts to sharpen, and my "best guess" readings start to go up. Only by a fraction, but it does suggest that haze and fine suspended particles in the beer does create lower than expected readings.

Needs a geek on the job to properly explain it. Or a "Shrink" to point out I get delusional at times - hang on, I've already got one of them.

Offline Oginme

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Re: refractometer reading for cloudy weizens
« Reply #12 on: March 23, 2019, 06:15:47 AM »

Needs a geek on the job to properly explain it. Or a "Shrink" to point out I get delusional at times - hang on, I've already got one of them.

Alright, challenge accepted! 

A refractometer works by channeling light through a prism.  The prism breaks the light into the various colors and displays one through the lens piece.  When a coating of water is added to the surface of the prism and the diffusing cover closed, the light which comes through splits to allow the blue light to fill the eye piece along a line which separates the blue light from white light.  This creates a line across the round viewing lens of the eye piece.  Now the liquid properties of water are such that it has a refractive index of 1.333, which means that light in a vacuum travels 1.333 times faster than light through water.  The addition of sucrose (or in our case maltose) changes the refractive index in that the sugar molecules slow the light down even more and this difference in speed causes the dividing line of light in the prism to shift, thus moving the line between blue light and white light in the viewing port of the refractometer. 

Now, all the refractometers we use are 'tuned' (the etched scale) to measure sucrose concentrations.  Maltose is very slightly different from sucrose in refractive index, but close enough.  This is one reason you should always measure the Brix or Plato scale on your refractometer and then convert that to gravity.  With low concentrations of sugars in solution, the difference is not great, but it magnifies as the concentration increases.

The presence of haze materials in the solution such as suspended proteins yeast cells and particulate matter, cause a scattering of the light as it passes through the fluid.  This scattering creates a blurring of the distinct line as it is seen through the eye piece.  One reason you may be reading the gravity reading as higher is due to the break of the color from light blue to the darker blue becomes harder to determine.  The intensity of the light which comes through the prism is also diminished as some of the light is scattered back or sideways and does not get channeled through the prism.  This further makes the delineation point of the line harder to determine as the contrast is lower.

At this point, I am open to questions other than 'how the heck do I know all this stuff?'.  The answer to that is that I know far too much about seemingly useless trivia such as this as it is part of my job (at least my paying job) to understand how things work.  I've also worked with refractometers off and on for about 40 years and you can't work with something for that long and not understand some of the principles behind it.
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Offline PeeBee

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Re: refractometer reading for cloudy weizens
« Reply #13 on: March 23, 2019, 07:50:03 AM »
Alright, challenge accepted!  ...
Okay, okay; geek credentials convincingly confirmed. You can make everyone totally convinced by suggesting you read that stuff to your goats.

So the "low readings" are probably down to how people interpret the "fussy line" not some scientific reason haze really does skew the reading. So in my case of not too much opaqueness and judging the "middle" of the fuzzy line I'm rewarded with a misreading of about 0.2 BRIX, whereas "jonnym_ch" who must be experiencing a very fussy line with all that flour is experiencing a misreading of up to 1 BRIX because he's judging the line to be ... go on Johnny, tell us ...
« Last Edit: March 23, 2019, 07:53:24 AM by PeeBee »

Offline jonnym_ch

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Re: refractometer reading for cloudy weizens
« Reply #14 on: March 25, 2019, 12:56:42 PM »
hey peebee, hey oginme,
firstly, a mea culpa.
so to explain, i have my equipment profile set so that it takes into account a dilution addition of 20l or water to bring my brewday up from 35l to 55l. unfortunately, in beersmith, the system shows you what the pre-boil gravity should be but then shows the og taking into account the 20l water addition. so you have to make a calculation back to find what the gravity would be prior to the water addition, then make a secondary calclutation to take into account the wort correction to get the brix calculation ... i believe the geek term for this is PEBKAC, which our geek friend oginme will be able to confirm :)
though i still have issues with the reading from my refractometer that i can't explain, even given oginme's excellent explanation.
the two attached photos were taken today just prior to starting the boil. the first reading was taken after mixing up the wort (and dredging up the muck from the bottom) and clearly reads 17brix. the second reading was taken 1 minute later, after i had properly cleaned and dried the refractometer, and as can be clearly seen, the reading is now 18 brix.
and the lines are not blurred so my reading of the results is not an issue ...
is there anything else that can explain why this would happen ?
cheers all ... now i'm going for a beer !
jonny
p.s. peebee, good to see the therapy is working :)