PDA

View Full Version : Post Fermentation Temp & Residual Sugar %



davewaldo
12-23-2008, 03:10 AM
Hi Everyone! I've been reading a lot on this forum for weeks and doing many searches.

I started my first 1 gallon batch of Mead a few weeks ago and everything is going swell! I've been brewing beer for a while and now I've been bitten by the Mead making bug ;D

I live in Australia where temperatures are problematic for fermentation. Because of this I use a modified fridge to keep my Carboys at the desired temps (usually 18 degrees C).

My current Mead has been fermenting for 3 weeks. And is going well. The OG was 1.120 and has dropped to 1.055 and is still bubbling a few times a minute. I'm using US56 Ale Yeast and I expect it to stop around 1.025.

My full recipe and procedure can be found here: http://www.davidwalden.com.au/mead1.htm

My two questions are:

1. Can I remove the carboy from the fridge once fermentation is complete? Will it harm the mead if it ages at around 26 degrees Celsius? Or will it just age faster?

2. Once fermentation is complete, how can I work out the residual sugar content?

Thanks everyone!

Dave.

WRATHWILDE
12-23-2008, 08:10 AM
See This Thread (http://www.gotmead.com/forum/showthread.php?t=13442&highlight=wine+aging)

Cheers,
Wrathwilde

davewaldo
12-23-2008, 07:34 PM
Thanks Wrathwilde, thats some great info!

Can anyone tell me how to estimate residual sugar percentage?

Vino
12-26-2008, 12:31 PM
Can anyone tell me how to estimate residual sugar percentage?

If you measure in Brix (Degrees) you have the answer.

Example:
4 Brix = 4% Residual sugar = 40 grams/liter, 1 Brix = 1% Residual sugar = 10 gram/liter.

If you are measure SG on a hydrometer you can convert to Brix:

Brix can be approximated as 261.3*(1 - 1/g), where g is the specific gravity of the solution at 20°C (68F).

Example:
1.016 SG = 261.3*(1-1/1.016) = 4 Brix

I believe these should get you close.

osluder
12-26-2008, 02:02 PM
4 Brix = 4% Residual sugar = 4 grams/liter, 1 Brix = 1% Residual sugar = 1 gram/liter.

It doesn't affect your point, but as regards Brix you may be off by a decimal point: I believe Degrees Brix (°Bx) is measured as grams of sugar per 100 grams of solution, i.e., it's a dissolved sugar-to-water mass ratio.

Vino
12-26-2008, 03:16 PM
you may be off by a decimal point.

Duly noted (and corrected)!

osluder, Can I assume by your avatar you are a SRV fan?

osluder
12-26-2008, 03:34 PM
Can I assume by your avatar you are a SRV fan?

Indeed, you may so assume. ;D (And his older brother Jimmie's tribute song Six Strings Down still chokes me up 18 years later. :()

Vino
12-26-2008, 03:41 PM
I was fortunate enough to see him perform at the Fox Theatre in Atlanta in 1985...without a doubt the Greatest Electric Blues guitarist to ever live.

osluder
12-26-2008, 04:24 PM
...without a doubt the Greatest Electric Blues guitarist to ever live.

Absolutely no argument from me, but maybe we shouldn't start a "guitar hero" flame war. ;D From the first time I saw him in maybe 1978 as part of the Triple Threat Revue (with Lou Ann Barton and WC Clark), until my last show when he headlined La Semana Alegre in April 1990, I was a huge fan. Stevie Ray recorded was great, Stevie Ray live was transcendent and I tried to see him every chance I could, so maybe two dozen shows over 12 years. The way he evolved over that time was amazing to witness: from drug-fueled intensity to sober, technical mastery. Just incredible. The DVD Live at the El Mocambo (c. mid-1983) is must seeing for the uninitiated. Serious Jimi Hendrix channeling at many, many points.

And just to bring this post sort-of back on topic ... :)

Here are some values I came across for the various Champagne sweetness designations:


Brut Natural or Brut Zéro (less than 3 grams of sugar per liter)
Extra Brut (less than 6 grams of sugar per liter)
Brut (less than 15 grams of sugar per liter)
Extra Sec or Extra Dry (12 to 20 grams of sugar per liter)
Sec (17 to 35 grams of sugar per liter)
Demi-Sec (33 to 50 grams of sugar per liter)
Doux (more than 50 grams of sugar per liter)

[Retrieved from <http://en.wikipedia.org/wiki/Champagne_(wine)#Sweetness> on 2008-12-26]

These are described in the text as "[t]he amount of sugar (dosage) added after the second fermentation".

-- Olen

Medsen Fey
12-26-2008, 04:25 PM
2. Once fermentation is complete, how can I work out the residual sugar content?


The measurement of the remaining gravity gives a good estimate, but it may not be exact, and may vary based on the alcohol content. An 18% ABV solution with a residual gravity of 1.000 has a lot more sugar in it than a 10% ABV solution with a gravity of 1.000.

You can use Clinitest tablets (http://www.utmb.edu/poc/SOP/ARCHIVE/2003/MS%20WORD/Clinitest%20Urine2-03.doc)such as diabetics use to measure sugars in the urine. I believe they only go up to about 2% so you may have to dilute your sample to get a reading if it is higher than that. Still, it is pretty quick and easy.

Medsen

Vino
12-26-2008, 04:58 PM
The measurement of the remaining gravity gives a good estimate, but it may not be exact

So what would be considered an industry standard for measuring residual sugar? Or is close the norm?

davewaldo
12-27-2008, 08:38 AM
Thankyou everyone! :)

Thanks Vino, that will get me close enough for what I need.

Medsen, It sounds like there could be (or should be) a formula to closely estimate residual sugar taking alcohol content into account.

Does anyone know if such a formula or graph exists?

Perhaps if one was to use a calculator (like this one: http://www.realbeer.com/hops/kcalc_js.html) to find out Real Gravity as apposed to apparent gravity shown by a hydrometer; then use this reading to determain residual sugar? Finding the Real Gravity would take the alcohol content into account.

Would this work?

osluder
12-27-2008, 02:29 PM
It sounds like there could be (or should be) a formula to closely estimate residual sugar taking alcohol content into account.

Does anyone know if such a formula or graph exists?

ProMash (http://www.promash.com/) has a utility to calculate several parameters including "residual extract" based on apparent Degrees Brix and specific gravity (screen capture below). I suspect something like [Holle 2003] may have the underlying formulas. Perhaps someone knows of a similar text oriented more towards wines?

References

[Holle 2003] Holle, S.R. 2003. A Handbook of Basic Brewing Calculations. Master Brewers Association of the Americas. ISBN 0-9718255-1-3.

Vino
12-30-2008, 12:08 PM
As Medsen mentioned earlier alcohol % and residual sugar levels both affect the SG readings, and so any calculations made using an SG reading only would at best be close approximations.

Accuvin makes a test kit designed to measure residual sugar in wines. It removes the usual interferences from colored and turbid samples which can affect other testing methods (I’m not sure if the Clinitest tablets do the same).

Accuvin only measures the fermentable sugars (Glucose and Fructose) and is designed to measure below 2 grams/liter, but can be diluted using their quick dilute tubes for RS values as high as 40grams/liter.

I have not personally used the Accuvin test kit, since I am happy with getting close, and usually rely on taste.

I have also read about a procedure in which you boil a sample to drive off the alcohol, and then measure the RS, but it seemed quite complicated and I have no intentions of ever “boiling my meads” ;)

Oskaar
12-30-2008, 12:27 PM
I use the Ames clinitest as well. This has been recommended to me by serveral winemakers, as well as the folks from Scott Labs and by good old Clayton Cone himself.

osluder
12-30-2008, 03:20 PM
[The Ames Clinitest] has been recommended to me by serveral winemakers, ...

And it's even good for potato juice (http://www.springerlink.com/content/h2228503085k677u/). ;D A question on the vendor though: Is it now a Bayer product?

I came across this series of posts (http://www.brewinfo.org/articles/clinitest.html) related to Clinitest's use with beermaking. Is it safe to assume this debate does not apply to most meads due to the difference in sugar content of must versus wort? If so, would braggot be an obvious exception?

Medsen Fey
01-01-2009, 10:32 AM
Another potential for error with the Clinitest is the fact that meads may have other things that will react with the copper other than sugar - H2S as an example.

If you've got a few hundred bucks to spare, I bet one of THESE (http://www.cynmar.com/item_detail.aspx?ItemCode=HAW98030) would be handy.