Testing for Residual sugar in a wine

One of my wine making friends was talking about his 2009 Sauvignon Blanc and how it tasted a little sweet. He was wondering about how much residual sugar was left in the wine and if it would be stable in the bottle.

Two wine making sayings came to mind when talking about this topic: If you taste sugar in the wine, there is usually more than 1% there since that is about the normal tasters threshold for sugar, and if you want to re-start a stuck fermentation, just bottle the wine! { wine with residual sugar will very likely ferment in the bottle, that's how sparkling wine is made!}

So it's better to know if the wine has residual sugar before bottling.

If you like the taste of the wine with a little residual sugar you may need to take some steps to make sure the wine does not kick off a fermentation in the bottle. Of course a few bubbles in a Rose is not necessarily a bad thing to happen... but not in a white wine that you are proud of...also a fermentation in the bottle can lead to cloudy wine and off odors.

You cannot use the hydrometer to measure sugar once fermentation is done since the alcohol is lighter than water and that's what the hydrometer is measuring; the specific gravity {SG} of the solution against the SG of water {1.0}. When there is more then 10% alcohol and only a few brix of sugar you can get a negative number reading on the hydrometer.

e.g. 1 brix = .00388 SG. So a wine with 6 brix of sugar will have a SG reading of approx. 1.023 not counting the alcohol!

If we take into account the @ 10% alcohol which has a SG of @ .78 the resulting SG reading should be: ( .88 * 1.023 + .10 * .78 = .9782) a negative number!

One method I use to measure residual sugar is to use a Urine sugar test kit. The kit is very easy to use and will measure sugar in the range : negative sugar up to more than 4%.

I purchased my "kit" years ago. It's called Clinitest Urine sugar test kit. It consists of a small test tube, a eye dropper, reagent tables, and a color chart for reading the results.

I don't think you can buy the kit any longer, but the reagent tablets are still available so you can put together your own kit.

A friend that is a nurse said they {hospitals} don't use the tablets anymore and the reagent tablets are inventory that is being sold off.... Amazon carries them...

Clinitest Reagent Tablets

Add you own test tube and eye dropper and you will be set for measuring residual sugar in your wines.

Note that there are residual sugar testing kits available from wine making supply stores. One kit available is the Accuvin Residual Sugar Test Kit.

One reason I like the urine sugar kit more than the Accuvin kit is that the test strip colors are very bright and easy to read...e.g. they are not all some shade of blue as in the Accuvin kit....

Here's a video of me measuring residual sugar in a few of my wines.

Trial Blending Session

In my last post I wrote about creating "Trial Blends". In that session, I blended my 09 Malvasia Bianca with the 09 Sauvignon Blanc {SB}. A 1 to 1 blend seemed to be on the right track.







In this session, I'm going to throw in my 09 Pinot Grigio {PG} into the mix.





The techniques outlined in the last blog post still apply...e.g. mix small amounts {20-40 ml of wines} in a glass and taste.





One reason to do multiple trail blending sessions is to be able to focus on a subset of wines and combinations to avoid getting hopelessly confused.





For this session I want to see if adding my Pinot Grigio to a blend with the Malvasia and Sauvignon Blanc will yield a better wine than the 1 to 1 Malvasia-SB blend from my last session.





the wines....


PG: light straw yellow, hints of pear fruit in the nose, tart and clean. Slight bitterness in finish.



Malvasia: Nice floral nose, thick in the mouth, tart with fig-like flavors. Very nice.



SB: Grassy nose and flavors with a slightly hot and bitter finish. This sample was pulled from a different carboy than was used for the last blending session. This one does not have the aggressive SB nose like the previous sample!





Note: at some point it is a good idea to blend all containers of the same variety to get a uniform wine, unless a container has something bad or good going on as a reason to keep it separate. Also you won't have to wonder why one bottle tastes different than another later on....

I blended up the favorite blend from my last session, the 1 to 1 Malvasia and SB, to taste the new blends against.

First I tried a 1 to 1 PG and SB:

The PG pear nose comes through and the bitterness of the SB is toned down, but still there. Only OK.

Next I tried a 1 to 1 to 1 PG, Malvasia and SB blend:

The Malvasia adds some floral component to the PG pear nose and the thickness of the Malvasia helps to further smooth out the SB. Very good acid and complex flavors though no variety stands out...e.g. it will be hard to tell what variety you are tasting later on...Very Good blend. I like it better than the 1 to 1 Malvasia and SB.

I tried a few more blends that were dead ends... and finished off the samples with dinner. Woke up this morning with a headache from too much sampling....

I have one more trial blending session planned for later in the month. My fellow home wine making friends will be coming over to taste everyone's 09 wines. I plan to pour my two favorite blends at that time and get everyone's opinions... should be fun!