testing sulfite levels

[tonyt]

I have noticed that some of y'all test sulfite levels rather than add automatically every three months. What gadgets are needed and what guidelines do you use to add K-Meta? Or is it more trouble and expensive than it is helpful?

 

[ibglowin]

I am finding that mine are not dropping significantly every 90 days (YMMV) and that on some of my early wines where I added every 90 days regardless I can smell the sulfite when I first open the bottle. This usually goes away with some air time but I don't want that smell.

I invested in an Aeration/Oxidation rig several months ago for more accurate testing of free sulfite levels in my wine. There is a chart that will tell you how much sulfite you need for a red or white at a specific pH. It varies with pH so you need to know both.

I had problems with the Accuvin test. They all looked the same color to me. They are an inexpensive and fairly accurate way to test for free sulfites. I think whites are easier to see the color change than a red.

Here is the thread I started on my Aeration/Oxidation Rig

 

[tonyt]

Yes, I must have read that a while back. Not being a chemist perhaps the AccuVin will be where I should start. Would I add sulfite every three months and then test prior to bottling? I assume the chart tells how much to add at bottling? http://www.finevinewines.com/p-358-301-10.aspx And yes it is that first opening the bottle smell that I hate till it eventually dissipates.

 

[ibglowin]

Accuvin is a good place to start for sure. They are easy to use as well.

I found a simple Sulfite levels vs pH chart.

You can see how pH effect the required amount of Sulfite to protect the wine. As pH levels go down (more acidic) the level of Sulfite required to protect the wine also goes down.

If you add your package of sulfite when you stabilize and fine you should check the level of sulfites every 90 days (just a few times to see where your levels are ending up) and then add accordingly to the appropriate levels based on wine type.

You may find that you don't require a full 1/4 tsp and perhaps get by with 1/8 tsp every 90 days.

Hope this helps!

 

[Wade E]

I started using the 4 month schedule years ago.

 

[Bacci]

Wade,
After realizing that adding 4.8 grams of Sulphite at stabilizing phase on kits is adding about 120 ml of SO2. After 28 day clearing period, could you skipthe 1/4 tsp KMET addition at the timeyou rack and startbulk aging? Iwould normally bulk age 90 days before racking again or bottling andcouldadd 1/4 tsp KMET then. If my backend formula is right, 4.8 grams equates to about 120 ml of SO2.Seems like a lot

 

[Bacci]

I meant 120 ppm. 4.8 grams is about the equivalent to 11 campden tablets.I don't do accuvin testing, just trying to avoid over-sulfiting since I'm detecting after adding 1/4 tsp for bulk aging/bottling. The kit companies mustreally insure againstoxidation or bacteria at all cost or the clearing phase blows throught free SO2.Can anyone sharetested SO2 results after clearing stage, before racking to bulk age or bottling?

 

[ibglowin]

I will through this out there. I did the 1/4 tsp every 90 days for the first year before I started testing first with Accuvin and now with an A/O rig. Every single wine I made has a nice Sulfite bouquet when opened and requires an hour decant to get it down to where you can actually smell the wine instead of Sulfite.

My last wine (a Red) I had only added the packet at stabilization and 1/4 tsp in an 8 mo bulk aging period still had 31ppm free SO2 in it.

Now perhaps because I work with Sulfite on a semi daily basis I can smell it at low levels and others may not notice it but, this wine had plenty of free SO2 in it and it probably should have had at least one and perhaps 2 additions more added if I had followed the general rule of addition while bulk aging.

So where am I headed with this, I am headed to only adding the packet of Sulfite at stabilization and no more with bottling between 6-8 months of bulk aging.

I will of course test just before bottling and add more if necessary based on the level found, the type of wine and the pH of the wine.

I also keep my bulk aging Carboys "stoppered" in the Winter and only have airlocks in the warmer months when the carboys expand more due to increased temps in the winery.

 

[AlFulchino]

good information Mike

 

[ibglowin]

Man that number seems high. For some reason I am thinking it should be less than that. I will see if I can find a chart somewhere to confirm.

Wade,
After realizing that adding 4.8 grams of Sulphite at stabilizing phase on kits is adding about 120 ml of SO2.

 

[ibglowin]

I see what I was missing.

The assumption is when you add the 4.8gms of Sulfite you do not end up with a 120ppm free SO2 in the wine. Only approx 57% becomes available, the rest is consumed pretty much instantaneously (reacted with) and is therefore not available to protect the wine anymore.

So that initial dose ends you up with an aprox 68 ppm of free SO2 to start with and then of course starts to drop from there with more and more exposure to O2.

 

[Bacci]

my formula for coming up with the 120 ppm, is using formula in winemakers answer book.6gals.x 3.785 x(adding 120 free SO2 mg/L) / (1000) x (0.57)
22.71 x 120= 27252/570= 4.78 grams


I'm not a chemist, does this formula already take into account for the % for free SO2?


Even so,racking off the lees after 2 -3 weeks of first Sulphite addition (4.8g) and thenadding another 1/4 tsp. I get the same sulferbouquet.This appliesmostly tomy last RJS-WS kit, but my CC kits only suggest adding 1/8 tsp. didn't notice the gram content on their packets and don't seem to be quite as strong SO2. Guess I'm not going to rest until I get a Accuvin kit.

 

[ibglowin]

I was looking at the handy dandy sulfite calculator from Winemaker Magazine

That calculator assumes that only 57% of the sulfite actually becomes free SO2 to protect the wine, the rest gets bound up immediately and unavailable to protect the wine thus the over addition.

As the pH in a wine drops, more and more SO2 will remain free in solution. At a very low wine pH of 3.1, only 25% will be bound, and 75% will remain free. At a pH of 3.5, 50% will be bound and 50% will remain free.

 

[Randoneur]

Does temperature make a difference, i.e. do you need to add more kmeta if you are aging in the summer vs. the winter? I'm quessing that it makes a big difference.

 

[ibglowin]

I would say no, the amount of sulfite required is based on the amount the wine is exposed to air (O2) which should be a constant regardless of time of year!