Is there an easy way to measure sulfite? Thanks to some good advice from Lum, I am going to try MLF. However, I am wondering if I should wait, as I sulfited when I kicked things off. Also, my local wine shop said I could open the carboy to dissipate some of the sulfur, but this sounds risky to me. Any ideas?
Thanks,
Vic
The standard Ripper test is quite easy to do on white wines, but can be difficult to do on reds because the color shift is hard to see.
You need a few chemicals:
0.02N Iodine solution 25% sulfuric acid soluble starch solution (Be sure to boil this if it's been awhile since you used it, or if making fresh.)You also need some glassware:
10ml graduated pipette (disposible is OK) 50ml graduated cylinder (Nalgene is best for this) Reaction vessel (I use a 500ml wide mouth Erlenmeyer flask for this, but you could use almost any clear vessel - e.g., a jelly glass, small Mason jar, even a wine glass.Measure 50ml of wine using the graduated cylinder and dump it into the flask. Add a few drops of the starch solution. Just before titrating add ~10ml of the sulfuric acid to the flask Fill the pipette to the zero mark and add iodine solution to the flask with constant swirling. Watch for the endpoint in the flask, which is a color change to a faint, persistent indigo, going dropwise as you get close. Read the volume of the iodine off the pipette and calculate the free SO2.
ml iodine (0.02 * 20 * 32) = ppm free SO2
It takes a bit of practice to do, but it isn't all that difficult. The only expensive item is the 0.02N iodine solution, which must be kept in a dark place when not being used.
You don't need a 50ml volumetric pipette for measuring the wine or a fancy burette with a stopcock on a ringstand to get good readings with Ripper. Simple tools will get you a number that's plenty good enough for your purposes. Your technique at measuring the volume of iodine required and spotting the endpoint are what's most important.
Tom S
Don't open the carboy.
The Ripper test Tom describes is very commonly used. If you only have one batch or so going you may want to consider buying a box of Titrettes by Chemetrics. Most wine shops supply them, a box of 10 is around $12 US. That's not cheap, but there is no initial investment either. They are actually a reverse Ripper test, if used on reds I usually look at the foam to see when it's color changes; it's easier to spot that the wine, it will change from blue-violet to burgundy-pink.
Joe
Vic Whirlw> Is there an easy way to measure sulfite? Thanks to some good advice from
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