Things You Will Need
- Copper pot scrubber
- PVC pipe
- Graduated cylinder
- Copper sulfide
- 3 glasses
- Absorbic acid powder
- Distilled water
- Food scale
- Plastic or wooden stirrer
Mercaptans are the result of hydrogen sulfide in wine binding with alcohol and oxygen. If hydrogen sulfide is not promptly removed, mono-mercaptans (sulfides) can form as early as two days after fermentation.
These mono-mercaptans are loosely bound to the alcohol in the wine and are easy to remove with the help of a little copper. Poly-mercaptans (disulfides) form later in the aging process and become the dominant sulfide in the wine after roughly two months.
These poly-mercaptans bond to both the alcohol and the oxygen in the wine and are much harder to remove.
Remove Mono-Mercaptans (Sulfides)
- Insert a clean, pure copper pot scrubber 1-inch deep into a sections of 1-inch clean, plastic PVC piping. For the copper pot scrubber, the British Columbia Amateur Winemakers Association recommends using the Molly Maid brand.
- Pour the wine through the pipe. The mercaptans will bind with the copper and filter out of the wine.
- Smell the filtered wine. If any of the odor remains, filter it a second time. If the odor still remains, move on to the second section.
Remove Poly-Mercaptans (Disulfides)
- Dissolve 4.1 grams of copper sulfate in 10 ml of distilled water. Stir well until the copper sulfate is dissolved. Add 90 ml of distilled water to the solution. Use this copper solution to test the wine in step two.
- Fill each of three glasses with 100 ml of wine. Add 0.05 ml of copper solution into the first, 0.1 ml to the second and 1.5 ml to the third. Stir each glass well with a plastic or wooden stirrer. Smell each glass. The one without a mercaptan odor has the right amount of copper solution in it. If all of the glasses still smell, fill three more glasses with 100 ml of wine each. Then mix 2 ml in the first, 2.5 ml in the second and 3 ml in the third. Repeat the smell test. Continue adding increasing amounts of copper solution (.5 ml more each time) until you find the right amount and the smell is dissipated. Record the correct amount of copper solution so you don't forget it.
- Add 0.025 grams of absorbic acid powder per liter to the entire supply of affected wine and shake or stir well.
- Stir well, and allow the wine to sit for at least 24 hours.
- Multiply the number of milliliters you recorded in Step 1 by the number of liters of affected wine you need to treat to discover the amount of copper sulfate you must add to the entire supply. For example, if you needed 0.1 ml of the copper solution to dissipate the smell in a 100 ml glass, and you have 20 liters of affected wine, you will need 2 ml of copper sulfate to remove the mercaptans in the entire supply (0.1 times 20). Add the required amount of copper sulfate to the container and shake or stir well. The smell will take several days to dissipate.
Montrachet (UCD 522) and certain strains of Steinberg yeast produce high amounts of hydrogen sulfide. The copper scrubber must be new and fresh out of the packaging. Excess handling will reduce the efficiency of the copper scrubber. Mono-mercaptans or sulfides smell like skunk, garlic, cabbage, onion or rubber. Poly-Mercaptans often smell like asparagus, corn or molasses.