Anyone used ascorbic acid to treat h2s?

I used reduless twice on a wine w h2s and it helped but there is still noticeable burnt rubber smell. I was looking at using a combination of ascorbic acid and the reduless to treat the wine. Anyone have any experience with ascorbic acid? How is it used and does it leave any taste in the wine?

Curious: Because Hydrogen sulfide reacts with alcohols to form thiols, an important class of organosulfur compounds such as sulfur drugs and penicillin.

Sulfa drugs and penicillin both contain sulfur, but neither are thiols.

I have used the combination and it did the trick for me on a slightly stinky strawberry wine that got abused.

I have and do advocate its use..

That "burnt rubber" smell is in all likelihood mecaptans.

Mercaptans are compounds that form when H2S becomes "bonded" into the wine. The problem is that mercaptans can not be treated with copper. You need to take the step of converting the mercapans back into H2S before you treat with copper. Ascorbic acid does this handsomely.

Now, here are the steps you should take...

1) VERIFY THAT THIS IS THE PROBLEM WITH YOUR WINE!!! In other words, before you treat your wine on masse, do a bench trial of say 100ml of wine first. add an appropriate dose of ascorbic acid, stir and let sit for say, 30 minutes. Now add some copper (copper sulfate, a buffed penny, or reduless) stir and wait another 30 min or so.

Now compare the treated wine with wine that was not treated. If it is greatly improved, then you are good to treat your bulk wine.

2) Treatment:

Mercaptans: Incredibly low concentrations (say 3 ppm) can knock you off your feet so just a little ascorbic acid can go a long way (up to 30 ppm). My advice is to go with 10 ppm to start with. You can always treat your wine a second time if need be.

One thing to keep in mind is this.. Ascorbic acid will affect your wines PH and TA levels. Be prepared that your wine may taste a little "sharper" after use.

Add the appropriate amount of ascorbic acid to your wine and stir. Wait 2 days, then treat with reduless. I would recommend that you start with a 10ppm ascorbic treatment first. Here is a treatment table that I have in the past



Standard Treatment

0.04 {grams per gallon for 10 ppm}


Treatment Per Tank

Liters Gallons Dosage (gr)
500 132.086 5.28344
300 79.2516 3.170064
200 52.8344 2.113376

Ascorbic Acid Addition 10 ppm ascorbic acid = 3.8 mL of 1% ascorbic acid in 1 gallon wine

10 ppm ascorbic acid = 0.04 g of ascorbic acid in 1 gallon wine

John, I agree with nearly everything you said, but there are a couple of points I want to make a minor correction to.

Mercaptans and Thiols are the same thing. These are compounds of the form R-SH (where R = any of a number of bases). The simplest thiol is sometimes said to be H2S itself (H-SH), but the simplest one above that is methanethiol (CH3)-SH. These do have an extremely low threshold for detection. However, they can be treated by copper (with no need for ascorbic acid).

If thiols (i.e., mercaptans) are left too long, they can form other compounds that are harder to treat. In particular, they can link up to form disulfides, that is, compounds of the form R-S-S-R. These have a much higher sensory threshold (that is, you need more of them before your wine is ruined), but they are much harder to treat. For these, you need ascorbic acid to reduce them to thiols (i.e., mercaptans), which can then be treated by copper.

Some useful references:


http://en.wikipedia.org/wiki/Thiol
http://en.wikipedia.org/wiki/Disulfide
http://en.wikipedia.org/wiki/Wine_fault
http://www.fruit.cornell.edu/shared/pdfs/SulfurOffOdor.pdf
http://wine.appstate.edu/sites/wine.appstate.edu/files/Chart%20Aromas%20FH_1.pdf
http://www.bcawa.ca/winemaking/flaws.htm
http://www.techniquesinhomewinemaking.com/home%20winemaking%20rotteneggs.html

sour_grapes said:

John, I agree with nearly everything you said, but there are a couple of points I want to make a minor correction to.

Mercaptans and Thiols are the same thing. These are compounds of the form R-SH (where R = any of a number of bases). The simplest thiol is sometimes said to be H2S itself (H-SH), but the simplest one above that is methanethiol (CH3)-SH. These do have an extremely low threshold for detection. However, they can be treated by copper (with no need for ascorbic acid).

If thiols (i.e., mercaptans) are left too long, they can form other compounds that are harder to treat. In particular, they can link up to form disulfides, that is, compounds of the form R-S-S-R. These have a much higher sensory threshold (that is, you need more of them before your wine is ruined), but they are much harder to treat. For these, you need ascorbic acid to reduce them to thiols (i.e., mercaptans), which can then be treated by copper.

Some useful references:


http://en.wikipedia.org/wiki/Thiol
http://en.wikipedia.org/wiki/Disulfide
http://en.wikipedia.org/wiki/Wine_fault
http://www.fruit.cornell.edu/shared/pdfs/SulfurOffOdor.pdf
http://wine.appstate.edu/sites/wine.appstate.edu/files/Chart Aromas FH_1.pdf
http://www.bcawa.ca/winemaking/flaws.htm
http://www.techniquesinhomewinemaking.com/home winemaking rotteneggs.html

Click to expand...

SG...

Sorry for oversimplifying it. Since the OP has already attempted a treatment with reduless, I was really only thinking of disulfides when I wrote that post. Thanks for elaborating!

sour_grapes said:

Sulfa drugs and penicillin both contain sulfur, but neither are thiols.

Click to expand...

Never said they where! Said thiols were organosulfer compound. Sulfur drugs, and penicillin are also organosulfer compounds. Are they not?

My curiosity came from the standpoint of their conversion, and using C to reduce those compounds back to thiols.

Tenbears said:

Never said they where! Said thiols were organosulfer compound. Sulfur drugs, and penicillin are also organosulfer compounds. Are they not?

My curiosity came from the standpoint of their conversion, and using C to reduce those compounds back to thiols.

Click to expand...

Okay, I misread your statement, then. Yes, you are correct, thiols, sulfa drugs, and penicillin are all organosulfur compounds. From the structure of the sentence, I thought the "such as" part referred to thiols, not to organosulfur compounds in general.

sour_grapes said:

Okay, I misread your statement, then. Yes, you are correct, thiols, sulfa drugs, and penicillin are all organosulfur compounds. From the structure of the sentence, I thought the "such as" part referred to thiols, not to organosulfur compounds in general.

Click to expand...

I am not much on English composition, But I could dazzle you with the Lakota language

The important point is that the oxidation state of the sulfur in sulfa drugs is very different than thiols. Thus, they have very different chemical properties.

Hey everyone. So I think I have it. What I have a disulfides. I need to treat w ascorbic acid. Is there a reason to start w 10 rather than 20 ppm? I mean you can't really tell the ascorbic worked until treated w reduless. Since I already treated twice w 15 ppm reduless I would rather only use the reduless one more time. I'm not sure when the reduless becomes harmful but the manufacturer recommends treating a max of twice unless someon out there understands reduless better than me and when it becomes harmful.

So to treat 10 gallons of wine w ascorbic .4 g would be 10 ppm? I will treat w 10 or 20 ppm wait 2 days and treat w reduless. Is this correct?

Also thx everyone for the very useful comments.

Ascorbic acid is very tart. You really do not want to add more than what is needed. I have had to use ascorbic acid in the past and have found that a concentration of 10ppm usually does the trick while only slightly affecting the ph/taste of the wine.


I would do a bench trial to determine what you need. Start with a 10 ppm concentration of ascorbic acid in a 100ml sample. Stir, wait 30 minutes, add your reduless, stir and wait 30 minutes, then check for improvement in the wine.