H 2 S CORRECTION

AVOIDING H2S!

Growers dust their grapes with sulfur to retard mildew conditions. You can easily develop H2S, Hydrogen Sulfide, rotten egg off odors, in your wines. Additionally, late season grapes are nutrient deficient, leading to more H2S formation. The trick is to detect early, treat and then remove before these odors progress to more offensive forms.

ADD NUTRIENT AT CRUSH. Use Super-Super Food or DAP.

LET WHITES SETTLE, rack and add nutrient before ferment.

ADD NUTRIENT WITH ML ADDITION. Use Leucofood

or Super-Super Food.

Add the balance of super-super food (not dap)

every day OR EVERY 4° BRIX DROP, until 5º Brix.

More nutrient is useless to the yeast after reaching 5º Brix.

IF H2S IS STILL SMELLED AFTER PRESSING REDS OR THE END OF FERMENTION FOR WHITES, rack and splash vigorously. DO THIS ONLY while still GASSING & NEVER PAST 0° BRIX. Repeat every 6 hours until all sediment is gone and no H2S is detected.

DO NOT AEREATE AFTER FERMENT ENDS! If off odors persist, treat for Mercaptans (See below).

MERCAPTANS: Any odor other than pure rotten eggs (H2S) can be assumed to be mercaptans which will only progress to Di-Mercaptans when areated. If you smell mercaptans (garlicky), assume and also treat for di-mercaptans (burnt rubber).

Just because you aerated and the mercaptan

stinkies went away, IS NOT proof

that they won't come back!

Inadequate removal OF ALL MERCAPTANS will

result in the re-appearence of the stinkies and regeneration of mercaptans to dimercaptans somewhere down the line.

Guaranteed!

Treat early and treat thoroughly.

It's best to do this while the wine is just finishing gassing and is still full of trapped gas. Then you need only treat for mono-mercatans, using copper and carbon. Waiting beyond this time, especially with inadequate SO2, will permit the oxidative formation of di-mercaptans and will require the use of ascorbic acid SO2, as well as copper and carbon.

If you've got really heavy stinkies, you need to start with heavier treatments.

It's best to test small samples first to determine the treatment needed.

Treat heavily enough to remove all traces of the stinkies. Do not guess at the amounts of copper needed. Add only enough to remove the mercaptans....but add enough to get them all completely out.

If your wine still does not smell like pure fruit,

you've still got the stinkies!

H 2 S TREATMENT

Hydrogen Sulfide (H2S) smells like rotten eggs/sulfury/burnt matches.

It happens easily and is also easy to correct --- if taken care of before the end of fermentation.

H2S at the start of ferment usually comes from sulfur sprays used in the vineyard against mildew and bunch rot. For whites, the treatment is to let the juice cold settle, discarding the sediment, before fermentation.

H2S at mid-late ferment usually is due to nutrient deficient musts. The treatment is the addition of an amino acid source like Super-Super Food (not DAP). It helps to add at the start of ferment if you suspect the must might be deficient. Then add every 4°B.

If H2S remains near the end of ferment/pressing, immediately rack off of any grapey sediments that may contain the offending sulfur. Vigorous aeration, at this time only, while ferment is still happening, helps to drive off the volatile smells. Rack and aerate every 6 hours until odors and grapey sediments are gone.

However, if any mercaptans (usually a garlic-like scent) are already formed from the H2S, areation will drive the reaction to the bound

di-mercaptan form (asparagras, artichoke, kerosene, rubber, etc.).

Treatment of di-mercaptans and mercaptans:

STEP #1- Raise SO2 level to the recommended amount, relative to your pH.

STEP #2- Treat for Di-mercaptans:

(3.75 mls of 1% Ascorbic Acid/gallon = 10 ppm ascorbic/gallon)

Start with 30 ppm of 1% Ascorbic Acid solution (11.25 mls/gal.).

Wait 7 days and then do the mercaptan treatment.

Ascorbic additions will confuse SO2 tests by the same

number of ppms.

Step #2- Treat for Mercaptans:

(.15 mls of 1% Copper Sulfate solution/gallon = .1 ppm copper)

Start with .3 ppm of 1% Copper Sulfate solution (.45 mls/gal.).

If, after the above treatments, Mercaptans persist,

you will have to repeat the treatments.

.2 ppm un-bound copper is the legal limit. Too much

can be toxic and can cause a metallic taste and a distinct haze. So, do not overtreat, but do treat enough to completely remove the offending odors/flavors

Step #3- Add Deoderizing Carbon (Norit D-10):

Without following an ascorbic/copper treatment for mercaptans with a small amount of deoderizing carbon, treatment will be ineffective in removing the disulfide off-odors.

Dosage: .02 oz to .08 oz. per 5 gallons. (That's 1/4 tsp. to 1 tsp. per 5 gallons) Too much can strip color.

Simply mix throughout the wine. Be gentle, avoiding oxidation.

The carbon will settle out in a few days to weeks, often clinging

to the sides of the container.