Help - Sulfur smell in primary. Whte-Muscato

Should we try yeast energizer or aerate and wait to

I'm not sure if my suggestions arre valid or not, and I'll be interested in what others say. Last year I had the same experience with batches of petite sirah, syrah, and zinfandel. I attributed it to poor nutients in the original grapes because otherwise I did exactly what I had been doing with dozens of batches of wine.

The first thing I did was I agitated the must to try to drive off the SO2. I then added extra nutients (the Wine Lab has a product called superfood, which I now add in small amounts to all of my grapes that I'm able to buy here on the east coast.

In each of the batches the smell persisted but to a lesser degree. Finally, when the secondary was completed, I treated with minute (really minute) amounts of CuSO4. This worked beautifully with the petite sirah and the syrah, but the zin was still smelly. At that point, I figured that the zin was a lost cause and into the crapper it went.

What do others think? Do you routinely pre-treat with nutients?

Lee

I do... the grower even told me this year that it was necessary this year. Unless one is dealing top quality fruit I don't know of any reason not to the recommended amount.

In the absence of pH and sulfite-level testing, the normal recommendation is one tablet per gallon (50-60 ppm SO2). Less SO2 is required for low pH (high-acid) grapes, perhaps a bit more for high pH (low-acid) or damaged grapes. But it doesn't appear that you've added excessive SO2, which could contribute to a sulphur odour.

Some yeasts (e.g. Montrachet) can create H2S problems. Côte des Blancs (Epernay 2) is a slow fermenting, low foaming, low alcohol yeast, but I've never heard that it causes H2S problems.

I assume we are talking about a strong rotten-egg smell?

It could be the yeast. It could be excess sulfur on the grape skins at the time of crushing (in which case you would have made the problem worse by adding Campden tablets). It could be nutrients. You could have detected a potential problem (and taken steps to solve it) by testing the sulfite levels before the crush, or before adding Campden tablets, or before pitching yeast. And you should have inquired whether the grapes had already been sulfited, before adding more. However, you didn't, so now what can be done to solve it?

The following is excerpted from Jon Iverson's "Home Winemaking Step by Step":

However, if there is an H2S problem, it is best to correct it earlier than later. If left alone, the H2S will convert to mercaptans, which are much harder to deal with.

If H2S is detected early in fermentation, rack the wine off the lees and pulp immediately, and add a balanced yeast food or diammonium-phosphate (DAP) at the rate of 1/2 tsp. per 5 gallons. This may solve the problem. If the smell returns, rack it a second and a third time, without adding the chemicals. The object of the racking is to discard the stuff on the bottom of the carboy, which contain most of the H2S-generating elements. If H2S is not generated until late in fermentation, the DAP probably won't help, but

As soon as Clinitest confirms that fermentation is complete, the wine should be racked off the lees. If you leave it on the lees, you are inviting the conversion of H2S compounds into mercaptans, so rack and sulfite right after the wine has fallen still (no more effervescence, or air-lock activity), even if the odor has disappeared.

Copper should not be added during fermentation, but it is safe and advisable to add a bit afterwards. Add .15 ml of copper sulfate (1% CuSO4*5H2O) per gallon, which will add .1 ppm of copper. Fining with Sparkaloid at this stage will eliminate more of the impurities. Stopper it and set it in a cool place.

As long as the stopper stays seated, the problem is probably under control. If the stopper starts popping out, the H2S compounds are being converted into mercaptans! Promptly rack again, but this time the wine should be racked into an air-free atmosphere if possible (i.e. displace the air with CO2, argon, or nitrogen, before racking). Add another .15 ml of copper sulfate.

Hopefully, and probably, these three measures will solve the problem.

Hi, Wen I first started making wine, I had a few batches that had that smell. After asking a few questions on this NG and reading articles, I went and bought some DAP ( diammonium sulfate). I now put that in EVERY batch of wine I make, and I am very pleased with the results. I havn't had any sulphur problem in any wine since.