Smelly Ferment

[Rob S]

I must be missing some details as it seems I'm not doing everything correctly. I often get a smelly ferment, due to some H2S I'm getting the impression. I've spent weeks searching for information that leads me to believe if yeast do this it is because they are stressed due to certain factors that are not ideal for them. I'm meticulous about sanitation, do proper yeast hydration ie Dynastart (follow Morewine's instructions), adjust to start with an acceptable TA and pH, and doing a YAN test to figure out how much nutrient to add to the must at cap formation, and up to one third sugar depletion. Yet it is as if I'm underestimating the amount of nutrients to add? I have a Spanish Tempranillo going right now. YAN was 130 mg per L. I used the kit containing formaldehyde and did a titration using my pH meter. Calculated I needed a total of 350 mg per L. Starting Brix was 23. I adjusted pH to 3.7 with 2 g per liter of tartaric acid as the pH was 4.03. TA increased from about 4 to about 6 (I estimated). Fermentation with D254 yeast started slowly and at cap formation I added about 100 mg pet L of YAN. Fermentaion started to get smelly the next morning. I added half of what was the remaining 100 of YAN. It stopped smelling and smelled nice and fruity (Brix was down to 21). Eight hours later, brix was down to 16 (one third sugar depletion) so I added the remaining 70 YAN. According to this yeast I referred to documentation saying I needed about a total of 350 YAN. Looks like I will have to keep adding more and deal with H2S issues that means a less clean fermentation than would be ideal and possible consequences of a lesser quality wine in the end.
I can't understand how come this issue keeps coming up even though I'm doing YAN tests to target a certain nutrient addition. I use Fermaid O and fermaid K.

Thanks,
Rob

 

[sour_grapes]

Wow, I am not conversant on the required YAN numbers, but it sure seems like you are doing everything correctly... Very rarely do we hear from someone that they have H2S and also that they have done YAN tests!

 

[CDrew]

Yes, the YAN thing is slippery for me too. There isn't enough hard data to know what to do.

My suggestion is to use a yeast that is incapable of making H2S. Avante, Brio, Bravo come to mind. And that's for next year!

Good luck, and I hope you get it cleaned up.

 

[Rob S]

Thanks for your suggestions. Looks like a bit more food than calculated and more often in smaller increments is helping. Like you suggest other yeast alternatives, although that means limiting getting the profiles specific yeasts will give you. It's the overnight where one is not there, or while one is at work.

 

[stickman]

Need more information to help understand what may have happened and to hopefully help prevent future occurrence. I agree that something unusual is going on to get H2S that early in the fermentation process, especially with the work you did up front and using good nutrients etc. Was the must from frozen fruit or did you crush grapes, any sulfite added pre-ferment, temperature of must at yeast pitch, did you add Fermaid O or K at different times or together, how many grams Fermaid O or K did you add, what size batch is this?

 

[1d10t]

I agree that something unusual is going on to get H2S that early in the fermentation process, especially with the work you did up front and using good nutrients etc.

I'm pretty new to wine but I had the same question pop into mind. I wouldn't expect the yeast to get stressed till much later in the process even if no nutrients were added up front. Maybe a small batch with the non H2S producing yeast would be a good test here?