Some H2S early into fermentation

[Rob_S]

Hi Folks,

Noticed a bit of H2S 24 hours into fermentation of Frontenac, Marquette, St-Croix blend. Can't seem to find anything when Googling on how much Opti-Red to add to help with issue.

Did add some Opti-Red at very beginning at the recommended rate of 0.3 grams/Litre, so not sure if adding any more would help or would be a good idea?

Using CSM yeast and it is know for having more issues with H2S since it has a high N demand. Did usual procedure for the yeast starter using Dynastart, and added 1/2 of the Nutristart at beginning and the other half of it at 1/3 of sugar depletion. Paid attention to difference in temp between starter and must.

I've fermented the same Frontenac blend in the past and Cabernet Sauvignon without any issues with H2S with this yeast, but did have at one time a huge issue with a Merlot with the same yeast.

Punch the cap 3 times a day.

Thinking might have added the fermentation lock a bit too early, the fermentation is progressing very fast and sugar depletion is going fast, temp of must is 77F, but thinking perhaps the yeast still needs to be under oxygen a little longer and this might help with H2S issue? Could try removing lock for a day and put it back on at 72 hours into fermentation, any advice please?

Thanks,

Rob

 

[Boatboy24]

You don't need Opti-Red. I'm thinking you need nutrient. I'm not familiar with Nutristart - usually go with Fermaid-O. Sounds like your nutrient regimen is OK, but you might try giving it a little more.

 

[stickman]

How large is this fermenting batch? Were the grapes sprayed with sulfur based fungicides right before harvest? What is the current brix or sg? When punching down, be sure to get the yeast at the bottom of the tank suspended. I agree with Jim that you may need additional nutrient. Try a quick bench trial to see if additional nutrients will help; pull a sample and divide between two containers, add a pinch of nutrient to one and swirl both containers and cover loosely. Wait a half an hour and check for H2S comparing the treated vs. untreated.

 

[Rob_S]

Thanks for confirming Opti-Red not for this purpose but keep seeing it come up as such here and there on the web.

Batch is 15 litres. DId not measure Brix this morning but reached 1/3 sugar depletion last night, so past 8-10 brix drop now. I didn't spray them with sulphur, did with Captan and nothing else about two months before harvest. Have been bringing up the sediment while punching down. Ok will do bench trials sounds great. Will add a bit more nutrition, but will avoid DAP since don't want any left over at the end, and DAP is like candy to the yeast, figure better with quality food.
Hoping can get the H2S issue over before mid way through fermentation, so to reduce chance it taints wine.

Not saying this will happen, but hate to reach point where nothing else works and have to resort to CuSO4 like did with a Merlot few years back. It got rid of the H2S and its derivatives, but wine was not very good and not surprising given the yeasts had less than optimal conditions.

 

[stickman]

If the batch is not yet at 10 brix, I would not hesitate to add 6g of DAP in addition to half of the second dose of Nutristart now, and add the remainder of the Nutristart at 10 brix. Given H2S so early in the fermentation, it is likely the must was very nutrient deficient.

 

[Rob_S]

Hi All, Thanks for your tips and it worked. I'm happy to say yesterday I resolved the H2S issue. I left the fermentation lock off for 6 hours and stirred vigorously every 2 hours during that period while adding small amounts of DAP and Nutristart, added 1.2g of DAP and a 1.2 g of Nutristart, and later about half the amounts of each. This morning when I checked there was no H2S odor.

Rob