Wild Yeast

[wineview]

Sometimes when I purchase buckets of juice, I can see the fermentation already starting by the time I get home. I am assuming this is from the wild yeast that was present on the skins. Up to now, I would make a starter and pitch my own yeast. Would it make a difference if I killed the wild yeast before pitching my selected strain?

WV

 

[winemaker81]

There's no need to try to kill the wild yeast. If you make a starter with a good commercial yeast, it will crowd out competition.

If you intend MLF, you do NOT want to add K-meta before inoculating with MLF as it may prevent the MLF from happening.

 

[gabe]

We have always killed the wild yeast in our buckets. On the day our juice arrives we open immediately and add 1/4 teaspoon of metabisulphite. They are too cold anyway to pitch your desired yeast. Remove the lid so the gas could escape.
Wait 24/36 hours before you pitch your yeast. If you don’t kill them there is a possibility of the wild yeast to take over the fermentation.

 

[CDrew]

There's no need to try to kill the wild yeast. If you make a starter with a good commercial yeast, it will crowd out competition.

If you intend MLF, you do NOT want to add K-meta before inoculating with MLF as it may prevent the MLF from happening.

There are other reasons to add sulfite at crush-among them to kill the bacteria that are also present in the grapes, especially if there are many shriveled or bird damaged grapes. I usually aim for 30 ppm after crush and the must can sit 24 hours with no evidence of fermentation or spoilage. Supposedly the bacteria are inhibited at lower concentrations than yeast and so 30ppm has proven plenty.

Also, I have never had MLF not complete, regardless of sulfite additions at crush. I think the reason is, most sulfite is bound up within 24 or 48 hours. So by day 3 when I would typically add MLB, and sulfite from crush is long gone.