Interesting Fermentation - Opinions?

Good morning. At the facility where I make my wines, they brought in a small amount of Toreldego for another client. Numbers were run pre-fermentation and the wine showed a YAN of over 600- but a pH of 4.3 and a VA level already above .115.

The fermentation kicked off well, though started smelling like balsamic vinegar, and stuck at about 12 brix. Another test was done and there was still a ton of YAN left - over 350 or so.

The question - do you think the high pH and/or VA could have helped ‘stick’ this fermentation? Curious to hear your opinions . . .

Cheers!

I have no idea what happened here, but I am seeing some things this year that I have never seen before. Low conversion rates, disappearing malics, etc – weird

With high pH and acetobacter already well established, and high YAN, maybe the bad bugs overwhelmed and inhibited the yeast.

At pH 4.3, SO2 would need to be >120ppm to even get 0.4 molecular.

I’ve seen high VA inhibit fermentation from finishing on several occasions so that would be my guess.

+1 VA

Larry, was a malic acid test run on the juice? I’m wondering if lactobacillus ate all the malate pre-fermentation, then started producing acetic acid from the glu/fru. I agree that the VA inhibited the yeast from finishing the fermentation. The good news is that high VA, high RS, interesting grape varieties are very trendy here. You should be able to sell that to any number of wine bars in SF. Just say it’s from an organic vineyard and you made it naturally.

Ed Kurtzman, Wine Yoda

I’d probably go with the high VA hypothesis, but another one occurs to me – in the absence of good temp control, the super high pH and YAN sounds like a recipe for the initial fermentation stage to go so fast that the yeast killed themselves by producing alc inside the cells faster than they could excrete it.