Citric acid spot on ML chromatography

[Cap Puncher]

So, I started a old vine zinfandel from fresh grapes back in October. ML bubbles have stopped ( probably a month ago. I think ML is complete and the spots visable are citric acid. I have another ML chromatography from a month ago that shows 2 of the zin carboys with what I think are malic spots, but I didn’t include the standard. I typically don’t see citric acid marks. I have a petite sirah that I started in February on the chromatography as well. It is hard to find chromatography examples with citric acid on them. My understanding is that citric acid does show up just below malic acid on chromatography. Also, I did not use any citric acid on the must. I just want to confirm so I don’t sulfite too early. Thoughts?

 

[Denden5136]

I would really like to see the control for the chromatograpy to confirm that it is citric acid. Citric acid does exist in small amounts in wine. Normally O. oeni will consume citric acid when it completes consumption of malic acid, so if you did MLF, it should clear up the citric acid as well. When consuming citric acid, MLB can break it down to acetic acid, but normally it is in very small amounts and is unnoticeable.
Can you run another test with the controls just to confirm?

 

[Cap Puncher]

I can’t find a citric acid standard but could probably make one myself. Your right, that is the only way to probably confirm. As much as I don’t want to run chromatography again, I should. It’ll be a fun experiment anyway.

 

[BarrelMonkey]

I recently ran a chromatogram with malic, lactic, tartaric and citric acid standards. You're correct, citric runs a bit below malic.

I made my standard from citric acid purchased at the grocery store...

 

[Cap Puncher]

@BarrelMonkey , in your opinion, do my chromatography sheet seem like citric acid to you? After looking at your chromatography, it definitely seems like mine is only citric acid.

 

[BarrelMonkey]

Citric looks plausible to me... and some strains of malo bacteria have 'late' citric degradation, which might be why you still see some residual spots. But I'm really no expert in this, and so don't take my opinion as the last word...

 

[Cap Puncher]

Citric looks plausible to me... and some strains of malo bacteria have 'late' citric degradation, which might be why you still see some residual spots. But I'm really no expert in this, and so don't take my opinion as the last word...

Honestly, it is all making more sense. I did use VP41, which like Omega that you used, has slow/very delayed degradation of citric acid. Also, the Zinfandel I’m doing, is pretty high alcohol. Probably, 15%+, which is probably delaying the citric acid degradation even more sense it is an unfavorable Environment. Thanks for the insight!