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frustrated by sulfite titrettes

I seem to be having trouble getting accurate readings with sulfite titrettes (Chemetrics in the blue box). I have several batches of wine, mostly finished their primary fermentations, that were made either from fresh grapes (Central Valley grapes brought in to Maryland), or from frozen buckets from Brehm. These grapes were supposedly not treated with sulfite, but my titrations give me values ranging from 20 ppm to 35 ppm.

The only realistic correlation that I seem to get is that if I add sufite, the values on my titrations go up. That's about it.

So, is there any way to get more accurate readings? Can these sulfite titrettes be "calibrated"? Or is it likely that the grapes actually have sulfite from the vineyards?

Lee

Reply to
LG1111
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I forgot to mention...these are all red grapes.

Lee

Reply to
LG1111

See sections 14.3-14.5 of

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HTH,

Ben

Reply to
Ben Rotter

GREAT WRITE-UP!!! Ben, I can't thank you enough. To others reading this, look at Ben's whole website titled Improved Winemaking...it's really instructive.

Lee

Reply to
LG1111

Ben, I just read your article on MLF which I found to be equally helpful. Can I ask you an additional question.

I've just finished the primary fermentation on a batch of what I intend to be a Chateauneuf-du-pape blend of 1/3 syrah, 1/3 grenache, 1/3 mourvedre, and a splash of voignier. I'm not sure whether or not to innoculate for an MLF. the wine hasn't been sulfited yet, and it's light with a nice fruity aroma. Would you do an MLF on this type of wine?

Thanks,

Lee

Reply to
LG1111

I thought Brehm added sulfites to his grapes. Check the labels...

--Lee

Reply to
lee-dont

Whatever sulfite went into the grapes before fermentation is gone by the end of fermentation, but yeasts will produce some small amounts of SO2. Plus titrets generally overestimate by at least 10ppm - but I'm sure all that is in Ben's article...

I've recently started using the Vinoferm kit for measuring SO2 - it seems to be giving better results (and it's cheaper if testing is done on a regular basis). The only issue is that the reagent (iodine) has to be replaced in 1/2 year or so.

Pp

Reply to
pp

Lee,

Thanks for the positive feedback.

Chateauneuf du Pape (or blends made of varieties used in this AOC) are typically put through MLF. Largely, this is a stability issue - a controlled MLF just ensures you don't get a wild one later (possibly in bottle) etc. What's the pH and TA like on this wine? If you really like the way the wine is now, you could just not put it through MLF, retain that fruity aroma, and ensure stability through another method (filtration, lysozyme).

HTH,

Ben

Reply to
Ben Rotter

Is it possible that sulfur spray on the grapes is what you are reading?

Reply to
Sarge

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