Advise needed on fixing my naturally fermented wine 2021

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sjjan

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Update on the wine produced last fall where I did ferment all naturally, even the grapes bought from Italy from unknown vineyards. So, we are now in February and in the mean time I was gone for most of January to the Cape Winelands in South Africa. Back home in The Netherlands, Europe, I found that most of the free SO2 levels were still at about the same levels as more than 4 weeks ago, so the floating lid - stainless steel tanks from Speidel do their jobs good in keeping oxygen away from the developing wine.

Riesling 2021
At harvest in the Alsace, France, the grapes had a lot of acidity this year (TA more than 10). The pH was low at that time at around 2.9. Whole grape-bunch pressed. Natural fermentation. Towards the end of the primary fermentation, I wanted to leave some residual sugar in the wine to offset the acidity, so I brought the temperature down to 2 degrees C, so basically cold crashed the wine. This stopped the fermentation with about 8 gr residual sugar left. While away in January, I had a nearby winemaker check each week the wine visually (to check for any problems with the glycol coolers or leakage issues). I have just now yesterday measured the pH, free SO2 and acidic acidity: pH went down to 2.61, free SO2 levels about the same and good and acidic acidity within normal range. The wine tastes flipping good. The acidity is there but doesn't taste harsh and is balanced out with the residual sugar. Still, the TA is >10 so I would be tempted to take out some of the acidity like 0.5 or 1, which would also increase the pH to a bit more "normal" figure. Some winemaker friends advise me to do nothing except sterile filtration before bottling. Others suggests to take out a bit of acidity. What would you guys go?

Montepulciano Rosé 2021
These grapes were bought from Italy and came by cooled transport to Belgium where I picked them up. Destemmed them, let that sit for 2 hours before pressing. Then fermented on the gross less (did not rack that off) as an experiment. Now I have this fully tasting rosé wine sitting in the tank which tastes full, but towards the end I taste this "moldy", ground-taste bitter aftertaste a bit. I want to force carbonate this wine to create a sparkling rosé so I need to get rid of this bitter aftertaste. I was thinking of using a bit of PVPP or active coal, then rack it off, filter it at 0.65 and then let it sit a while again to see what the results are. What would you guys do?
 
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sjjan

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if the Riesling tastes fine leave it alone and bottle.
for the rose try a bench trial with gelatin may remove the astringency.
Gelatin? Or PVPP? Seemingly according to this article gelatine is more effective in reducing bitter after taste. Thanks. Had not thought about gelatine yet so far. :)
 
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balatonwine

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Riesling 2021
At harvest in the Alsace, France, the grapes had a lot of acidity this year (TA more than 10).

...snip....

Some winemaker friends advise me to do nothing except sterile filtration before bottling. Others suggests to take out a bit of acidity. What would you guys go?

Riesling is a wine that normally has very high acidity. That is one reason it ages so well. I suggest you leave it alone, bottle it as is and forget it for at least 5 years (or more). If you wanted a more accessible early to bottle and drinkable wine, suggest Pinot Gris (aka in Italy, Pino Grigio).
 

balatonwine

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From another thread, you seemed to have made this wine with a natural fermentation. If you did this for resale and economic reasons, that is a natural fermented wine might get a larger price tag, then consider also avoiding gelatin. Why? Because if you add gelatin you can not call your wine "vegan".... and "vegan" might also may increase its marketing value. Just saying..... :cool:

Of course if you did other non-vegan things.... to late for that.... go for the gelatin if you wish. :)
 

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My only comment regarding a pH of 2.61 is that you have to be careful about the SO2 level, a very low pH means that a greater portion of the SO2 in solution is in the molecular form, usually we think this is good, but the problem is that even at .8ppm molecular you'll only have 6ppm free SO2. That doesn't leave much SO2 to account for oxygen pickup during bottling; 4ppm free SO2 can be lost to 1ppm oxygen pickup. My point here is that typically a little extra SO2 is added for the bottling process, but with a pH of 2.61, the free SO2 range is narrow, too much may be detectable in the nose if early drinking is desired, too little leaves the wine susceptible to oxidation or potential browning.
 

sjjan

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From another thread, you seemed to have made this wine with a natural fermentation. If you did this for resale and economic reasons, that is a natural fermented wine might get a larger price tag, then consider also avoiding gelatin. Why? Because if you add gelatin you can not call your wine "vegan".... and "vegan" might also may increase its marketing value. Just saying..... :cool:

Of course if you did other non-vegan things.... to late for that.... go for the gelatin if you wish. :)
The wine is clean of any foreign stuff or agents. That was my goal initially but in the end the wine needs to be good wine to drink first.
 

sjjan

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My only comment regarding a pH of 2.61 is that you have to be careful about the SO2 level, a very low pH means that a greater portion of the SO2 in solution is in the molecular form, usually we think this is good, but the problem is that even at .8ppm molecular you'll only have 6ppm free SO2. That doesn't leave much SO2 to account for oxygen pickup during bottling; 4ppm free SO2 can be lost to 1ppm oxygen pickup. My point here is that typically a little extra SO2 is added for the bottling process, but with a pH of 2.61, the free SO2 range is narrow, too much may be detectable in the nose if early drinking is desired, too little leaves the wine susceptible to oxidation or potential browning.
Yes, good point. I thought that maybe by just increasing the temperature again from 2 to e.g. 8 degrees some of the tartaric acid would resolve into the liquid again, but seemingly it is all a bit more complex. I thought that by cold crashing some tartaric acid would fall out, but did not consider the idea that the pH would actually drop instead of rise.
 

sjjan

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Gelatin is animal based. It probably works the best, but I am not sure about the US, but here in Europe, it would probably be best to do something like PVPP which is synthetic. It might not work as well, but for sales purposes, it doesn't look good to use animal-based products in wine over here. What are your thoughts about it?
 

stickman

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I don't have direct experience with fining other than bentonite, but given the volumes you typically produce, bench trials would be recommended. The lab handbooks, such as Scott Labs, are a good source for a general guide, based on this it looks like PVPP or potassium casenate might be worth a bench trial, both of these indicate a potential "freshening" of the wine. It seems to me that fining involves a little bit of voodoo, so it's best to test first on a smaller volume.
 
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