Oxidation after bottling/recorking

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Mar 3, 2024
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West Midlands, UK
I have recently made pear wine. I bottled after 2 months, and then 2 months after that I have opened a bottle to discover it tastes a little bit sour.
I have some acid reducing crystals which I am told can help, and was hoping I could open my bottles, add the crystals, then recork and see if it improves. However from researching it seems that as soon as I take the cork off, oxygen will come into contact with the wine and it won't last more than a few days.

I find this confusing, as my wine was exposed to oxygen multiple times when re-racking, and also when bottling. Why would opening the wine to add my acid reducing crystals affect the wine, when it has already come into contact with oxygen earlier in the process?

Help would be greatly appreciated as I can't seem to find a clear answer anywhere.
Welcome to WMT!

It’s not that opening the bottles will be detrimental, but that leaving them open without any protection will be detrimental.

The vast majority of winemakers use potassium metabisulfite (aka Kmeta, or sulphite). Sodium metabisulfite was used back in the day before Kmeta became economical and available. Kmeta should be mixed into the wine at a ratio of 1/4 tsp for 5 gallons of wine. It should be used once the wine has fully fermented, and the carbon dioxide that the yeast was generating is no longer protecting the wine.

CO2 can also be used as some bulk age wines in kegs. CO2 can dissolve into the wine thus potentially making it sparkling. Argon would be the gas of choice for reds.
Thanks for your reply!
I have added campden tablets at different points in the process, I believe this is the same thing?

So you're saying it would be okay for me to open the bottles, add the acid reducing crystals and then recork? And are you recommending that I use campden tablets instead of the acid reducing crystals?

If you have a scale that can measure 0.01 grams then you can add your crystals and the campden tablet (ground up of course). Yes campden is the same as Kmeta, just in tablet form.

If you don’t have the ability to measure really small amounts of powders, I would suggest uncorking all the wine, measure out your ingredients and add them to the carboy/jug of wine. At this time I would adjust the taste, let it age another month, re-taste and then decide whether to rebottle or adjust again. Note that each time you open the carboy or jug, you are exposing the wine to oxygen. At some point you should bottle rather than risk continuing to keep exposing the wine to air.

I don’t know what your acid reducing crystals are. Do they have a technical name?
Welcome to WMT!

Most fruit (non-grape) wines benefit from at least a little backsweetening. You might want to try adding a little sugar or simple syrup at serving to see if that fixes the sour taste.

If you do end up backsweetening the whole batch, you will need to add potassium sorbate in addition to the Kmeta, to ensure fermentation won't restart in the bottles.

Kmeta comes in the form of campden tablets as well as powder. The instructions for the campden tablets I have are 1 crushed tablet per US gallon. The powdered Kmeta I have says 1/4 teaspoon for 5 or 6 US gallons.

Kmeta protects against oxygen, and it also kills yeast and other microbes. I use it every time I rack after fermentation is complete, at bottling time, and about every 3 months on bulk aging wines.

It would be used in addition to the acid reducing crystals. If it were me, my procedure would be to measure out some samples of the wine, bench test with added acid reducing crystals OR backsweetening. If either of these seems to fix it, I would unbottle the wine back into a sanitized bucket, and stir in about half of the acid reducing crystals OR sugar calculated for the full batch based on my bench testing. Sample again to see if more is needed (you can always add more but you can't take the acid reducing crystals or sugar back out).

If you decide backsweetening is the way to go, add potassium sorbate in addition to the Kmeta to ensure any remaining yeastie beasties don't start eating the newly added sugar!

As Bob says, I would leave it in an airlocked carboy for a month or so and sample again to see how the taste is, and adjust again if necessary. You would not need to add any more sorbate, however - that needs to be added only one time, before backsweetening.
Yes campden is the same as Kmeta, just in tablet form.
I would just caution that the name 'Campden tablet' is used for both sodium and potassium metabisulphite, depnding on the vendor... or even in different packages fom the same vendor!


To the original question - I agree with others who have said that opening and recorking won't substantially damage the wine unless it's left open for a long time. Regarding deacidification, I'm guessing it's calcium or potassium carbonate? I don't have personal experience using these, but I do know it's more subtle than just adding to the wine. Typically the wine is racked after precipitation; from what I read, the potassium salt needs to be cold stabilized in order to precipitate whereas calcium does not, but calcium is more likely to affect flavor. The reaction also evolves CO2, so you wouldn't want to recork immediately for fear of pushing those corks back out...

If it were me, I'd do a trial deacidification on one bottle, decant off and compare (sensory) with the unadulterated wine. If you like the result, it's a pain to do but I'd uncork all the bottles, pour them into a suitable vessel (carboy, tank etc) and deacidify in bulk, then rack back to bottle.

ETA: Rereading @Jovimaple 's comment, who makes a good point about sweetening. Adding even a small dose of sugar can dramatically impact the perceived sourness. I'd be inclined to try this first.
I have some acid reducing crystals which I am told can help, and was hoping I could open my bottles, add the crystals, then recork and see if it improves.
How do you know that the problem is too much acid? How much acid did you add in your recipe? To really find out, you need to measure the pH or TA .

Most fruit fines taste sour without a little backsweetening. As @Jovimaple suggested, try adding a little sugar to a sample and see if that improves the flavor. Generally, you need a balance between acid, tannin/bitterness, and sweetness to have a good wine.
@lucagianni welcome to WMT.

* I have done opening and recorking. Yes it adds some oxygen to the head space. On a relative risk a natural cork is rated to add about 5mg oxygen in the first year. Other than with tools like nitrogen flushing combined with aluminum caps one cannot get away from some oxygen.
* If I needed to add a small quantity of meta per bottle I would mix a 1:10 solution and add it with a syringe (I can get a syringe at the pharmacy). There is a liquid “wine conditioner “ available in the states which has a sugar solution and sorbate, again syringe it.
* It is said that wine gets sweeter as it ages and a wine for storage should have extra acid added. In wines I have looked at over time this seems to be in the 0.1% decrease in titratable acidity per year.
* Grocery products are more stable with acid. Factories go to length to make sugared foods shelf stable, ,,, because folks on the average like sugary tastes. ,,,, If you deacidify or sweeten is personal preference BUT a pH below 3.5 is suggested for shelf stability.

* I would doctor the wine as I need it, ,, not a whole case. Sugar will balance the flavor of excess acidity and doesn’t have any reaction chemistry.
Oxidation chemistry to get to where one tastes it is measured in weeks or even months.
Some acid reducers can release CO2 what chemical were you going to use? A bicarbonate will react in minutes.