# Sodium metabisulphite



## wineview (Feb 26, 2019)

how long can I keep this in a bucket before it becomes ineffective. I know that as soon as Star San gets cloudy it’s properties are lessened. Does sodium metabisulphite have a shelf life as well. 

Thanks


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## Scooter68 (Feb 26, 2019)

Cloudy Star San does not mean it's ineffective. The pH reading of the solution is the best indicator. 
I can make fresh starsan with our tapwater and it's cloudy immediately. 

Cloudiness is not desirable but it's not a foolproof indicator either.


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## wineview (Feb 26, 2019)

Scooter68 said:


> Cloudy Star San does not mean it's ineffective. The pH reading of the solution is the best indicator.
> I can make fresh starsan with our tapwater and it's cloudy immediately.
> 
> Cloudiness is not desirable but it's not a foolproof indicator either.




Understood but I think you may be in the monority. Having said that how long does sodium metabisulphite last in storage.


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## Ct Winemaker (Feb 26, 2019)

If your asking about potassium metabisulphite, we were tought that once mixed, as long as it still has it’s potent smell, it’s good for cleaning. In regards to the powder for use directly in the wine, about 1 year once the package is open. If you meant sodium meta, sorry for the providing the above info.


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## wineview (Feb 26, 2019)

Ct Winemaker said:


> If your asking about potassium metabisulphite, we were tought that once mixed, as long as it still has it’s potent smell, it’s good for cleaning. In regards to the powder for use directly in the wine, about 1 year once the package is open. If you meant sodium meta, sorry for the providing the above info.



I meant once mixed with water how long does it remain effective for sanitizing.


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## Ct Winemaker (Feb 26, 2019)

As long as it still has the potent smell. (Again assuming your asking about potassium meta, not sodium Meta). That’s according to what we learned at Musto’s wine making boot camp.


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## wineview (Feb 26, 2019)

Ct Winemaker said:


> As long as it still has the potent smell. (Again assuming your asking about potassium meta, not sodium Meta). That’s according to what we learned at Musto’s wine making boot camp.



Sodium Metabisulphite


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## NorCal (Feb 26, 2019)

I would think it would depend on how it’s stored. I’d bet a 50ppm solution, an inch thick in a 5 gallon bucket would be under 10 within a week or two. A 50ppm in a full spray bottle would probably be 45 ppm after 3 months. 

The SO2 is a anti-microbial and an anti-oxidant. Open to the air, the free SO2 will combine with the O2 and reduce in short order.


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## wineview (Feb 27, 2019)

NorCal said:


> I would think it would depend on how it’s stored. I’d bet a 50ppm solution, an inch thick in a 5 gallon bucket would be under 10 within a week or two. A 50ppm in a full spray bottle would probably be 45 ppm after 3 months.
> 
> The SO2 is a anti-microbial and an anti-oxidant. Open to the air, the free SO2 will combine with the O2 and reduce in short order.



How do you measure ppm?


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## jgmillr1 (Feb 27, 2019)

wineview said:


> how long can I keep this in a bucket before it becomes ineffective. I know that as soon as Star San gets cloudy it’s properties are lessened. Does sodium metabisulphite have a shelf life as well.
> 
> Thanks



For sanitation, sodium metabisulfite works fine. The potassium variation is the one that must be used in your wine.

The metabisulfite solution must be acidified to be effective. I use one tbsp of citric acid and one tsp of metabisulfite per gallon of water. This gives a whopping 700+ppm of sulfites that are nearly 100% active because of the low pH.

As far as how long it lasts, that depends on it you return "dirty" solution back your bucket and whether it is open to the air. The sulfites will outgas (why you smell it) and lower the concentration in your container. A spray bottle should be good for over a month. An open bucket probably is only good for the day you are using it.


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## jgmillr1 (Feb 27, 2019)

wineview said:


> How do you measure ppm?



Ppm = mg / liter
Potassium metabisulfite is 57.6% sulfites.

So 1g of potassium metabisulfite mixed into 5 gallons yields:
0.576 * 1000mg / (5 gal * 3.785 L/gal) = 30.4 ppm sulfites

Note that some of the sulfites become bound to aldehydes, sugar and other compounds.

Also the portion of the sulfites which are active (H2SO3) are a strong function of pH. Much less effective at higher pH.


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## cmason1957 (Feb 27, 2019)

jgmillr1 said:


> For sanitation, sodium metabisulfite works fine. The potassium variation is the one that must be used in your wine.



I have to take some very small exception to that statement. Sodium metabisulfite can be used in your wine, it will increase the overall sodium in the final product and may lead to a salty taste in the wine, but in a pinch and one time, if you have no potassium and do have sodium. It isn't an absolute must use, but good idea and best practice.


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## wineview (Feb 27, 2019)

jgmillr1 said:


> For sanitation, sodium metabisulfite works fine. The potassium variation is the one that must be used in your wine.
> 
> The metabisulfite solution must be acidified to be effective. I use one tbsp of citric acid and one tsp of metabisulfite per gallon of water. This gives a whopping 700+ppm of sulfites that are nearly 100% active because of the low pH.
> 
> As far as how long it lasts, that depends on it you return "dirty" solution back your bucket and whether it is open to the air. The sulfites will outgas (why you smell it) and lower the concentration in your container. A spray bottle should be good for over a month. An open bucket probably is only good for the day you are using it.



Citric acid added to Sodium Metabisulfite for sanitation purposes correct?


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## NorCal (Feb 27, 2019)

wineview said:


> How do you measure ppm?


It was an investment that was a bit hard on the wallet, a Vinmetrica 300. It is for the reason of not knowing what the efficacy of the cleaning solution after storage that I use StarSan. If I had aciduated water and fresh SO2 and you used it right away, then all should be fine. I would trust my mixture of StarSan weeks later, but wouldn’t have the same confidence with an SO2 solution.


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## jgmillr1 (Feb 27, 2019)

cmason1957 said:


> Sodium metabisulfite can be used in your wine



Not legally though. See the approved list here. {Updated link}



wineview said:


> Citric acid added to Sodium Metabisulfite for sanitation purposes correct?



Yes, citric should be added regardless if you use potassium or sodium metabisulfite.


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## Scooter68 (Feb 27, 2019)

During a previous round of these "How long does it last?" Back & Forth discussions I tested 4-5 week old batch of Star San. The pH came in at about 2.7 well within the useful range. One more reason I use it.


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## sour_grapes (Feb 27, 2019)

jgmillr1 said:


> Not legally though. See the approved list here.



I am confused. I don't see _any_ sulfites on that list.


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## cmason1957 (Feb 27, 2019)

sour_grapes said:


> I am confused. I don't see _any_ sulfites on that list.



I agree, no sulfites are listed at all.


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## jgmillr1 (Feb 27, 2019)

sour_grapes said:


> I am confused. I don't see _any_ sulfites on that list.



Sorry that was an incomplete list. The entire section of the code is here. Look at the table in section 24.246 and you'll find potassium metabisulfite


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## cmason1957 (Feb 27, 2019)

jgmillr1 said:


> Sorry that was an incomplete list. The entire section of the code is here. Look at the table in section 24.246 and you'll find potassium metabisulfite


That link didn't go to a specific thing, just the search site. I'll believe you that Sodium metabisulphite isn't allowed in commercial wines. I don't own any, but those laws and list of allowed items don't apply to home winemakers.

Actually from a real computer, not a tablet/phone, the link worked great and there is no mention of Sodium Meta-Bisulphite as reported.


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## wineview (Feb 28, 2019)

Scooter68 said:


> During a previous round of these "How long does it last?" Back & Forth discussions I tested 4-5 week old batch of Star San. The pH came in at about 2.7 well within the useful range. One more reason I use it.



Do you use PH strips or something more sophisticated?


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## Scooter68 (Feb 28, 2019)

I use a pH meter. Litmus paper (Paper strips) are of no use to me since most of my wines are dark wines. And I wouldn't buy special Litmus paper to be able to read a pH that low for a one time test of my StarSan solution.


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## wineview (Mar 1, 2019)

Scooter68 said:


> I use a pH meter. Litmus paper (Paper strips) are of no use to me since most of my wines are dark wines. And I wouldn't buy special Litmus paper to be able to read a pH that low for a one time test of my StarSan solution.



Below 3 for Star San correct?


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## Scooter68 (Mar 1, 2019)

wineview said:


> Below 3 for Star San correct?


Yes.


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