Replacing Potassium Metabisulfite

[Huba Huba]

I don't have a way to measure free sulfite but try to remember to replace my K Meta every 6 months. I recently bought a new LD Carlson 2 oz package, Looking on the internet the consensus seems to be that K Meta should be good for 12-18 months from manufacture. There is no date, "manufacture" or "best by" or even a lot number on the package, or on any of the old packages I still have. I always thought that it was good for up to 6-12 months after opened. As far as I know any package I buy could have been sitting on a shelf for 18 months.
How do you know if it is good?

 

[winemaker81]

I make enough wine that I typically buy an 8 oz bag every 12-18 months, depending on usage. However, I've used K-meta that was 2 years old.

Make up a K-meta sanitizing solution, with 2 to 3 Tbsp K-meta in 1 US gallon / 4 liters water with optionally 1 Tbsp acid. Sniff it VERY gently. If it burns your sinuses, it's plenty good.

I'm paranoid about sorbate, as when sorbate ages out, the risk is a batch of mini-Mount Vesuvius, e.g., refermentation in the bottle. If the K-meta reeks, it's still at least somewhat effective so I'm a lot less concerned.

 

[BarrelMonkey]

I make enough wine that I typically buy an 8 oz bag every 12-18 months, depending on usage. However, I've used K-meta that was 2 years old.

Make up a K-meta sanitizing solution, with 2 to 3 Tbsp K-meta in 1 US gallon / 4 liters water with optionally 1 Tbsp acid. Sniff it VERY gently. If it burns your sinuses, it's plenty good.

Sniff test is good. I would also add that if it's stuck together in big clumps it's also time for a new batch - you want it to be dry and powdery so that it can be accurately measured and dissolves fully before adding to your wine.

 

[Rice_Guy]

As a chem lab person, if the potassium metabisulphite is dry it will have years of shelf life. On chemicals I am concerned about I store them in glass. Meta reacts with metal so a plastic lid or at least a Saran liner should be used.
I make a sanitizer with meta. My test for effectiveness is carefully waft some headspace at my noise. It should burn if free SO2 present. On wines if I don’t test, I assume country wines are zero ppm and reds are about 10ppm.

 

[Huba Huba]

OK, sounds like replacing my K Meta every 6 months should keep me out of trouble. I did not know that I needed to do the same with K sorbate, I will start replacing that every 6 months also.
Do you worry about chems included in kits? I have bought a couple of RJS Dessert wine kits recently on sale/closeout and will not make them for a couple of months. Removed/refrigerated the yeast, should I just discard the Meta/KSorb that came with the kits and use my "fresher" ones.

 

[winemaker81]

OK, sounds like replacing my K Meta every 6 months should keep me out of trouble. I did not know that I needed to do the same with K sorbate, I will start replacing that every 6 months also.
Do you worry about chems included in kits? I have bought a couple of RJS Dessert wine kits recently on sale/closeout and will not make them for a couple of months. Removed/refrigerated the yeast, should I just discard the Meta/KSorb that came with the kits and use my "fresher" ones.

IME you don't need to replace K-meta or sorbate every 6 months.

Vendor docs indicate sorbate, in correct storage conditions, is good for 2+ years. Since mine is in a drawer in a clear plastic bag, I keep mine 12-15 months, which allows for time in the warehouse and on the LHBS' shelf. I have never had a problem doing this.

My habit is to date EVERYTHING when I buy it.

 

[Rice_Guy]

OK, sounds like replacing my K Meta every 6 months should keep me out of trouble. I did not know that I needed to do the same with K sorbate, I will start replacing that every 6 months also.
Do you worry about chems included in kits? I have bought a couple of RJS Dessert wine kits recently on sale/closeout and will not make them for a couple of months. Removed/refrigerated the yeast, should I just discard the Meta/KSorb that came with the kits and use my "fresher" ones.

This is excessive, , unless these chemicals get wet. They are shelf stable with dry normal warehouse storage.
K metabisulphite has years of life in the original plastic bag. On a percentage free SO2 calculation the pH of your juice / wine will be more important than the years in a plastic bag. The percentage error on how much we fill onto the plastic bag is more than the loss over five years. Sorbate is more reactive to humidity but again has years of life when in normal US storage. If I was in the Amazon with rain every day I could chart the water vapor transmission rate of the plastic bag and then have some concern. IF humidity was a serious issue for the manufacturer we would package those chemicals in aluminized film like seasoning packets in ramen noodles and flavored rice mixes. These films are rated to have vapor transmission rates like glass bottles and as Barrel said if the chemical has formed a lump it has degraded.
Yeast packets are designed for over kill, they out compete any wild yeast you might have in your equipment. On a practical basis if I have one live yeast cell out of the millions in a yeast packet it will ferment, but with a slow start up.

Some of the company’s best by code dates were chosen because the packaging starts to fade under the fluorescent lights in a store. The feeling was that it would be hard to sell.

 

[winemaker81]

@Rice_Guy, do you believe my "toss sorbate after 12-15 months" is too paranoid? I won't be offended if you do, as I respect your opinions regarding the chemical side of winemaking.

I'm a touch, see, and feel guy. With K-meta I can dissolve a small amount in water and gently sniff it. If it makes me cough my lungs out, I know it's good.

With sorbate, the only way I'll know that it's degraded too much is by having cases of wine blowing their corks. I had that happen once (caught it early, so only pushed corks partially out), and had to rebottle 2 cases of wine. From my POV it's cheaper and easier to buy small packages of sorbate (when I need it), and bin the small amount that remains after 12 to 15 months, than it is to unbottle 2+ cases of wine and later rebottle them.

As mentioned above, I looked at vendor docs, consider that the package spent an unknown amount of time in the warehouse and on the LHBS' shelf, and consider my less than stellar storage conditions.

You mentioned yeast -- that's a good reason to make a starter. My package of Avante will be used in the 5th ferment next fall. I'll make starters, and will know within 10-30 minutes if my yeast is viable. [Touch, see, & feel!]

All that said, my practice is to buy additives in quantities that will be used up in a year or so, then buy more at the time it's needed. This eliminates the question, "is it too old?". [Any powders that clump are immediately binned.]