Sodium metabisulfite

Winemaking Talk - Winemaking Forum

Help Support Winemaking Talk - Winemaking Forum:

ChuckD

Supporting Members
Joined
Nov 30, 2021
Messages
734
Reaction score
1,329
Location
NE Wisconsin
I was going through some wine making equipment I purchased and found a five lb bag of sodium metabisulfite. It’s probably five years old and was opened. Can this used for sanitizing? Is it used in place of k-meta for oxidation protection?
 

JohnT

Moderator
Staff member
Super Moderator
Joined
Feb 9, 2010
Messages
10,056
Reaction score
5,908
I would toss it if it is 5 years old.

Update: Although perfectly fine to use, I find that when it gets that old, it tends to get clumpy and hard to measure. For this reason, I normally toss it when it gets that old.
 
Last edited:

Rice_Guy

Supporting Members
Joined
Jan 29, 2014
Messages
2,743
Reaction score
3,513
Location
Food Industry - - Retired
A variety of opinions on your thread, look for consensus;
* sodium is the ion used for creating salty flavors in foods. Sodium was the only version of meta that was available in my Mom’s generation and at that time would have been used in formulating all wines. Today it is preferred that potassium meta is used. Potassium has some salty flavor combined with bitter so it also isn’t the ideal. However, With high acid northern grapes which are high in tartrates there is an advantage to adding potassium metabisulphite and encouraging the bitartrate crystals.
At the level used, 200ppm maximum, over the life of a wine sodium versus potassium doesn’t make much difference.
* Can it be used? First test, Is it dry? Then Yes. The metabisulphite is a stable molecule unless put in water. When in water, especially acidified water it will ionize and produce free SO2. The effective portion of the molecule is SO2 gas which can do functions as remove the natural red color of door county marischino cherries, or for us kill bacteria.
pKa is the pH where fifty percent of the ion converts into the next ion. For meta this is at pH 2.7. is It likely that this meta has been stored at a low pH as 2.7 or for that point even pH 6.7. ,, Well if it is dry extremely unlikely so on that test it is OK.
* Is it effective? Second test. Has the metabisulphite been heated as in an oven or hot car in the Texas sun at 200 F all summer? Meta will decompose under high heat, the longer treated the more toxic SO2 will have been released. The term for your home is frozen tundra so again it should be OK. ,,,, Lab Test; If it has decomposed it won’t burn your lungs.

Risk? With dry metabisulphite held at room temperature the risk at twenty years is similar to making a wine which is pH 3.6 instead of pH 3.5. (remember the molecule is more effective at acidic pH). IF you consider a wine which is 0.1 unit high in pH worthy of being tossed then consider tossing this chemical. ,, Note though that by pulling the pH of your must down 0.1 unit the effective free SO2 with twenty year old meta is back where desired.
Conclusion: for an acidified sanitizer age at room temp doesn’t matter, and since I control the must to be below pH 3.8 I wouldn’t have any problem using it in a wine. While on this I wouldn’t use fresh metabisulphite if the must is above pH 3.8.
Suggestion; hand it out in half pound zip lock bags to folks at the next vinters club meeting. , , , , Everyone makes acidified sanitizer.
 
Last edited:

gsorrells

Junior
Joined
Sep 16, 2021
Messages
6
Reaction score
6
I was going through some wine making equipment I purchased and found a five lb bag of sodium metabisulfite. It’s probably five years old and was opened. Can this used for sanitizing? Is it used in place of k-meta for oxidation protection?
Absolutely you can use it for sanitizing. Assuming moisture has not entered, it’s still good. Generally potassium is preferred over sodium metabisulfite to stabilize wines. We bottle our wines at 30-40ppm sulfite, fyi.
 

Latest posts

Top