Starsan expiry date
- Thread starter bleachin
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MyQul
Chairman of the Bored
Pretty sure It's just a legal requirement. I've had my bottle of star san for a few years now and it's probably gone past it's exp. date. It still perfectly fine
According to its Safety Data Sheet Starsan appears to be made of an aqueous solution of two chemicals, phosphoric acid and dodecylbenzenesulfonic acid (!). Phos acid is stable and I can only guess that it's the phos acid that is the active sanitising agent by creating an acidic environment that kills bugs, so even after a long time in store that part should be OK. The other stuff is a surfactant but apparently under aerobic conditions it will slowly degrade. In anaerobic conditions it won't. So my take would be it's OK to keep Starsan in your store for a few years provided you don't keep shaking the bottle and/or exposing it to lots of air, which you won't, but it will lose some of its wetting capability over the years, so it probably needs chucking out after say 5 or 6 years assuming you have some left in your bottle.
According to this: https://lifefermented.wordpress.com/2013/06/18/brew-tips-cloudy-starsan/ it's actually the DBSA that is the active ingredient (I don't know much about this but possibly acts like an oxy-bleach only not with chlorine??) and the Phosphoric Acid is there to keep the pH low enough for the DBSA to do it's job. So if the DBSA has degraded then potentially the Starsan is not doing its job. I would like to think that this isn't the volatile ingredient though - that would suggest that it was susceptible to oxidation or degredation but we know we can keep starsan in diluted form without any special storage precautions, so that wouldn't otherwise make sense. I suspect it is something to do with the sufactant, like you say.
