I've been splitting yeasts and storing them in the fridge in 500ml plastic bottles with 200ml sterile water; I have about 12 and have just noticed that 3 have a white film on the surface of the water and smell a bit sour. I'm going to chuck them rather than trying to salvage them. Last week I unsrewed the tops of a few to check if pressure was building up, but other than this I can't think of any reason why this has happened.
Has anyone had similar problems?
Has anyone had similar problems?