Sometimes, a search engine term shows up in my stats that I feel I should address. Today, it’s this:
ypd media does it ever go bad
No. Well, it does get contaminated (if it’s cloudy, it looks contaminated). Then, you need to get rid of it. But, in general, I have used media that is a few years old and the cells grew fine (I was desperate and I found some that belonged to some former student). Beyond that, I suppose I couldn’t say, but usually people use their media within a year or so of making it. If you don’t, then you are likely making too much at once which I wouldn’t recommend because of the risk of it becoming contaminated before you get around to using it.
At least, that’s what I assume you mean when you ask if it goes bad. If you are talking about how it gets darker after autoclaving, then I would say that is normal–it’s just the sugar carmelizing. If you leave it in the autoclave longer than a typical 20 minute cycle, it can get quite dark–almost black. It’s still okay to use, though.
There, that’s my public service for today.