Nutrients out of date?

How do you know if you nutrients are out of date?
Bought mine 1 year ago and did 1 grow with it.
Now 1 year later the bottles are dented sucking themselfs vacuum

Sounds like organic products(?) If so...they should still be good after only a year. A lot of stuff has been on the shelf that long and you can see bottles at the hydro stores/nurseries doing the same thing. I'd shake the heck out of it and maybe even transfer it to another bottle to ensure there's no gunk stuck at the bottom/nothing is getting left behind.

If in doubt bin it. no point in starting a grow with doubt. Happy growing.

Thanks for the reply guys. Yeah its organic
Bac organics is the name

Really wanted to try ghe flora or flora nova anyhow so maybe ill just do that now