I have a box of raisins in my cabinet that have been there for many years. Should I discard them or can they still be salvaged for use in baking or cooking?
According to this Sun Maid specification sheet, the shelf life is up to one year, and they contain about 15% water.
This is probably not sufficiently dehydrated for truly long term storage, and mold would be a risk. Also, if they did dry further in storage they would be rock hard, and probably quite nasty.
They usually spray the raisins with Sulphites to preserve them. The ones with sulphites look a little shiny whereas the ones without look a little chalky (but taste better to me).
If your cabinet is not very humid, chances are they have not gone bad. Otherwise you might see 'signs of life'.
However, the good shelf life of raisins is about a year. They are likely to carry an off taste and mess with your cooking/baking flavours.