How old is too old?

I am sure this has been covered, but I just cannot find it anywhere....

I have a packet of Wyyeast Sweet Mead strain. It was Mfg in 2010 according to the packet....it is been in the refrigerator the entire time.

I bought it to make 2.5 gallons of simple cider....so is it too old?

No it's not too old. Just make a starter with a pint or so of apple juice and I'll bet it takes right off. I've started yeast that old, it usually just takes a couple days to wake up and you definitely want to make a starter to propagate/check for viability.

OK, great! Will definitely use a starter!

Go ahead and smack it too, but don't be discouraged if it doesn't puff up. There's living yeast in there for sure.

Check the starter after it has fermented. I have tried to revive yeast that old and wildyeast took hold and made clovey bandaid beer. If the starter tastes and smells normal then you should be OK but there is some degree of contamination even in sealed liquid yeast and after so much time it can take hold. The starter smelled very clove I should have known better but I went ahead and pitched it into a batch. Suffice to say it was a dumper.