Recently I was making a venison and pork dried cured sausage and decided to ferment it with the expired culture. I added about .75g/kg, about 50% more than the suggested amount and had excellent results. After 42 hours at 21C, the pH dropped to 4.9 from 5.8. So the lesson here is that starter cultures don't just die on the expiry date and we should not be too eager to pitch them. Some time ago Igor Duńczyk wrote on our forum that with time, the cell count or the number of live cells does go down, but they all don't give up the ghost simultaneously. So if using older cultures, add a bit more and you should still have good fermentation. Just make sure you store them tightly sealed and frozen at -20C (-4F).
