I opened a can of sliced black olives for my pizza and only used half. I put the leftovers into a sealed container with the liquid and put it in the fridge. Under those conditions how long will the olives last? Is there a better way to store leftover olives?
Olives are basically cured in salt, so they will last a very long time. They will last even longer if kept in an air-sealed container in a refrigerator. They will last even longer than that if kept in a salty brine which covers them with liquid and minimizes exposure to air.
I would drain them, put them in a glass jar and cover completely with olive oil. Maybe add some flavourings such as dried chilli or orange zest. Covered with oil in the fridge they should keep indefinitely.
According to "Keeping Food Fresh" by Janet Bailey,
Unopened cans of olives keep up to one year on a cool, dry shelf. Once you have opened a can, store the olives completely submerged in their own liquid in a covered container in the refrigerator for one to two weeks. Olives bought in bulk and stored steeped in oil keep several months in the refrigerator. Discard olives that have turned soft.
They should definitely be fine for at least a week when stored in the brine.
They'll last a good few weeks from my experience. There's no real rule though to predict how long they'll keep.
If they are for cooking purposes, just drain, and freeze in portion sized bags.
http://calolive.org/our-story/faqs/ California ripe olives says 10 days after they are opened and put in a airtight container.
I have been eating the same container of black olives for about 3 months. They keep for a LONG time, in fact I've never had any go bad. I keep them in an air dealer container in the fridge. I eat a few here and there and use for cooking. My 15 month old LOVES to eat them like grapes as well. They will keep for months, just smell them before ingesting, you'll definitely know when they are turning!