Bought some per tube sheep casings. They were given to me in a zip lock bag and some water or brine. How long will these last.
Packed in salt, a long long time.
I know if they are packed in salt they will last. THESE ARE NOT . They gave them to me in a liquid.
Is it a white cloudy liquid? That would be like a salt brine.
I'm assuming since they are in a Ziploc bag they were given to you by a friend, and not purchased. You should be able to drain them, pat them dry with paper towels and repack in salt. Only use kosher, or canning/pickling or purified salt. As Giz stated, if packed in salt they will last indefinitely.
To use after packing in salt; take the amount out that you need, rinse the salt off and soak in lukewarm water, for at least 30 minutes changing the water at least once, and then flush the insides out. The last 15 - 20 minutes of soaking I add vinegar to the water to make the casing more tender and translucent. The soaking rehydrates the casings and removes most of the salt.
I GOT THESE A A BUTCHER SHOP.
Check with the butcher, but usually unless they are packed in salt, they are meant for use within a week or so. See Habs post above for how to pack them.