Storage is THE key. Caviar in vacuum-sealed jars (that haven’t been opened) will maintain its freshness for five to six weeks (a few weeks longer if stored on ice in the refrigerator). Unopened tins will be fresh for about 2 weeks or perhaps sometimes more. Once a jar or tin is opened, the caviar should be consumed within 2-3 days for getting the maximum flavor out of it. It can be eaten beyond then, but it begins to deteriorate.