Q. I bought a large amount of prepared mustard and now am left with too much to store on shelf. Can mustard be kept in the freezer?
How much mustard did you buy? Stored in the refrigerator, prepared mustards have a relatively long shelf life anywhere from 6 months to 2 years, depending on the fuss-level of your taste buds. The presence of light, oxygen, and heat reduces the pungency or strength of mustard. So storing your excess, or wealth, of mustard in a container that is just the right size in the refrigerator should keep your mustard at or near full strength for many months. From the perspective of food safety, mustard stored in a refrigerator is safe indefinitely.
We haven't found anyone or any source that approves of or suggests freezing mustard for long-term storage. A couple of manufacturers we contacted tell you not to do so.