17. Mustard
Like ketchup, there are acids in mustard that act as natural preservatives. Mustard will stay good for about a month in the cupboard. Whether to refrigerate a bottle of mustard comes down to a matter of taste. Do you like cold or room temperature mustard on your sandwiches?
16. Aged Cheese
The difference between aged cheese and other types is that it is cured. This process usually takes about 6 months. If these cheeses are put in the refrigerator they tend to get very hard.