Mustard
Another spice that is often tossed into the refrigerator without much thinking is mustard. However, there is no need to do so. Like ketchup, mustard has a high acidity concentration, which makes it a self-preserving condiment. When was the last time you saw a restaurant refrigerate its mustard? Nope. As a result, neither do you.
It all comes down to individual preference. It depends on the individual whether they prefer their mustard warm or cold. Make a well-informed decision. Or may stay on the safe side and dont use the refrigerator for it, the food may not taste good with cold mustard on it, eww.