Whether or not you should refrigerate a peanut butter and jelly (PB&J) sandwich depends on several factors, including the ingredients used, personal preference, and how long you intend to store the sandwich.
If you are making a PB&J sandwich with shelf-stable ingredients like store-bought peanut butter and jelly (that don't require refrigeration even after opening), then you do not need to refrigerate the sandwich immediately. These products are formulated to be safe at room temperature for a certain period.
However, if you are using natural peanut butter without preservatives or homemade jelly, or if you plan to store the sandwich for an extended period (more than a few hours), then refrigerating it is recommended. Natural peanut butter and homemade jellies may have a higher risk of spoiling at room temperature, and refrigeration can help maintain their freshness and safety for a longer time.
Additionally, if the sandwich contains perishable ingredients like sliced fruits or other toppings that require refrigeration, it's better to store the sandwich in the fridge to prevent any potential foodborne illnesses.
To sum up, if your PB&J sandwich contains only shelf-stable ingredients and you intend to consume it within a few hours, refrigeration is not necessary. However, if the sandwich includes perishable ingredients or if you plan to store it for a longer time, it's best to refrigerate it to ensure food safety and quality.