There is no Requirement to Refrigerate Tomato Sauce Once It has been Opened.
It is common knowledge that tomato sauce can be kept in the pantry; however, according to a professor of food microbiology, there is no need to refrigerate tomato sauce once it has been opened.
Bremer claims that tomato sauce is highly acidic. This acid prevents bacteria from infecting the sauce. If you keep tomato sauce in the fridge after it has been opened, you can increase its shelf life. For up to 18 months, an unopened jar can be stored in the pantry.