Buttermilk, the main ingredient in ranch dressing, can be stored in the freezer. Ranch dressing is best refrigerated. The dressing stays fresh for one to two months in the refrigerator, whether the dressing bottle has been opened or not.
Buttermilk can be frozen in ice trays. A small amount of buttermilk should be poured into each tray section. Once the cubes are frozen solid, they can be transferred into an airtight freezer bag. When cooks are ready to use the buttermilk, one cube at a time can be thawed to create foods like ranch dressing. If ranch dressing begins to change color, this is a sign that it is spoiled and should be discarded.