This is a picture of how I save our buttermilk and keep it from spoiling before we can use it up. We frequently use buttermilk to make homemade ranch dressing and sometimes buscuits and pancakes. But we don't always use it up fast enough.
I think I found this tip on Pinterest and have used it successfully for awhile now. I freeze the buttermilk in ice cube trays and once frozen transfer the cubes to a ziplock bag, which I store in the freezer. When I need buttermilk I take out the number of cubes I will use and let them defrost in a bowl. Each cube is 2 tablespoons of buttermilk.