Why Does Some Peanut Butter Separate While Other Brands Never Do?

A woman in a white bathrobe spreads peanut butter onto a piece of bread at a table. Exploring the food science behind jar consistency helps explain why some peanut butter requires stirring while homogenized options never separate. Pexels.

If you have ever opened a jar of peanut butter and found a layer of oil sitting on top, there is usually a simple reason. Peanuts naturally contain a significant amount of oil, and that oil can separate from the solid peanut particles over time. This is especially common with peanut butter made from a short ingredient list that includes mostly peanuts and salt. When the jar sits undisturbed, the heavier peanut particles settle while some of the natural oil moves upward. The result is the familiar layer of oil that shoppers often have to stir back into the peanut butter.

Some Brands Add Ingredients to Keep It Smooth