Traditionally butter was produced by churning fermented sour cream using a discontinuous process, which also resulted in large volumes of acid buttermilk as a by-product. Nowadays, butter is usually made according to the NIZO butter process, which was developed at NIZO in the 1960’s. In this process, sweet cream, rather than fermented sour cream is churned and acidification and aroma formation in the butter occurs only after the sweet cream has been churned. Aroma can be formed by using lactic acid, distilled butter aromas and the inclusion of aromatic starter cultures, which can be worked into the butter. A major advantage of the NIZO butter process is that the sweet buttermilk that is created during this production process is a co-product and not a by-product. The sweet buttermilk is easy to use as an ingredient in a wide variety of dairy industry applications or as a starting material for the isolation of functional ingredients, such as milk fat globule membrane material.