🔄 Churning

Churning is how butter is made from cream: it is stirred vigorously, the fat globules stick together into butter grains, and the liquid part, buttermilk, drains off. Under EU law, butter contains at least 80 % and under 90 % milk fat, up to 16 % water and up to 2 % non-fat solids.

Here is what happens inside. During churning a foam of large protein bubbles forms, the membranes of the fat globules partly break down, and the fat comes out. The foam collapses, and the grains, at first invisible, then get bigger. After the buttermilk is drained, the grains are worked to break the water into tiny droplets and pressed so that no droplets can be seen with the naked eye; vacuum treatment lowers the air content to about 1 % versus 5–7 % in ordinary butter.

The cream is pasteurised beforehand, usually at 85 °C for 15 seconds or higher, and then held for 12–15 hours. Batch churns are filled to 40–50 %, and large ones hold 8,000–14,000 L. They are quickly being replaced by continuous machines with a capacity of 200–5,000 kg/h (cultured-cream butter) and 200–10,000 kg/h (sweet-cream butter). Losses are considered acceptable if less than 0.70 % of the cream's fat stays in the buttermilk.

Until the 19th century butter was made from soured cream. Cooling and the separator (1878) made it possible to skim cream before it soured. Cultured-cream butter has a richer aroma and a higher yield, but is more sensitive to oxidation. Finished butter is stored at +5 °C.

Churning or whipping cream? Both start with cream and a vigorous stir, but they end differently. Whipping keeps the fat and air together in a foam. In churning the foam collapses, the fat globules’ membranes partly break down, the fat sticks into grains and the buttermilk drains off; the grains are then worked until no water droplets show to the naked eye. What comes out must hold at least 80 % and under 90 % milk fat to be sold as butter under EU law.

On a pack look for the word “butter”, which EU law allows only for a product with at least 80 % fat; “cultured”, “sour-cream” or “sweet-cream” butter says which cream was churned. Spreads with less fat cannot be called butter. It is sold in the chilled cabinet of supermarkets, dairies and grocers, and the finished butter is stored at +5 °C, so keep it in the fridge.

Why it matters to you. EU law allows the name “butter” only for a product with at least 80 % fat, so check the label.