❄️ Cooling

Cooling is the quick drop in temperature of fresh milk that stops bacteria multiplying. According to FAO, milk’s natural protective substances hold them back only for 3–4 hours, so milk is cooled to 4 °C within that time. On the farm, EU rules allow no more than 8 °C with daily collection and 6 °C with less frequent collection.

There are several methods. The most common is a cooling tank with an agitator, preceded on large farms by a plate cooler with cold water. On small farms the churns are lowered into cold water or a stream: water up to 10 °C works best. Ice should not be put into warm milk, FAO advises.

Tanks are designed to cool milk to 10 °C within two hours and to 4 °C within four (ISO 5708, EN 13732). For milk for raw dairy products, the Codex Alimentarius requires no more than 6 °C with daily collection and no more than 4 °C with less frequent collection, while EU law is milder, so these standards should not be confused. On arrival at the plant, milk has to be no warmer than 10 °C.

Where there are no refrigerators, FAO mentions boiling the milk right after milking and the lactoperoxidase system. The Codex approves it: it extends the life of raw milk by 7–8 hours at 30 °C, but only trained staff at collection points use it.

Why it matters to you. The freshness of the milk in your carton begins in the first hours on the farm: if it was not cooled in time, bacteria have time to multiply. Cooling does not replace pasteurisation but preserves quality until processing. When you buy milk, keep up the cold chain and put it in the refrigerator.