❄️ Cooling

Cooling is the main way to keep raw milk fresh. Milk leaves the udder warm, at about 37 °C, and for bacteria this is almost ideal. For the first 3–4 hours, they are held back by milk's natural protective substances, lactoferrin and lactoperoxidase. Within this time, the milk must be cooled to +4 °C.

On the farm, milk is cooled in a cooling tank, often after first passing through a plate cooler with cold water. On small farms, churns are placed in cold water, or immersion coolers are used. Where there are no fridges, the FAO advises boiling milk right after milking or keeping the churns in cool water, for example in a stream. The Codex Alimentarius (an international collection of food standards) approves one more method, the lactoperoxidase system. It extends the life of raw milk by 7–8 hours at 30 °C, but only trained people at collection points should use it.

In the EU, milk on the farm must be cooled to no more than 8 °C if it is collected every day, and no more than 6 °C if it is collected less often. According to the FAO, cooling has the biggest effect on the quality of raw milk.