🔄 Filtration

Filtering milk means removing bits of dirt from it: hairs, specks and pieces of bedding. On the farm, milk is strained right after milking, before it goes into the tank. With hand milking, it is poured from the pail into a churn through a sieve or filter. In a milking system, the filter sits right in the milk pipeline, before the cooler.

At the plant, the milk goes through a mesh filter again when it arrives. Then a centrifugal cleaner (clarifier) removes smaller particles. There is also fine filtering through membranes. Microfiltration through ceramic filters holds back up to 99.9% of germs in skimmed milk and helps extend shelf life. Ultrafiltration lets water and lactose through but holds back protein and fat.

Filtering also means straining soured milk or curd through cloth. This separates out the whey and gives thick products: labneh (strained yogurt), chhena and shrikhand. This is a different process, but the idea is similar: separating the liquid part from the solid part.