🔄 Spray drying
Also known as: drying
Spray drying into powder.
Drying turns milk into powder. Spray drying is the most common method. First the milk is concentrated to about 50% solids. Then nozzles or a fast-spinning disc spray it as tiny droplets into a large chamber of hot air. The incoming air is heated to about 200–230 °C, but the water evaporates from the droplets almost instantly, so the powder does not overheat much. The outgoing air is about 75–85 °C. The powder is separated from the air in cyclones and filters.
Finished milk powder contains only about 3–4% moisture. That is why it keeps for a long time without a fridge, weighs little and is easy to transport. It is used in humanitarian aid, infant formula and baking. There is also roller drying, where milk is dried as a thin film on hot drums. It gives a “cooked” taste and is rarely used for milk today.
Nomads knew how to dry milk too. Marco Polo described how Mongol warriors took sun-dried skimmed milk on campaigns. Kurt, aaruul, chhurpi, jameed and kashk are still dried the same way, in sun and wind. Industrial production of milk powder began in the 19th century.
How it connects to milk
🔄 Spray drying → gives → 🧀 Milk powder → made from → 🥛 Milk
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Frequently asked questions
How is milk powder made?
The milk is first concentrated, then sprayed as fine droplets into a chamber of hot air. The water evaporates instantly, leaving a powder.
Why does milk powder keep so long?
It contains only a few per cent water, so germs have nowhere to grow. But heat and damp spoil the powder, so it is kept in a cool, dry place.