What actually happens to milk during pasteurisation

It starts with heat.

Pasteurisation is, at its simplest, a way of heating milk to a set temperature for a set time, then cooling it again. The point is to kill off the bacteria that could make people ill. On that level, it does exactly what it sets out to do.

But milk is not an inert liquid. It is full of living things: enzymes, delicate proteins, the structures that give raw milk its character. Heat does not discriminate. Alongside the bacteria, some of that living quality changes too. The milk becomes more uniform, more stable, easier to move around at scale. It also becomes a little further from what it was when it left the animal.

None of this is hidden. It is simply rarely talked about, because for most of us milk is just milk. It arrives in a carton and we do not think about the journey.

Which is the part worth sitting with. Not whether pasteurisation is right or wrong, but how much of our food has been quietly reshaped to suit a system, and how seldom we stop to notice.