Processing of milk

How to pasteurise whole milk

Heat to 72 degrees for 15 seconds

Cool rapidly to 10 degrees

Keep refrigerated

How to pasteurise milk for semi-skimmed/ skimmed milk

Heat to 72 degrees for 15 seconds

Cool rapidly to 10 degrees

Remove some/ all of the cream

Keep refrigerated

Homogenised milk meaning

Homogenised milk is milk that has been processed mechanically to break down fat globules into much smaller particles, preventing them from separating and rising to the top as a layer of cream. This creates a stable emulsion with a uniform, creamy texture throughout.

Why do we pasteurise milk?

To kill some spoilage and pathogenic bacteria, extending its shelf life.

How to sterilise milk

Homogenised

Bottled and sealed

Heated to 110 degrees for 30 minutes

Why do we sterilise milk?

Destroys most bacteria, extends shelf life for longer than pasteurised milk.

UHT ‘Long Life’ milk

Heated to 132 - 140 degrees for 1 second

Cooled rapidly

Packaged

Why do we ultra heat treat milk?

It destroys all bacteria, giving it a very long shelf life at room temperature if unopened.

Evaporated milk

Water is evaporated off

Milk is homogenised and sealed in cans

Then sterilised at 115 - 120 degrees for 10 minutes

Why do we make evaporated milk?

Most bacteria destroyed by heat and more concentrated conditions with lower water availability, so they can’t grow. Milk is lighter and takes up less space.

Condensed milk

Evaporated milk which is canned, but not sterilised. Lots of extra sugar is added.

Why do we dry milk?

No water therefore bacteria can‘t grow. Keeps for months, less bulky to store.

Why do we make condensed milk?

Heat treatment during evaporation kills bacteria, and the sugar prevents the growth of it. The milk is very thick and sweet.

Dried milk

Milk sprayed into hot chamber

Water evaporates leaving behind a powder.