How is ice cream made?

At home you can make ice-cream in the freezer or in an ice-cream maker but if you need to make thousands of litres a day, you need to use a different method.

This is what happens in an ice-cream factory:

* First the ingredients are weighed out and mixed together.

* Then the mix is pasteurised. This means it is heated to a high temperature to kill off any harmful bacteria.

* The mix is also homogenised. This means breaking down the fat globules in the milk or cream to make them smaller. Now the ice-cream will be smoother, will whip better and won't melt as easily.

* The mix is then left for at least four hours, usually overnight, to let the fat cool and form into crystals.

* Any flavours, fruit purees, or colours are added at this point.

* The mix is then pumped through a special barrel freezer which freezes some of the water in the ice-cream and whips air into it at the same time. Up to half the volume of ice-cream is air. Without it, the ice-cream would be like a frozen ice cube.

* Any fruits, nuts, sweets or biscuit bits are added to the semi-frozen mixture at this point.

* The ice cream is then packaged and put into a blast freezer at -30° to -40°C where more of the water in the ice-cream is frozen to make it harder.

http://news.bbc.co.uk/cbbcnews/hi/find_out/guides/tech/ice-cream/newsid_3634000/3634974.stm