Page 286 - Primary Six Notes

Preserving milk

Milk is a good environment for bacteria to multiply. It should

therefore be preserved for future use otherwise it will go bad.

Methods of preserving milk

Sterilization / pasteurization

 This means killing germs in milk by maximum boiling fol-

lowed by cooling and boiling.

 The heating kills germs and quick cooling prevents bacteria

from entering milk and multiplying.

 This method was named after Louis Pasteur, a French Scien-

tist who discovered that milk goes bad because of bacteria.

Refrigeration

This means putting milk in a refrigerator where germs can not

easily and quickly multiply because of very low temperature.

Boiling

This means killing germs by boiling milk from time to time.

Homogenizing

This is a way of treating milk so that fats are broken and then

cream is mixed with the rest.

Homogenizing is not a way of preserving milk.