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Saturday, 27 October 2012


Pasteurization means heating food to a certain temperature for some time followed by rapid cooling.  Heating at such high enough temperature kills most bacteria.  However, it does not affect the taste and nutritional value of the food.

On-the-Farm Milk Pasteurization


Smoking is the process of drying food with smoke for a long period of time.  This method is mainly used for fish, meat and fruit such as banana.  The drying effects of smoke and the chemicals produced from the smoke help to preserve the food.


As food is heated and cooked, the heat kills the microorganisms.  Boiling kills most bacteria.  However, those not affected by heat will grow when the conditions are suitable.

Monday, 22 October 2012

Cooling and Freezing

Cooling and Freezing are the most common forms of food preservation.  Cooling slows down the action of microorganisms, thus it takes longer to spoil.  It allows fruit from different parts of the world to appear on our supermarket shelves.  At freezing temperature, microorganisms become inactive, thus food cannot spoil when it is frozen.

Vacuum Packing

Vacuum packing keeps food by sucking air out from its packaging.  Food is thus prevented from spoiling because there is no air.

Vacuum packing is commonly used for storing nuts, sliced fish, pickled and dried fruit.


Salting, is a age-old way of preserving food.  The salt draws out moisture and prevents microorganisms from growing.  In this process, food such as fresh fish are gutted, washed and coarse salt is rubbed into it.


A lot of food is preserved by drying under the sun.  Drying removes most water from food.  Most bacteria die or become inactive when the food is dried.

Anchovies and dried chillies are examples of dried food.

A lot of fruit such as raisins, guavas and papayas can be eaten dried.

Saturday, 20 October 2012


Pickling food in vinegar or other acids, makes it difficult for microorganisms to live.  Commonly pickled food include onions, parkias, soya beans and chillies.

Sugar can also be used in pickling fruits such as nutmegs, mangoes and cherries.  The concentrated sugar solution used draws water from the fruit, thus preventing the growth of microorganisms.

Friday, 19 October 2012

Bottling and Canning

Bottling and canning are processes of preserving food by heating and then sealing it in an airtight container.  The food is boiled to kill microorganisms and then sealed to prevent other microorganisms from getting in.

Canned Food

Bottling Food

Let's watch how the canned sardine are made

Bottling process