Why food is processed and preserved
Fresh food spoils because microorganisms such as bacteria and fungi grow on it, and because natural enzymes break it down. Food processing technology uses methods that remove the conditions microbes need — warmth, moisture and air — so that food stays safe and lasts longer. Preservation reduces waste, lets food be transported over long distances, and keeps a supply available even when the food is out of season.
Common preservation methods
- Cooling and freezing slow down the growth of microorganisms by keeping food at a low temperature.
- Drying (dehydration) removes water, so microbes cannot grow. Dried anchovies (ikan bilis) keep for months.
- Salting and sugaring draw water out of microbes by osmosis, stopping their growth.
- Pickling keeps food in vinegar, creating acidic conditions that microbes dislike.
- Canning heats food to kill microbes, then seals it in an airtight container.
- Pasteurisation heats milk to kill harmful microbes without spoiling its taste.
Key idea
Every method works by removing one of the conditions microorganisms need to grow: take away warmth (freezing), water (drying, salting), air (vacuum packing) or a suitable pH (pickling).
Newer methods
Vacuum packing removes air (oxygen) so aerobic microbes cannot grow, while irradiation uses controlled radiation to kill microbes. Small amounts of chemical preservatives may also be added. Whichever method is used, good hygiene during processing is essential, because food that is already contaminated before it is sealed or frozen will still spoil. Preservation also lets Malaysia export foods such as canned pineapple and frozen seafood to distant markets without them going bad on the way.
Example
Traditional Malaysian ikan masin (salted fish) is preserved by salting and drying. The salt pulls water out of any microbes, and the dryness stops new ones growing — two methods working together.