1. Food Preservation Ecosystems Unit, March 2, 2005

2. Food Preservation Techniques Throughout history, people have tried to alter the environment to prevent micro- organisms from spoiling their food. Egyptians salting geese (~2,000 BC)

3. Preserving food involves creating environments that microorganisms do not like. *Preservation Techniques: 1. Drying 2. Smoking 3. Salting 4. Pickling 5. Canning 6. Cold Temperatures

4. 1. Drying Drying is the oldest form of preserving food. It removes the moisture (water) in food. Meat is usually cut into very thin strips which helps it to dry faster.

5. Drying meat is still common today

6. 2. Smoking Chemicals in smoke help prevent the growth of micro- organisms. Food is both smoked and dried since smoking alone will not preserve food.

7. 3. Salting Salt draws out the moisture in food (especially meat). Before refrigeration, most meat was salted. Drying and salting cod in Newfoundland

8. 4. Pickling Pickling preserves food by placing it in either a brine (high salt solution) or in vinegar which is too acidic to allow micro-organisms to grow. Barrels of pickled meat were loaded onto ships for trade in the 1700s

9. 5. Canning Canning was first used in the late 1700s to provide unspoiled food for Napoleon's armies. Canning involves cooking fruit or vegetables and sealing them in air-tight, sterile jars. The jars/cans are then boiled to kill any remaining micro-organisms.

10. 6. Cold Temperatures Cold temperatures slow the growth of micro-organisms. Before the invention of refrigerators (mid 1800s) people kept their food cold with ice or snow. Some also used ice boxes or cold rooms. Oak Ice Box

11. *Modern Ways of Preserving Food: Deep Freezing Freeze Drying (quickly frozen in a vacuum) Irradiation (food exposed to low levels of radiation) Pasteurization of milk (high heat then cooled) Chemical additives (preservatives)