ZIMSEC O Level Combined Science Notes: Methods of food Preservation
| Method | Details | Example |
|---|---|---|
| Dehydration/Drying | The microorganisms responsible for food require water for their metabolic functions. Drying prevents respiration and causes cells to shrink it is used to preserve vegetables, fruit, milk and meat (biltong). |  |
| Canning | The food is heated/cooked and then sealed. The microorganisms responsible for going bad are killed in the process and the tinned cans also lack oxygen. This gives the food a longer shelf life. It is used with meat, fruit, vegetables and dairy products. |  |
| Salting | Salting food kills the organisms that cause food to go bad. It is used with fish (kapenta) and meat | |
| Sugaring | Sugar causes the cells to shrink and prevents the growth of bacteria and fungi. For example jam. | |
| Pickling | Some of the organisms cannot survive a low pH. Some types of foods can thus be preserved in acids for example using vinegar (acetic acid) for example vegetables |  |
| Smoking | Certain wood smokes produce anti-bacterial and fungicidal compounds which are used to treat meats and fish. For example apple wood is used on trout fish. |  |
| Refridgeration | Cooling/Freezing food prevents the growth of bacteria and fungus in all foods. |
To access more topics go to the Combined Science Notes page
