Food Preservation Flashcards
Freezing
Reduces temperature of food- Micro organisms inactivated.
Bacteria cannot grow
Changes water in food to ice
THAWED FOOD SHOULDN’T BE REFROSTED
Temperature for freezing food
-18°C to -30°C.
Different ways of freezing
Quick freezing
Slow freezing
Blast freezing
Quick freezing
Small ice crystals form
Keeps food firm
Slow freezing
Large ice crystals form
Nutrients lost when food is thawed
Blast freezing
Commercial
-30°
Best method
Cell walls not damaged
Guidelines for freezing
Choose good quality fresh food Chill food before Use fast freeze section of the freezer Open-freeze food will stick together Usable quantity Label all packages Allow air circulation between packages
Advantages of freezers
Food stored in bulk and stored
Saves money
Food available off season
Retains colour flavour and texture
Canning
Bacteria destroyed by heat and food then kept in airtight cans.
Buying canned food
Avoid rusted or dented cans
Read labels
Check date
Examples of canned food
Fish un brine or oil
Fruit in syrup
Drying
Heat removes water from food
This prevents micro-organisms from growing due to lack of moisture.
Irradiation
Energy waves passed through food.
Micro-organisms killed and food keeps for a long time.
Effects of freezing on food value
Foods don’t lose vitamins or minerals
Effect of canning on food value
Vitamins destroyed
