Chapter 20 - Food Preservation Flashcards
Uses for pressure canning
Vegetables, meats, low-acid foods (above 4.5 pH) that have potential to carry Clostridium botulinum & its heat-resistant pores
Uses of water bath canning
▫High-acid foods below 4.5 pH – sufficiently acidic enough to prevent the growth of Clostridium botulinum
▫Fruits, tomatoes, pickles
Pressure canning process
Processed under pressure (pressure cooker) to control the processing temperature; 240° to destroy bacteria
Water bath canning process characteristics
Time required in bath depends on the size of jar, type of food & elevation
▫Hydrogen swells
How does drying kill microorganisms
if the moisture level reaches low enough levels to kill microorganisms
How is dehydration accomplished
▫Mild heating & evaporation
3 methods to avoid color changes during dehydration
oSulfuring
oBlanching
dip in acidic juice to avoid color changes.
Sulfuring
expose cut fruit to smoke from burning sulfur flowers; apricots
Blanching purpose in dehydration
minimizes color changes in dried vegetables.
What fruits benefit from being dipped in acidic juice to avoid color changes during dehydration
oApples & bananas
When does Maillard reaction occur during dehydration
when moisture level drops from 20 to 15%
Four classes of freezing
oPerishable raw foods
oPerishable heated or cooked foods
oSemi-perishable foods
oNon-perishable foods
3 benefits of freezing
- Convenience
- Quality
- Can be stored up to 6 months, some 12
Possible negative of freezing
Altered textures
4 types of commercial freezing
- Sharp freezing
- Air-blast freezing
- Indirect contact freezing
- Immersion freezing
