1. Methods of Food Preservation
Intro to Agriculture AAEC – Paradise Valley Spring 2015

2. What is Food Preservation?
Food preservation is used to keep food from spoiling

3. Food becomes unsafe to eat
Effects of Spoilage
Food becomes unsafe to eat
Taste, smell, color, and consistency may change

4. Microbes: bacteria and other micro-organisms
Causes of Spoilage
Microbes: bacteria and other micro-organisms
Botulism, salmonella, e. coli are types of bacterial microbes
Molds (on breads or cheese) are fungi-caused spoilage
Chemicals- i.e. pesticides, spilled fuel
Insects- eat on the food material
Objects- fragments of the packaging material (glass, metal or plastic)

5. Preventing Spoilage
Must keep food from coming into contact with the causes of spoilage. Involves the following:
Proper storage
Protection from contamination
removal of moisture (to slow microbe growth and spoilage)
Use of temperature extremes (Slow or prevent spoilage)
Heating food destroys most microbes
Near-freezing temperatures slow microbe activity
Below-freezing temps stop microbe growth

6. Methods of Food Preservation
Methods must retain flavor and identity
Methods include:
Refrigeration
Freezing
Canning
Pasteurization
Irradiation
Aseptic Packaging
Drying
Salting
Fermenting
Pickling

7. Refrigeration
Short term method
Spoilage is slowed
Used with fresh fruits, vegetables, dairy products and meats
Most refrigeration is between degrees F

8. Freezing
Causes the water in foods to freeze
Temperatures should be -30 degrees
Works well with vegetables and meats (proper preparation
helps foods to retain
natural color and
flavor)

9. Canning
Placing the food into a container, heating to kill any microbes, and then sealing
Canned goods last up to a few years
Used with many vegetables and a few years

10. Pasteurization Most widely used with milk and fruit juice
Involves heating the food and holding it at a set temp. long enough to kill any microbes present
Ultrahigh-temperature
pasteurization (UHTP)
now being used with
some milk – allows milk
to be stored at room
temp. for a few weeks

11. Irradiation
Use of radiation to kill microbes in the food
Used only on a few foods
Gaining acceptance as a method to prevent spoilage

12. Aseptic Packaging Involves sterilizing the food and its packaging
New method of preservation
Often used with meats

13. Drying Most likely the oldest method of food preservation
Attempts to remove all traces of moisture so that microbes cannot live
Modern methods include freeze-drying
Food that can be dehydrated include
Meats
Vegetables
Fruits
Milk

14. Salting Use large amounts of salt to remove moisture from foods
Disadvantages
High concentration
of salt in food leads
to health problems
Palatability of salted
foods is poor

15. Fermenting/Pickling Pickling Fermentation
Involves changing the pH below the level of microbes- usually less than
Pickling uses vinegar (acetic acid) to lower the pH, and salt (to dehydrate the microbes)
Fermentation
Involves the conversion of complex sugars into simple compounds
Uses certain yeasts and beneficial microbes to secrete Enzymes and start the fermented process

16. Food that are fermented or pickled include :
wines (F)
bread (F)
cheese (F)
Sauerkraut (F)
Pickles (p)