august 2008 preservation from foukeffa.org written by teri micke ag student texas a&m ga ag ed...
TRANSCRIPT
August 2008
PRESERVATIONPRESERVATION
From foukeffa.org
Written by Teri Micke
Ag Student Texas A&M
GA Ag Ed Curriculum Office
To accompany the Georgia Agriculture Education Curriculum Lesson 02471-21.2
June, 2002
August 2008
WHAT IS PRESERVATION?
WHAT IS PRESERVATION?
• the treatment of food to keep it from spoiling
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PALATABLEPALATABLE
• an agreeable taste and/or texture
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CONDUCTIONCONDUCTION
• heating through direct contact
• example: roasting marshmallows, grilling hamburgers on stove top
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CONVECTIONCONVECTION
• heating through water or air
• example: boiling water, using oven
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RADIATIONRADIATION
• heated through electromagnetic spectrum
• example: microwave
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PASTEURIZATIONPASTEURIZATION
• destroy pathogenic microorganisms but not spoilage microorganisms
• example: milk
August 2008
TYPES OF PRESERVATION
TYPES OF PRESERVATION
1. canning - around for over 200 yrs
2 ways
a. hot fill - heated before put in can
b. canner’s brine - liquid (sugar/salt mix) added
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2. Refrigeration - above freezing point 28 to 65 degrees F; short term storage
3. Freezing - actually freezing the water in the food
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4. Drying a. mechanical: heat (sunlight),
wind, smoke/heat
examples: grapes to raisins, meat to jerky
b. freeze drying: used by astronauts, just add water
examples: milk replacers
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c. chemical drying
add salt and sugar
example: ham
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5. Fermentation - involves microorganisms (yeast, mold, bacteria)
2 ways:
a. aerobic: with air
b. anaerobic: without air
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6. Irradiation: expose food to ionizing radiation like x-rays, makes food sterile
veg/spices easy to treat
meats hard to do, but they are using on poultry
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7. Food Additives
examples:
Salt
Na or Ca - inhibit mold
Sorbic acid - inhibit yeast/mold, used in cheese and fruit drinks
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Benzoic acid/sodium benzoate - candied products
BHT/BHA - preserve fat in meat
Citric acid/tartaric acid - antioxidants (traps oxygen)
August 2008
WHAT HAPPENS WHEN FOOD FREEZES??
WHAT HAPPENS WHEN FOOD FREEZES??
Example: Tomato
the water in the tomato freezes and forms ice crystals which act like sharp pieces of glass and puncture cells, the slower the freezing the larger the crystals
August 2008
WHAT IS FREEZER BURN?
WHAT IS FREEZER BURN?
• it’s the loss of water from the frozen food