PRESERVATION 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

WHAT IS PRESERVATION? the treatment of food to keep it from spoiling

PALATABLE an agreeable taste and/or texture

CONDUCTION heating through direct contact example: roasting marshmellows, grilling hamburgers on stove top

CONVECTION heating through water or air example: boiling water, using oven

RADIATION heated through electromagnetic spectrum example: microwave

PASTEURIZATION destroy pathogenic microorganisms but not spoilage microorganisms example: milk

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

2. Refrigeration - above freezing point 28 to 65 degrees F; short term storage 3. Freezing - actually freezing the water in the food

a. mechanical: heat (sunlight), wind, smoke/heat 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

c. chemical drying add salt and sugar example: ham

5. Fermentation - involves microorganisms (yeast, mold, bacteria) 2 ways: a. aerobic: with air b. anaerobic: without air

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

7. Food Additives examples: Salt Na or Ca - inhibit mold Sorbic acid - inhibit yeast/mold, used in cheese and fruit drinks

Benzoic acid/sodium benzoate - candied products BHT/BHA - preserve fat in meat Citric acid/tartaric acid - antioxidants (traps oxygen)

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

WHAT IS FREEZER BURN? it’s the loss of water from the frozen food