August 2008 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 June, 2002
August 2008 WHAT IS PRESERVATION? the treatment of food to keep it from spoiling
August 2008 PALATABLE an agreeable taste and/or texture
August 2008 CONDUCTION heating through direct contact example: roasting marshmallows, grilling hamburgers on stove top
August 2008 CONVECTION heating through water or air example: boiling water, using oven
August 2008 RADIATION heated through electromagnetic spectrum example: microwave
August 2008 PASTEURIZATION destroy pathogenic microorganisms but not spoilage microorganisms example: milk
August 2008 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
August Refrigeration - above freezing point 28 to 65 degrees F; short term storage 3. Freezing - actually freezing the water in the food
August 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
August 2008 c. chemical drying add salt and sugar example: ham
August Fermentation - involves microorganisms (yeast, mold, bacteria) 2 ways: a. aerobic: with air b. anaerobic: without air
August 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
August Food Additives examples: Salt Na or Ca - inhibit mold Sorbic acid - inhibit yeast/mold, used in cheese and fruit drinks
August 2008 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?? 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? it’s the loss of water from the frozen food