Methods of Food Preservation Intro to Agriculture AAEC

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

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

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

Causes of Spoilage �Microbes: bacteria and other microorganisms �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)

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

Methods of Food Preservation � Methods 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. must retain flavor and identity include: Refrigeration Freezing Canning Pasteurization Irradiation Aseptic Packaging Drying Salting Fermenting Pickling

Refrigeration �Short term method �Spoilage is slowed �Used with fresh fruits, vegetables, dairy products and meats �Most refrigeration is between 36 -40 degrees F

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)

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

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

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

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

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

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

Fermenting/Pickling � Involves changing the p. H below the level of microbesusually less than 4. 2 -4. 8 � Pickling uses vinegar (acetic acid) to lower the p. H, 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

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