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Methods of Food Preservation

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Presentation on theme: "Methods of Food Preservation"— Presentation transcript:

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)

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