Food Preservation: Overview of Methodologies By Lauren Woodliff for the CTAE Resource Network

Drying  Oldest known method; 12,000 B.C.  Sun, Wind & Fire  Fire also used to dry fruits, vegetables & herbs  Modern day examples of dried preserved food:  Beef Jerky  Sun Dried Tomatoes

Pickling & Fermenting Pickling  Preserve foods in vinegar or other organic acid  Lower pH inhibit bacteria and microorganisms Fermenting  Helpful microorganisms lower pH  Can make food more nutritious Examples:  Sauerkraut  Yogurt  Wine  Most Cheeses

Jam & Jelly  Sugar reduces the water content  Lower pH  Cooked during the process All of the above inhibit microorganism growth

Curing  Curing:  Salt reduces water content  The addition of Nitrites and Nitrates inhibit the bacteria Clostridium botulinum, which causes botulism  Smoked foods are also cured

Freezing & Refrigeration Freezing  Zero degrees Fahrenheit  Easiest, least time-consuming and most convenient method Refrigeration  40 degrees Fahrenheit or below  Prolongs shelf life of food  Slows growth of most microorganisms but does not kill or inhibit growth  Food will eventually spoil

Canning  Extreme heating  Oxygen is driven out  Creates a vacuum seal  Two methods:  Water Boiling Canning  Pressure Canning  The method that should be used depends on the type of food and its pH

Boiling Water Canning  Foods with pH below 4.6, high acid foods  212 degrees Fahrenheit  Kills most food spoiling/illness causing bacteria and microorganisms except Clostridium botulinum (cause of Botulism)

Pressure Canning  Foods with ph above 4.6, low acid foods  240 degrees Fahrenheit  Only pressure canning can reach temperatures this high  Kills the bacteria, Clostridium botulinum

Summarize and Discuss  Why is it important to preserve food for later use, especially before modern day packaging and refrigeration?  Why is important to choose the right method for different foods?  What are some of the factors that determine what method to use?  Think about the food that you eat on a daily basis that have been preserved using the methods that have been discussed.