Let’s Get Ready to Preserve! Barbara Ingham Extension Food Scientist www.foodsafety.wisc.edu
Today’s topics: • Why preserve foods? • What are the basic food preservation guidelines? • What resources are available to help you get started on a successful food preservation season?
Why Preserve Foods? • Increase the shelf life of food. • Provide convenience. • Retain the nutritional value. • Improve how food tastes. • And because it’s fun!
Freezing, Drying, and Canning ……Which method will you choose? Our aim: safe, high quality food.
Cold Preservation • Set refrigerators to 32° - 40°F • Set home freezers to 0°F or below • Rapid freezing is best (less damage) • Freezing Fruits & Vegetables (B3278) • Proper packaging is critical for quality • Storage of frozen foods • Meats: 3 to 9 months • Fruits and vegetables: 1 year
Drying Foods • Air drying for herbs; Sun drying for fruits (ONLY!) • Controlled drying using an oven or dehydrator is best • Resource: www.uga.edu/nchfp/ • NEW! Recipes for making safe Jerky coming in August 2009 If water is not available, microbes can not grow
Heat Processing • Blanching • Short heating to stop enzymes, soften tissue, prevent color loss and remove air from tissue (vegetables before freezing/canning) • Pasteurization • Mild heat treatment designed to stop enzymes, to destroy growing bacteria, and to kill yeast and molds (milk & juice, and pickles & jam too) • Canning • High heat to destroy harmful microbes (especially pressure canning of meat, vegetables)
Two Types of Canning • Boiling Water Canning (212°F) – fruits and acid-added foods • Pressure Canning (240°F or above) – meats and vegetables (dial gauge or weighted gauge canners) • Remember…adjust for elevation!
How do we know which canning method to use? What is the pH (acidity) of the food? below pH 4.6 above Boiling Water Fruits, Pickles, Salsa Pressure Meat, Vegetables
What is ‘magic’ about pH 4.6? • IF the pH of the food is above 4.6 • IF there is no oxygen present • IF the temperature is warm Clostridium botulinumcan grow and produce TOXIN (botulism poisoning)
‘Recipe’ for Danger 1 Food, pH above 4.6 1 Vacuum sealed canning jar 1 Room @ standard temperature ADD: C. botulinumspores WAIT! You don’t need to add these, they are everywhere!
Conditions for neurotoxin production: • Spores of C. botulinum • No oxygen • pH greater than 4.6 Growing cells produce TOXIN
What does this mean for home canning? Foods with pH above 4.6 that you want to can: Process in a pressure canner to destroy spores of C. botulinum. Adding pressure increases temperature At sea level, water boils @ 212°F 10 pounds pressure (psi) - 240°F 15 pounds pressure (psi) - 250°F
Home Canning Resources • Using & Caring for a Pressure Canner(B2593) • Wisconsin Safe Food Preservation Series (2008): canning fruits, salsa, vegetables, meat, tomatoes, pickles & jam (www.foodsafety.wisc.edu) • Ball Blue Book www.freshpreserving.com/ • National Center for Home Food Preservation (www.uga.edu/nchfp/) *Resources MUST be from 1994 or later!
Botulism Strikes Spokane Mother, Two Children February 28, 2009 …The Associated Press reported that three people in Spokane, Washington, have become ill from botulism. The botulism apparently occurred from improper canning techniques used in home-canning of green beans vegetables from a private home garden. The woman was a nurse in her 30s with two children under ten. She became ill enough to be put on a ventilator; the children suffered milder symptoms. The incident was linked to difficult economic times.
What affects canning besides pH? • Pack method – raw pack or hot pack • Jar size – half-pints, pints or quarts • Elevation - affects boiling point of water Tomatoes, whole* Boiling water canner – 85 minutes Dial gauge canner - 25 min @ 11 psi Weighted gauge - 25 min @ 10 psi *hot pack, Qt. jars, 1,000 ft. p. 15 Tomatoes Tart & Tasty
Tips for Successful Canning • Properly pre-treat jars and lids • Fill jars with hot liquid (never cold!) • Leave the proper headspace • Boiling water canning: jars covered with 1-2 inches of boiling water at the start of processing • Pressure canning: vent canner for 10 minutes before pressurizing • Adjust for elevation
Don’t harm your family with these canning methods! • Boiling water canning of low-acid food • Open-kettle canning • Dishwasher canning • Oven canning
Don’t Forget • Process at the correct temperature (boiling water or pressure canner) • Follow an up-to-date, research tested recipe • Adjust for elevation *Note: darker areas on the state map have an elevation above 1,000 feet. Increase time when boiling water canning; increase pressure when pressure canning.
And now a word about…canners vs cookers Pressure canners and pressure cooker are NOT necessarily the same thing. • Pressure canners must hold at least 4 Quart jars and be able to regulate pressure at 5, 10, 15 pounds (psi). Pressure cookers are NOT recommended for home canning.
Will preserving food at home save you money? • Do you have a ready supply of fresh produce or meat? • Do you have canners and jars? • Do you have a working freezer with plenty of space? • Do you have the time….?
Food Preservation Updates • Add acid to tomato products! • Adjust for elevation when canning • Just because it sealed….it doesn’t mean it’s safe!!!!!! • Check pickle recipes for safety (even refrigerator pickles) • Safety of steam canners • A word about vacuum sealers
Getting Started…Equipment • Assemble Boiling Water and Pressure Canners • Check dial gauges and rubber gaskets Dial gauges must be checked each year! • Inspect jars, rims & lids • Purchase freezer containers • Clean your dehydrator
Getting Started…Produce • Start with tested varieties • Harvest at the proper stage of maturity • Discard diseased produce • Rapidly chill harvested produce
Getting Started…Recipes • Use ONLY up-to-date, research-tested recipes! • Don’t (necessarily) do what your Mother told you! • Current canning instructions date from 1994 or later. • Time to leave creativity behind!
Canning and Preserving for Special Diets • Choose recipes that don’t require sugar or salt for safety • Read the recipe carefully • Don’t choose your own substitutions see www.uga.edu/nchfp/