K-State Research and Extension Cottonwood District

Useful Canning Information

Only use professionally tested canning recipes and follow the recipes exactly, altering recipes can affect the pH level and make the food unsafe when canned. Even an extra 1/4 cup of onions or peppers in your canned salsa recipe can make it unsafe for your family to eat.

Canning Foods

Process Adjustments at High Altitudes
Reliable, tested recipes are written with processing instructions for sea level locations. Instructions to adjust for altitude are either within the instructions or in the general information. Using the process time for canning food at sea level may result in spoilage if you live at altitudes of 1,000 feet or more. Water boils at lower temperatures as altitude increases. Lower boiling temperatures are less effective for killing bacteria. An increase of the process time or canner pressure compensates for lower boiling temperatures. If you do not know the altitude, contact your local research and extension agent or a local district conservationist with the Natural Resources Conservation Service. Click the map to find your custom elevation.

Acceptable Canning Methods

Pressure canning for meat, poultry, seafood, and vegetables (low acid foods); utilizing United States Department of Agriculture (USDA) guidelines for pressure and time. Boiling-water canner for acid foods, such as fruits, pickles, sauerkraut, jams, jellies, mar­malades, fruit butter, and properly acidified tomatoes and figs (acidified to pH of 4.6 or lower with lemon juice, vinegar, or citric acid); utilizing USDA guidelines for time.

Canning Materials Recommended

Mason-type, threaded, home-canning jars with matching self-sealing lids are the only choice, and must be used for low-acid foods that are pressure canned. (Use Ball lids on Ball jars; Kerr lids on Kerr jars, etc.)

Use only new, common, self-sealing lids (flat metal lid held in place by a metal screw band during processing); removal of screw bands is permitted before storage of canned goods. (For exhibit purposes, replace the screw band so the flat lid will remain sealed during transportation and judging.)

Modern pressure canner with accurate dial gauge or weighted gauge. Pressure cookers not designed for pressure canning should not be used.

After cooling jars for 12 to 24 hours, remove screw bands and test seals with following options: Concave lid (curved down slightly in center); the lid should not spring up when pressed in the center; tapping the lid with a spoon will produce a ringing sound.

Non-Acceptable Canning Methods

Non-Acceptable Canning Methods

  • Steam canning
  • Open kettle canning
  • Microwave oven
  • Conventional or convection ovens, gas or electric
  • Slow cooker
  • Crock pot
  • Dishwasher
  • Canning powder or aspirin
  • The sun

Canning Materials Not Recommended

  • Mayonnaise-type (salad dressing) jars are not recommended for use with foods to be processed in a pressure canner because of excessive jar breakage. These jars should not be used for fair exhibits.
  • Other commercial jars with mouths that cannot be sealed with two-piece canning lids are not recommended for canning any food at home.
  • Jars with wire bails and glass caps.
  • One-piece zinc porcelain-lined caps.

Non-Acceptable Jar Seals

  • If lid is flat or bulging, it may not be sealed.
  • Unnatural odors, spurting liquids, rising air bubbles, unnatural color, cotton-like mold growth on top of food and underside of lid.
  • Paraffin or wax seals for sweet spreads.

Headspace Recommendations

  • ¼ inch for jams and jellies
  • ½ inch for fruits, tomatoes, pickles
  • 1 to 1¼ inch for low-acid foods

Store canned foods in a cool, dry place.

*Provided by K-State Rapid Response Center. May 2012. Revised by Karen Blakeslee, M.S., Extension Associate, K-State Department of Animal Sciences and Industry.