Steam-Pressure Canner Method

The Steam-Pressure canner is used to process foods under pressure. The temperature most often used is 240° (12 pounds pressure at altitudes above 2,000 ft). A pressure canner is the ONLY safe method for processing low-acid foods such as, vegetables, meat, poultry and fish. The high temperature achieved with pressure destroys spores of bacteria that cause botulism, as well as, other types of spoilage. Failure to use a pressure canner when process low- acid foods can result in botulism which is often fatal.

In order to steam-pressure can at home, you must have a pressure canner. Pressure canners come in many brands, sizes and styles. Most hold 7 quart jars but some are tall enough to double stack pints and process 14 pints at a time.

Some have dial gauges, which look similar to a clock with hands and must be watched closely during processing to make sure pressure is held steady, at the recommended level. The gauge on dial gauge canners should be checked annually for accuracy. We provide this free service at the Clay County Extension Center. Other style pressure canners have weighted gauges. This type gauge is semi-self-regulating. It jiggles or rocks a certain number of times per minute, to regulate the pressure. Be sure to follow your manufacturer’s instructions.

The style you choose is up to your personal preference. There are more weighted gauge canners available on the market today, than dial gauge canners. Most pressure canners have a gasket (rubber ring) in the lid to ensure a firm seal. With proper care the gasket should last many years, but should be replaced if stretched, cracked, or otherwise damaged. Most hardware stores have replacement gauges and gaskets.

Some people are fearful of pressure canners. You do need to follow the manufacturers recommendations, but by doing so, a pressure canner is a very safe piece of equipment. Never leave a pressurized canner unattended. Before each use, be sure the vent pipe is free of debris. Make sure your gasket, gauge, safety value, and weight are present and in good repair. When processing, make sure pressure never exceeds 20 pounds. When finished processing, turn off heat and allow canner to cool slowly and naturally. Do not jiggle weight. Do not run under cool water. After canner has cooled enough for the pressure to have dropped to zero, remove weight (open vent). NEVER open canner lid before removing weight. Allow steam to escape several minutes, before opening canner lid. Carefully tilt lid away from you, to avoid steam rushing in your face.

Some people are afraid pressure canners will explode. Pressure canners have a safety value. If proper procedures are not followed and pressure gets too high in the canner, the value will pop out. This will release the pressure in the canner, eliminating the possibility of the canner exploding.

Preparing the food and packing the jars is the same for boiling-water and pressure canning methods. Remember to remove air bubbles, using a plastic utensil, refill with liquid if necessary, before placing lid and ring on jars.

Pressure canners vary, so you must be familiar with your manufacturer’s instructions. The following are instructions for using pressure canners in general.

1. Place rack inside of pressure canner.
2. Add 2 - 3 inches of water. Heat to simmer.
3. Place jars on rack immediately after filling. Lock canner lid securely in place. Increase heat to medium-high setting until steam flows steadily from the petcock (air vent).
4. Exhaust steam from the canner for 10 minutes. This step is often forgotten or omitted. This step is necessary to drive all excess air from the canner.
5. Place weight on petcock. It will take approximately 5 minutes for canner to pressurize. After the gauge indicates recommended pressure is reached, gradually adjust heat to maintain pressure for the entire processing period. Begin timing processing at this point. Set timer for the recommended processing time.
NOTE: Altitude affects processing time, both in boiling-water and pressure canning. For altitudes of 2,000 feet, which most of Clay County is, increase the processing time 5 minutes for boiling-water methods. For pressure canning increase pressure to 12 pounds with a dial gauge and 15 pounds with a weighted gauge. If you would like a complete Altitude Chart with recommended adjustments, call the Clay County Extension Center.
6. After processing period is complete, turn off heat. Allow the canner to cool naturally. DO NOT remove the weighted gauge or open petcock until the canner has depressurized and returned to zero pressure. Remove gauge or open petcock. Let sit a few minutes, allowing steam to escape Carefully unlock lid and lift it off, being sure to tilt away from face, so steam will escape away from you. Let canner cool 10 minutes before removing jars.
7. Using a jar lifter, remove jars from canner. Set jars upright on a dry towel or cutting board, away from drafts, leaving 1 - 2 inches of space between jars. Allow to cool for 12 to 24 hours before checking seals.
8. When jars are completely cool, press the center of the lids. If it is concave and does not give to the touch, then remove the bands. Wash jars, rims and lids to remove any residue. Label as to contents and date. If a lid is not sealed, the product can be immediately reprocessed by reheating the contents, replacing the lid and reprocessing the full length of the recommended processing time. Reprocessing often causes an overcooked, mushy product. I recommend considering an alternative storage method for jars that did not seal, such as refrigerating or freezing.
9. Store sealed jars in cool, dry, dark place, for up to one year for optimum quality. Ideal storage temperature is 50 – 70°.

Below are answers to some common home canning questions.

Q – Why did the liquid in my jars drop?
A – Hot packing helps; Food packed too tightly; Air bubbles not removed; Fluctuation in temperature and pressure; Cooling too quickly

Q – Why did several jars fail to seal?
A – Not preparing lids correctly; Tightening rings too tightly; Not cleaning food particles and/or salt from rim of jars; Under or not processing food; Chips on rim of jars.

Q - Why does fruit /tomatoes float in jar?
A – Hot packing fruits helps; Food is lighter than the liquid it is packed in.

In summary, home canning is one of the most rewarding tasks you can do for you and your family. Making sure you follow recommended procedures and recipes is so very important.

Always use a pressure canner for low-acid foods. If you are afraid of pressure canners or do not own one but still want to put up low-acid foods, please freeze or dehydrate instead. At the Clay County Extension Center, we have a pressure canner available for loan, free of charge. This is a good way to use one, see if you like it, and hopefully in the future purchase one for yourself. Pickles, relishes, jams, jellies, preserves, fruits, salsas and tomatoes can be safely canned using the boiling-water method, but not low-acid foods.

The best place to find safe, tested recipes for jams and jellies is in the commercial fruit pectin boxes. Most people use commercial fruit pectin for jams and jellies to better ensure their product gels. The most popular brands are Sure•Jell (powdered pectin) and Certo (liquid pectin) but other companies also sell fruit pectin. Look in the food preservation aisle of your grocery, hardware, and discount stores. There are also fruit pectins formulated for low and no sugar preserves. These CAN NOT be used interchangeably with regular pection, but using the recipes in the box, you can successfully make low and no sugar jams and jellies. Recipes for cooked and uncooked (freezer jams) can be found in all commercial fruit pectin boxes.

We have free handouts on all methods of food preservation, available at the Clay County Extension Center. If you plan to go into canning and preserving, in a big way, I would suggest purchasing a thorough food preservation book like Ball Blue Book of Preserving or So Easy to Preserve.