Pressure Canning Details

Pressure canning is the only safe method for preserving low acid vegetables, meat, poultry, and fish. When preserving these foods, the only way to kill the botulism bacteria is by raising the temperature of the foods to 240oF. Make sure your canner is in good working order. Check the condition and placement of the gasket and safety plug (fuse). Make sure the vent is clean.

Generally speaking, select vegetables that are firm and ripe, but not overripe. For the best results, keep the time between harvesting and canning as short as possible. Wash or rinse the vegetables, but do not allow them to soak. Peel vegetables if necessary, remove seeds, etc. Avoid using bruised or damaged produce. Cut into serving sizes.

Make sure your jars are in excellent condition, with no nicks or cracks. Wash jars with hot soapy water and rinse thoroughly in hot water. Keep them hot until you use them to prevent breakage when they are placed in the canner.

Use new canning lids for each jar. Even though they are new, check them for dents, caps, or defects in the gasket. Place them in a shallow pan of simmering water.

Foods may be packed into jars while raw or hot. Raw-packing means adding uncooked food directly to the jar, then pouring boiling water over the product. In most cases raw food is packed tightly because of the shrinkage that occurs after the product cools.

For hot-packing, the product is heated to boiling or the product is cooked for a specified amount of time, packed into the jars while still hot, and filling the jars with boiling hot liquid. Hot-packed food is packed loosely because the food has already shrunk during the heating/cooking. When pressure canning, hot-packing the food yields better color and flavor compared to raw-packing.

If not hot-packed, most vegetables should be blanched before packing. This is a simple process. The prepared vegetable is dropped into briskly boiling water for a certain period of time (see the table below), usually just few minutes, then scooped out of the boiling water and dropped into ice water. The boiling water stops the enzyme changes in the vegetable pieces, and the quick dip in ice water stops the cooking process.

After packing the product and covering with boiling liquid, work out any air bubbles that remain by using a plastic spatula or other utensil that will not scratch the jar. If allowed to remain in the product, these bubbles will rise during processing, affecting the amount of head room. Too much head room left can result in an insufficient vacuum, which would then allow the growth of dangerous bacteria. Most vegetables require only a half-inch of head room. Measure your jars to make sure of the correct depth.

Wipe the rim of the jar with a clean, damp cloth; center the lid onto the jar, lightly screw on the metal ring/band. Make sure the rings are the correct shape, and do not over-tighten them. Air must be allowed to escape during the processing.

Prepare the pressure canner with 2 to 3 inches of clean, hot water. It is handy to have additional boiling water on the side in case it is needed to maintain the water level after the canner is brought to a boil.

Put the jars in the canner on the rack and so that they do not touch each other. Put the lid in place and turn the heat to high. Leave the vent port open until all the air is exhausted. This can take about 10 minutes. When the cooker has been properly vented, place the weight onto the port.

Do not begin the processing timing until the weight jiggles or, if equipped, the gauge reads the correct pressure. If processing above 2,000 in altitude, please use the below. Also, notice the chart below is divided between weighted gauges and dial gauges. Follow the adjustments on the chart for your altitude and type of canner.

 

After the processing time, remove the canner from the heating element and let it cool without interference. This time is essential for both your safety and the food’s. When the pressure has dropped to normal, carefully open the vent port and wait another 10 minutes.

Open and remove the lid, being careful to not get scalded by any residual steam. Remove the jars from the canner and place onto a rack or towel, with at least an inch of space between them. Do not tighten the rings; this could release the seal if the ring is slightly out of shape. After the jars have cooled, test for a good seal by pressing the center of the lid. If the lid flexes, a seal has not been achieved and the jar will need to be reprocessed or refrigerated and eaten within a few days.

If reprocessing is needed, open the jar and check the rim for cracks or chips. Put the food in a new jar if needed. Always use a new lid. Reprocess as before. Label the jar as reprocessed and consume it first.

Remove the rings/bands to prevent them from rusting onto the jars. Wipe any residue from the jars. Make sure to label them with the date and contents. If processing multiple batches, lot numbers may be assigned, too. Sealed jars should be stored in a cool, dark place – preferably 40o to 60oF [5o to 15oC]. Most foods kept this way will keep for up to a year. Although still safe after a year, home-canned products’ quality and nutritional value may have diminished.

NOTE: Any food whose odor or appearance is questionable when the jar is opened should be discarded at once. Never test it by tasting it. Botulism can be deadly!

Bulging lids, leaking jars, and mold are all signs the food has spoiled. Avoid touching spoiled foodstuffs. Seal jar and all in a heavy garbage bag and dispose of it in a landfill. If you desire to keep the jar and ring/band (if it was left in place), after carefully emptying the jar of the food into the trash and sealing it, the jar and ring can be washed, boiled for thirty minutes in water that is one inch deeper than the jar is tall, make sure jar is full of water, too.

Clean all items that came into contact with the spoiled food with a solution of one part unscented bleach to five parts clean water.

The chart below gives the required preparation for each vegetable as well as processing time and pressure.

Remember, processing time does not begin until the correct pressure has been achieved. If at any time during the process the pressure falls below the required amount, the canner must be brought back up to the correct pressure and the processing time started over. Double check the altitude chart above, please remember to make the adjustments noted. Also, remember the difference in pressure for processing with a canner that uses a weight versus one that has a gauge.

Meat, and poultry are included in the chart. The process is the same as for pressure canning vegetables, except meat is always cooked before processing and hot-packed. Canning is not recommended for veal, fish, shellfish, or ground meats, unless combined in a sauce, see recipes in the last section of this book.

 Pressure Canning Charts