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FREQUENTLY ASKED QUESTIONS   CANNING BASICS

Question 11. Is it safe to use canning recipes found on the web or passed down from family?

Oftentimes canning problems arise because of outdated recipes. Family recipes and many found online may be seriously incorrect. Guidelines have changed, testing has changed, and agriculture is different than it was years ago. Always use reliable sources that offer current, research-tested procedures, recipes, and timetables. Such information is available on this Presto website. In addition, the National Center for Home Food Preservation and your local Cooperative Extension Service are also reliable sources of home canning information and established processing procedures. Canning recipes must be scientifically tested, which is vital to a safe and successful home canning project. Canning information published before 1994 may be incorrect and could pose a serious health risk.

Question 22. Do I really need to leave a certain amount of headspace in the jar?

Yes. Leaving the specified amount of headspace in a jar is important to assure a vacuum seal. If too little headspace is allowed, the food may expand and bubble out when air is being forced out from under the lid during processing. The bubbling food may leave a deposit on the rim of the jar or the seal of the lid and prevent the jar from sealing properly. If too much headspace is allowed, the food at the top is likely to discolor. More importantly, the jar may not seal properly because there will not be enough processing time to drive all the air out of the jar.

Question 33. How do I know if the screw band is tight enough?

Do not use undue exertion. Adjust two-piece vacuum caps by screwing the bands down evenly and firmly until a point of resistance is met, or fingertip-tight. Two-piece vacuum caps seal by the cooling of the contents, not through the pressure of the screw band on the lid. During processing, the flexible metal lid permits air to be exhausted from the jar.

Question 44. Is it necessary to vent my pressure canner before processing?

Yes. It is vitally important to allow steam to escape from the canner for 10 minutes before placing the pressure regulator on the vent pipe. This ensures that all air is vented (exhausted) from the canner as well as the jars. If the air is not exhausted, the inside temperature may not correspond to the pressure on the gauge. It also eliminates any air pockets in the jars of food that would cause an uneven heat treatment to occur.

Question 55. How do I stack a second layer of jars?

It may be necessary to double-deck pint or half-pint jars to reach the maximum capacity of your canner. It is recommended that you stagger the jars by placing one jar on top of two. The canning rack which accompanied your Pressure Canner must be placed on the bottom of the canner to prevent jar breakage. It is not necessary to use a rack between the layers of jars. However, if you wish to do so, go to Parts & Service and search for your canner’s accessories to order a rack.

Question 66. Is there a problem with canning overripe food?

Yes. Flat sour is a type of food spoilage that is caused by canning overripe food or allowing precooked foods to stand in the jar too long before processing. Use ripe or slightly underripe food and properly process, cool, and store. Flat sour shows no indication of spoilage until the jar is opened.

Question 77. Do I use the same time and pressure when processing less than a full load in the canner?

Yes. The processing pressure and time, as well as water in the canner must be the same regardless of the number of jars being processed. The venting (exhausting) time also remains the same.

Question 88. On my Weighted Gauge Canner with 3-piece adjustable regulator, why is it important for the pressure regulator to maintain a slow, steady rocking motion?

Question 8

The adjustable pressure regulator is designed to maintain the appropriate pressure inside the canner when the regulator is rocking in a slow and steady motion. A loud, annoying, and vigorously rocking regulator is the result of the heat source being too high and may result in the canner boiling dry. In addition, it may cause liquid loss in your jars of food. It is essential to understand what a slow, steady rocking motion looks and sounds like. Click the video link for reference.

Question 99. Is it better to overprocess food than underprocess?

It is better to overprocess. Underprocessing may result in spoilage and unsafe food.

Question 1010. During processing the pressure dropped below the recommended amount. Is that a problem?

Yes. If the pressure drops, it needs to be restored to the recommended level, and the processing time must start from the beginning.

Question 1111. Water is present on the lids when I remove the processed jars from the canner. Should I tilt the jar to remove the water?

No. The water will evaporate on the hot lid. Keep the jar upright when removing it from the canner. Tilting the jar could leave a deposit between the jar and the lid preventing the jar from sealing properly.

Question 1212. What causes corn to turn brown during processing?

Caramelization of the natural sugar in corn causes the brown color. This change can occur when canning super sweet varieties of corn. This color change is not harmful.

Question 1313. Is it safe to can fruits without sugar?

Yes. The sugar in syrup does not preserve the fruit, but it does improve flavor, help stabilize color, and retain the shape of the fruit. Fruit which has been canned without sugar will often turn brown when exposed to air just as fresh fruit does.

Question 1414. What causes beets to lose their color during processing?

It is not unusual for beets to lose some color vibrancy during processing. The best way to minimize the loss is to precook the beets leaving one inch of the stem and root intact. After cooking, slip off the skins and remove the stem and root. A more noticeable color loss or change in color may be due to the variety of beets used for canning. Two varieties of beets that retain color well are Ruby Queen and Detroit Red. Color loss may also result from water that is alkaline in nature.

Question 1515. When canning meat, why is it necessary to remove as much fat as possible before canning?

During processing, any fat that gets on the rim of the canning jar can prevent an airtight seal. Leaving excess fat on meat makes it easier for the fat to climb the sides of the jar and contaminate the seal.

 

Canning Index | Canning Introduction | Frequently Asked Questions | Pressure Canning Method
Boiling Water Method | Fruits | Tomatoes and Tomato Products | Vegetables | Meat, Game and Poultry
Fish and Seafood | Stock and Soup | Troubleshooting | Care and Maintenance| Pressure Canner Comparison Guide