1986
HE-132
Safe
Home Canning of Low-Acid Vegetables
William D. Evers and April C. Mason, Extension Foods and Nutrition Specialists
There is only one safe way to safely can most vegetables at home—in a pressure canner. This special piece of canning equipment is vital for a safe product. Using a pressure canner properly will reduce the chance of food spoilage and insure a safe, quality product. For more information on pressure canners see HE 129, “Using and Caring for Your Pressure Canner,” available from your county Extension office.
Botulism, a deadly form of food poisoning, can occur when low-acid vegetables are canned improperly. The food poison is a toxin produced by the bacteria, Clostridium botulinum. The toxin often is fatal. The organism is extremely resistant to heat, and it grows without oxygen in low-acid canned foods. Unfortunately, the resulting spoilage is often difficult to detect. The deadly toxin may be produced before you can see any sign of spoilage. As a precaution, never taste home canned non-acid vegetables before boiling them 10 to 20 minutes. This gives you a margin of safety in case your pressure canner’s gauge is faulty or you did not follow the canning procedure exactly.
General Procedures
Selecting Vegetables:
Quality and Quantity
Choose only young, tender vegetables. Can them before they lose their freshness. If you must store them, keep in a cool, airy place. If you buy vegetables to can, be sure you get young, high quality produce.
For best quality canned products, use vegetables that are free from bruises or blemishes. Sort them for size and ripeness because they cook more evenly that way.
Your canning will be much easier and more efficient if you work with quantities you can process at one time. The number of jars of canned
food you can get from a given quantity of fresh vegetables depends on the quality, variety, maturity, and size of the vegetables, and on whether they are packed in jars in their raw state (cold pack) or cooked and softened first (hot pack). Table 1 provides information on the measure and weight of various vegetables, on approximately how many pounds will fill one quart jar, and on approximately how many quart jars you will need to can one bushel. If you are using pint jars, divide the number of pounds needed to fill a single jar by 2, and double the number of jars needed to can a single bushel.
Washing
Soil contains some of the hardest to kill bacteria, so wash all vegetables thoroughly, whether they are to be pared or not. Wash small amounts at a time under running water or through several changes of water. Lift the food out of the water each time so soil will not settle back on the food. Rinse your pan thoroughly between washings. Do not soak vegetables; they may lose their flavor and food value if you do. And be sure to handle vegetables gently to avoid bruising them.
Filling Containers
Before you fill canning jars, wash them in hot, soapy water and rinse well. Fill clean, hot jars one at a time with raw or hot vegetables. Follow the directions given in this publication. If necessary, reheat jars after filling by immersing them in a canning kettle full of hot water.
Most raw vegetables can be packed tightly into the container because they shrink during processing. However, a few—such as corn, lima beans, and peas—should be packed loosely because they expand. Pack hot foods loosely. Hot foods should be at or near boiling temperature when they are packed.
Purdue University Cooperative Extension Service, West Lafayette, IN 47907