NDSU Extension Service - Ramsey County


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From Garden to Jar

From Garden to Jar


          Home canning is on the upswing for many reasons – in response to higher grocery prices, increased fuel costs have many cutting back on trips to the grocery store, downtown in the job market and efforts by Americans to “go green”.  Add in the opportunity for creativity and satisfying the particular tastes of your family and the boxes of canning lids are practically flying off the store shelves.

          Home canning of food is both easy and complicated.  “Put food in jar, screw on lid, heat and enjoy” – that’s all there is right?   Each step in that seemingly simple process has many sub-steps and precautions to it.  Following are some of the more common questions from both beginning and experienced canners.

          If my recipe doesn't call for processing, do I need to do so?
Many recipes passed down through the years or found in older cookbooks do not include instructions for processing – sometimes because the expert canner who shared the recipe assumed everyone knew the next step was a trip to a water bath canner or a pressure canner.  Sometimes foods were prepared heated, sealed and stored without further processing.  Foods prepared in this manner present a serious health risk.   To avoid the risk of food spoilage, all high acid foods must be processed in a water bath canner or pressure canner and all low acid foods in a pressure canner.

          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. Also, the jar may not seal properly because there will not be enough processing time to drive all the air out of the jar.

          Is it all right to reuse jar fittings (lids and bands)?
Lids should not be used a second time since the sealing compound becomes indented by the first use, preventing another airtight seal. Screw bands may be reused unless they are badly rusted or the top edge is pried up which would prevent a proper seal.

          Why do the undersides of metal lids sometimes discolor?
Natural compounds in some foods, particularly acids, corrode metal and make a dark deposit on the underside of jar lids. This deposit on lids of sealed, properly processed canned foods is harmless.

          What causes jars to break in a canner?
Breakage can occur for several reasons: 1. Using commercial food jars rather than jars manufactured for home canning, 2. Using jars that have hairline cracks, 3. Putting jars directly on bottom of canner instead of on a rack, 4. Putting hot food in cold jars, or 5. Putting jars of raw or unheated food directly into boiling water in the canner.\

          How can I remove scale or hard-water film from canning jars?
Soak jars for several hours in a solution containing 1 cup of vinegar and 1 gallon of water.

          Is it safe to can food without salt?
Yes. Salt is used for flavor only and is not necessary to prevent spoilage.

          Which vegetables expand instead of shrink during processing?
Corn, peas and lima beans are especially starchy and expand during processing. They need to be packed loosely to avoid broken jars and lids which do not seal.

          What causes corn to turn brown during processing?
This occurs most often when too high a temperature is used during the canning process which in turn caramelizes the sugar in the corn

          For the latest, safest and most accurate information on home canning, contact our office at #662-7027 or stop in the Ramsey County Extension Office on the second floor of the Ramsey County Courthouse, downtown Devils Lake.


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