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Take precautions during canning process

The food preservation exhibits are among my favorites at the county fair. I love to see the glistening jars filled with delicious homemade delicacies.

While the results are beautiful, food preservation is rooted more in science than in art. Home canning can be a satisfying kitchen endeavor, but following the rules is important. This is not a place for cooking creativity.

Changing the makeup of a canning recipe can be harmful to your health and even deadly. Recipe alterations also can be costly in time, produce and money. You only should use scientifically tested recipes and USDA recommended procedures for home canning. Below are a few significant canning problems that should be avoided, and why.

Potentially deadly:

* Making up your own canning recipe: Without scientific testing, you will not know how long the product needs to be processed to be safe.

* Adding extra starch, flour or other thickener to recipe: This will change the rate of heat penetration into the product and can result in under processing.

* Adding extra onions, chili, bell pepper or other vegetables to salsa. The extra vegetables dilute the acidity, creating a low-acid product that might result in botulism poisoning.

* Using the oven instead of water bath for processing: The product will be under-processed since air is not as good a conductor of heat as water or steam. The jars also could explode.

* Not making altitude adjustments: Since boiling temperatures are lower at higher altitudes, the products will be under-processed.

* Not venting pressure cooker first: Lack of venting can result in air pockets that will not reach as high a temperature.

* Not having pressure canner dial gauges tested annually: If the gauge is inaccurate, the food could be under-processed.

* Failure to acidify canned tomatoes: Not all tomatoes have an adequate acid level, especially if the vine is dead. This can result in a low-acid product, which could become a risk for botulism poisoning. Current canning guidelines recommend adding citric acid, vinegar or lemon juice to ensure adequate acid levels.

* Letting food cool before processing in the recipes that call for "hot pack": The recommendations are based on the food being hot at the beginning of processing. Products could be under-processed.

* Cooling pressure canner under running water: Recommendations include the residual heat during the normal cool-down period as part of the processing time. Quick cooling will result in under processed food. It also could cause jars to break or liquid to be siphoned off the product.

Possibly hazardous, maybe deadly, but mostly resulting in economic loss:

* Use of mayonnaise jars: The jars could break, and it might be more difficult to obtain a good seal. Recycled jars only should be considered for boiling water bath canning.

* Use of paraffin on jams and preserves: Shrinkage or small air holes in the paraffin could allow mold to grow. Paraffin no longer is recommended.

* Cooling too slowly after removing from canner (for example, jars stacked close together): There are a group of harmless organisms called thermophiles that can survive canning. If jars are held hot for long periods, they can produce acid. This results in the defect known as "flat-sour" -- a harmless, but very undesirable flavor.

* Storing food longer than recommended: Lengthy or overly hot storage will decrease quality (color, texture, etc.) and some nutrients.

For more information on food safety when preserving food at home, check out the food preservation resources from Kansas State Research and Extension. We can test pressure canner dial gauges at the Ellis County Extension office (only the canner lid is needed). Please call ahead to be sure someone is available to test your gauge or be prepared to leave the canner lid.

I also will be glad to consult with you on your canning questions and problems. Call me at (785) 628-9430.

Linda Beech is a Kansas State University Research & Extension agent in Ellis County specializing in family and consumer sciences. lbeech@ksu.edu