Home Canning

— Written By Susan Bugg

Since more families have started gardening this summer, interest in canning the “fruits of the harvest” has increased across North Carolina. Needless to say, food safety experts have learned much about the best canning practices since 1810, when the first canning techniques were developed. Individuals who practice canning often rely on recipes that have been handed down from past family generations or look to the internet for information on canning instructions. Unfortunately, many of these instructions and recipes are not considered safe food practices by today’s standards and should not be used. 

Upcoming canning classes: The NC Cooperative Extension will be offering basic information sessions as well as hands-on canning programs this summer. Lunch & Learn: Basics of Water Bath Canning (Tuesday, June 14th  from 12-1pm) and Basics of Pressure Canning (Tuesday, June 21st from 12-1pm). Both programs will be held at the Lucile Tatum Center, Gastonia. Registration fee – $15.00 per session (includes canning book and lunch).

Participants will learn the essentials to home canning such as – equipment, correct canning techniques for low and high acid foods, how to use a pressure canner and water bath canner, answers to frequently asked canning questions about canning vegetables, pickling, and jams/jellies. This class is for anyone who:

  • Uses old canning recipes – such as grandma’s recipes, church cookbooks, etc.
  • Is new to canning or has been doing it for a very long time.
  • Uses recipes that are not Extension-approved.
  • Uses water bath canning for green beans, corn and other low-acid vegetables – this is not a safe practice.
  • Has been canning for a long time without contacting the local Cooperative Extension office for annual updated canning guidelines.

There are two safe ways of canning, depending on the type of food being canned.  These are the boiling water canner method and the pressure canner method.  The boiling water bath method is safe for fruits, tomatoes and pickles, as well as jam, jellies and other preserves.  Pressure canning is the only safe method of canning vegetables, meats, poultry and seafood. 

Food safety is critical to successful home canning.  Although this is not the entire list of guidelines, here are some of the most important food safety rules to follow for home canning:

  1. Don’t make up your own canning recipe.  Without scientific testing, you do not know how much time is needed to process the product safely.  You cannot adjust canning recipes in the same way that you freely change general recipes.
  2. Don’t add extra starch, flour, or other thickener to your recipe.  This will change the rate of heat penetration into the product and can result in under-processing.  The product may be unsafe to eat.  If foods need to be thickened, thicken them after you have opened your canned food and are using it in your favorite recipe.
  3. Don’t add extra onions, chili, bell peppers, or other vegetables to salsa.  The extra vegetables dilute the acidity and can result in botulism poisoning, because the product will not be properly acidified.  It is important to use on Extension-based salsa recipes for home canning. 
  4. Don’t reuse canning lids.  Canning rings can be reused if they are in good condition and have no signs of rust.
  5. Don’t fail to acidify canned tomatoes.  Not all tomatoes have an adequate acid level, especially if the vine is dead.  Not acidifying the tomatoes will result in a product that could support the growth of C. botulinum, a deadly microorganism associated with improperly home-canned foods.
  6. Don’t use your oven instead of a boiling water bath to process high-acid foods.  The product will be under-processed because air is not as good of a heat conductor as water or steam. Also, the jars can explode.

Important Do’s of Home Canning:

  • Have your dial-gauge pressure canner tested each year by contacting your local Extension office.  If the gauge is inaccurate, the food may be under-processed and so the product may be unsafe to eat.
  • Always follow a research-based recipe exactly as instructed.
  • Use only jars designed for canning.  Do not use non-canning jars such as mayonnaise or pickle jars.  These jars can explode, especially if used in a pressure canner, and it might be more difficult to obtain a good seal. 
  • Always use at least 5 percent acetic vinegar when pickling so that low acid vegetables such as cucumbers are properly acidified.
  • Vent the pressure cooker before processing.  The lack of venting can result in air pockets that will not reach as high of a temperature as needed to properly process low-acid foods.

When done properly, home-canning can be a fun and rewarding way of enjoying the taste of summer’s harvest.  Always check with your local Extension office for up-to-date information on the best canning practices.  Linda Minges is a registered dietitian with the NC Cooperative Extension (gaston.ces.ncsu.edu) and can be reached for more information on canning and other food safety topics at 704.922.2127 or linda_minges@ncsu.edu.

Written By

Photo of Susan BuggSusan BuggCounty Extension Support Specialist (704) 922-2110 susan_bugg@ncsu.eduGaston County, North Carolina
Updated on Apr 8, 2013
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