We are often asked how to safely home can a food or special recipe that someone wants to turn into gifts. The other side of the issue is how to tell if the canned food gift you have been given is safe to eat. While it is not possible to guarantee safety with anyone's homemade food items, there are some pointers to keep in mind as you look at that gift and decide how – or even if – to enjoy it. The following tips are offered to help you with some first-line decision making. After that, you will still need to know that the person carried out even recommended procedures correctly. A recipe alone does not tell you that all steps for were followed in carrying out the processing and those can have a great effect on safety, not just the ingredients and food preparation methods.
It is best to make sure the person canning foods at home uses recipes – and procedures -- from sources that can be trusted to know the science behind canning. These are sources that also know what kind of testing should have taken place to develop a canning recommendation in the case of some recipes. Tested or scientifically evaluated processes can be found in the USDA Complete Guide to Home Canning (2009 is the latest version) or the University of Georgia's So Easy to Preserve book (the current version is the 5th edition), the National Center for Home Food Preservation web site, or books from major equipment and ingredient manufacturers, for examples.
It may not be easy to ask questions of your gift-giver. But important things to think about include: where the recipe and canning instructions came from, when it was canned, and how it was made. If the food looks suspicious, it would be better to toss it out than risk getting sick. Pieces of food should be covered with liquid with no discoloration or drying out at the top of the jar. In addition, there should not be unnatural discoloration in the food throughout the jar. Throw out anything with mold growing on it. Before opening the jar, look for signs of spoilage such as cloudy and/or bubbling liquid. Make sure the jar has a vacuum seal when you receive the jar, and again when you open the jar. When you open the jar, make sure there is not spurting of liquid indicating a lot of pressure inside the jar forcing it out. Also notice if there are unusual odors coming from the food in the jar.
However, there can be botulism toxin in sealed jars of low-acid foods without any visible signs or off-odors. It is critical to know how those foods were processed and to trust the giver.
We are not trying to take the fun out of the holidays or the creative side of gift-giving. But we want people to be safe. More about observing home canned foods for spoilage and storing them can be found here: http://www.uga.edu/nchfp/how/store/store_home_canned.html
Enjoy your holidays and start a conversation with your friends about their home canning if necessary!
Elizabeth L. Andress, Ph. D., National Center for Home Food Preservation, December 2010.