If you like to can food out of your garden during the late summer and fall during the harvest season, you might be a little concerned about how best to keep mold and other microorganisms from contaminating your food.
There are a number of different things that you can do to keep mold from growing in your newly canned food, but some of them might not be as obvious as you might think.
For example, paraffin was commonly used years ago to seal the tops of jars for jellies, jams, or preserves. This is no longer recommended, because mold is a common contaminant of these and it can send threads down through the paraffin and end up producing mycotoxins in the food. These soft spreads should be canned as you would anything else.
Food should also be stored properly and at temperatures under about 90 degrees Fahrenheit. Organisms such as mold and bacteria can grow in higher temperatures and foods canned at home that are exposed to high temperatures can get quite hot inside and the air in the top of the jar will expand and break open the seal.
The mold or bacteria will get inside the food and bam -- a jar is wasted. All canned foods should be dated and used within one year.
Before you put any food into your jars, they should be thoroughly sterilized first. This is done by filling the jars and the canner up to about 1 inch over the top of the jars with hot water.
These should then be boiled for around 10 minutes and for every 1,000 feet over 1,000 feet in altitude, add an extra minute. Remove the jars from the water and drain their contents back into the canner to use for processing the foods, since this water is already sterile.
Put the food into the jars, add the lids, and tighten on the screw bands. Some foods are said not to need pre-sterilized jars, but it is better to be safe than sorry, right?
Any food you are going to can should be of good quality, peeled, and thoroughly washed beforehand. Attempting to can any food that is questionable will only result in wasted time and effort.
Food should also not be packed tightly in the jars. Allow some air space between the food and the jar's lid.
Jars must also not be left in the canner after they are finished processing. As the jars cool off, they can suck in water from the pot and this may contain any number of different spores or microbes.
Allow the jars to cool naturally somewhere at room temperature where they will not be bothered.