Canning is not rocket science, but it is a science nonetheless. Most of all, it is a process; one that requires proper tools and preparation.
We live in a world that is much different from when we first began using this process for food preservation. Back then, you were lucky if the ladle was washed between meals at the tavern where travelers stopped for what was often their only meal of the day.
Today, we are cautious about germs. We are also more cautious about our impact on the environment. Pushing old household items over the bank is not a normal occurrence anymore. We recycle and reuse.
As with other things, we also get carried away in our efforts to adopt earth-friendly behaviors. For instance, there are many ways to recycle glass containers we have acquired at the grocery store, such as pickle jars, but giving them a new life as canning jars is not the way to go.
Commercial establishments where jars are filled with pickles and relish and such use a process that allows for less resistant jars, presumably to lower cost for the consumer. Granny will research this for you, but take my word for now. Such containers as pickle jars are not made with heavy glass and they are not heat-treated.
Let me pause a moment to illustrate my point. Granny makes food for her cat, Marley, and stores it in pickle jars. This, incidentally, is an appropriate way to reuse the jars because Granny is merely storing the food, not canning it, but I learned a valuable lesson when I first began doing this. I placed the hot food in jars and promptly stored them in the refrigerator. When I reached in to lift one out, the bottom stayed in the fridge. The explanation was obvious and we had a good laugh, but Granny since allows the mixture to cool before placing the lids on Lady Alice’s homemade food.
So back to canning. The jar is not the only thing to consider, however. Have you ever wondered why there are more boxes of jar lids than boxes of canning jars on store shelves? You’d think an absent-minded store clerk has made a mistake while ordering and now their poor boss is stuck with all those lids. Not so.
A proper canning lid is designed to form a tight seal on the mouth of its jar. In the course of the canning process, the lid gasket softens and covers the sealing surface of the mouth, yet it allows air to escape from the jar. This is much like suction, allowing the gasket to form an airtight seal when the jar cools. Once a gasket has been heated and cooled, it looses some of its sealing properties.
Without a proper seal, the painstakingly prepared and canned delight in the jar turns into an inviting playground for bacteria. For this reason, lids are used only once. However, the screw band that secures the lid into place may be reused as long as it is not damaged.
“But Granny”, you might ask, “How do I break the seal without damaging the ring when I am trying to open the jar the first time? Doesn’t everybody tap around the lid with the handle of a knife?”
Tut, tut, tut! Even Napoleon knew that a knife is for buttering, not for prying jars open. Use a gripping tool or hold the jar upside down (make sure it is not moist so it does not slip out of your hand) and tap the bottom with the palm of your hand. You will hear a “pop” sound when the seal is released.
So, to recap (no pun intended), recycling fruit spread, mayonnaise or pickle jars for canning may sound practical, but it greatly diminishes the effectiveness of the preserving process and increases the risk of spoilage and of ingesting of less than friendly bacteria. Basically, commercial jars may not withstand the lengthy exposure to high temperatures that is required in the canning process.
There is a lot to be aware of when doing your own canning, but it is simply a matter of obtaining the right information and taking the proper steps. It is well worth your efforts to do some research ahead of time so you can feel certain that the beautiful and colorfully filled jars you place on the table for family and friends contain edible delights that are both safe and nutritious.