Standard Mason style canning jars have been used for home food preservation for decades. In the last few years, creative people are finding new uses for canning jars as they have become a trendy decorative item. What is safe for food preservation and what is safe to maintain the integrity of your jars?
Vintage or antique canning jars are perfect for decorative use. Canning jars have a life expectancy of 10-13 years. After that, you will experience more breakage because of the wear and tear of normal use. Because of this, it is not recommended to use vintage or antique canning jars for food preservation. Instead, enjoy those jars as vases, canisters, or just a pretty touch of color. In addition, jars with wire bales and rubber rings should be used for storage only, not for food preservation. Before purchasing jars for food preservation, always read the labels carefully so you know the intended use of the jar.
New ‘Ball’ Jars
In 2017, Ball released newly designed jars, including a Spiral Jar, in 16 and 28 ounce sizes, and a Sharing Mason Jar, available in a 16 ounce size. As well as different types of jars, there are many sizes of jars- ranging from 4 ounces to one gallon sizes. Half-gallon jars are only recommended for very acid juices, such as fruit, while one gallon jars are not recommended for food preservation.
Several different colored canning jars are available in stores. Blue, green, and purple jars have been made for home food preservation. However, there are other colored jars, such as yellow, available for craft projects, but are not recommended for food preservation. Read the labels carefully so you know the intended use of the jar.
Reusing Commercial Jars
Most commercial glass pint and quart size mayonnaise or salad dressing jars may be used with new two-piece lids for canning acid foods. However, you should expect more seal failures and jars breakage since these jars have a narrower sealing surface and are tempered less than Mason jars, and may be weakened by repeated contact with metal spoons or knives used in dispensing mayonnaise or salad dressing. It is recommended that these jars only be used for water bath canning for best success.
While jars with on-piece twist top lids are also available to purchase, The National Center for Home Food Preservation still recommends using a two-piece metal home canning lid system for home food preservation. Processing times are researched and determined with standard volume/size and shape of canning jars with a two-piece lid. With a two-piece lid, it is easy to determine if the jar sealed and is shelf-safe. For home canning, always choose the two-piece lid for best results.
Several recipes have been making the circuit that show canning jars used to bake breads and cakes. When the hot bread or cake is removed from the oven, a canning lid is put on the jar. As it cools, a vacuum occurs which seals the lid and it appears to have been “canned”. This is not a safe idea as the low-acid foods have the potential for supporting the growth of bacteria like Clostridium Botulinum if it is present in the jar. These products might be available commercially; however, additives, preservatives, and processing controls not available for home recipes are used. The manufacturers of home canning jars do not endorse baking in their jars. Even if you do not try to seal the jars to “can” the bread or cake, it is not a good idea to use the jars for this method. There is a significant risk for consumers to become injured from broken glass when baking breads or cakes in glass canning jars. Canning jars are intended for use in hot water baths or pressure canners. They are not designed to withstand the thermal stresses that occur with dry oven heat. If someone gives you a home canned bread or cake product, assume that it is unsafe to eat and discard the contents.
To keep jars in good condition, avoid sudden temperature changes. Do not put a hot jar on a cool surface or put raw packed jars into boiling water. Always use a rack in the bottom of the canner to prevent jars from sitting directly on the bottom of the canner. Do not use metal utensils when removing air bubbles from hot jars. A metal knife can scratch the glass and create a weak spot, which could become the point of breakage. Use recommended headspace for food to expand in jars when heated. Do not lower pressure or temperature too quickly when the processing time is completed. With a pressure canner, remove canner from the heat and let stand until pressure is zero. With a boiling water bath canner, take the lid off and allow five minutes of cooling time before removing jars from the water.