You can always tell what season it is by the questions we get in the office. Right now folks are still “putting up” (preserving) foods. One of the key questions I received this week is: “Can mayonnaise jars made by a company that makes canning jars be used in home food preservation?” The answer is no!

“Companies making both canning jars and other types of jars caution against using commercial jars for home canning,” said Amelia Mitchell, a regional food safety agent with Alabama Extension that has food safety programs in Escambia and six other counties in our (southwest) Region.

Mitchell offers several reasons for this:

• Metal knives are commonly used to scrape the last bit of peanut butter or mayonnaise from a commercial jar. These may scratch the inside of the jar and leave a weak spot where it could break during canning.

• Commercial jars are lighter weight and contain less glass than home canning jars.

• Commercial jars are sometimes larger than standard home canning jars and, if food is home-canned in these jars according to standard processing time, the food may be under processed and spoil.

• Commercial jars are frequently made for a food product that is packed cold. Therefore, these jars may not withstand the high temperatures used in home canning.

• Commercial jars are made to seal with one-piece caps and may not seal properly with a two-piece home canning cap.

Regular and wide-mouth “Mason” or “Ball” canning jars are the best choice for home canning. Jars are available in 1/2 pint, 1 pint, 1 1/2 pint and quart sizes. Wide-mouth jars have openings of about 3 inches, making them easier to clean, fill and empty. Mitchell says you can sometimes find half gallon jars that can be used to can juices. There are no processing times for this size jar for fruits and vegetables.

With careful use and handling, the “Mason” or “Ball” type canning jars and metal screw band may be reused many times for several years. However, you must use a new metal lid each time. When these jars are processed properly, the jar seals and vacuums are excellent and jar breakage is rare.

“Never use peanut butter and pickle jars for canning any food at home because they cannot be sealed with the two-piece self-sealing lids,” Mitchell said.

For more information on this and other food safety and quality questions, please give Amelia Mitchell, Regional Food Safety Agent, a call at the Mobile County Extension Office at (251) 574-8445.