Dishwasher Jam? Don't do it!

Jam from farmers market
Photo credit: Tiffany Woods

My daughter told me she and her girl friends made strawberry jam they processed in a dishwasher rather than in a boiling water bath. Sounds dangerous to me. What is your opinion? Thank you.

- Clackamas County, OR

OSU Extension does not recommend using a dishwasher for processing jam. Jars processed in dry heat can explode and send broken glass covered with jam all over the place! Additionally, the heat penetration will be uneven and insufficient. These jars need to be brought up to boiling water temperature, 212 degrees F at sea level. Most dishwashers don't get above 165 degrees F.

For jams, a boiling water bath canner should be used. Jams need to be fully submerged in water during processing to expel the oxygen that could help produce mold if left unprocessed.

To prevent spoilage from mold in the jam that they made, the girls can store the jam in the refrigerator for use in the near future or freeze it. If they choose to freeze the jam, be sure to open it and increase the head space by about 1/2" before it goes in the freezer. This way, the jar doesn't break from the expanding jam. The jar lids should be a little loose so air can get out while it is freezing. Tighten the jar lids after the jam has frozen.

Home canners living on a budget can make their own water bath canners from:

  • An existing tall cooking pot. It needs to be able to hold water that will measure 1 to 2 inches above the tallest jar while the water is boiling.
  • A metal tray that elevates the jars off of the bottom of the pot for good water circulation and heat penetration. The metal tray could be from the bottom of a pressure canner (these are sold separately at stores that sell canning supplies or on-line), possibly a round cake cooling rack, the rack from a pressure cooker, or make a trivet of canning jar rings held together with twist-y ties.
  • A tight-fitting lid

There is no substitute equipment for a pressure canner.

Visit OSU Extension food presentation resources page for more information about food preservation and the latest research on preparing food safely.

Glenda Hyde
Family and Community Health Faculty
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