NDSU Extension - Sargent County


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One Way or the Other

One Way or the Other

Canning, freezing, and drying are popular ways to preserve food.  NDSU Extension has many resources and recipes to help you preserve food safely by any of those methods.  The online resources and recipes are available at: www.ag.ndsu.edu/food.

When it comes to canning, there are two options:  hot water bath canning and pressure canning.  Knowing what food is being canned will determine which of those two methods is safe and appropriate. Remember that the scientific basis for safe food preservation rests in chemistry. 

Water-bath canning is appropriate and recommended for naturally acidic or acidified foods – those that have a pH level of 4.6 or lower.  (The lower the pH, the higher the level of acid.) 

High acid foods on the list as safe to be canned in a hot water bath canner, provided science-based preparation steps and processing times are followed, are:

  • Fruits
  • Pickles
  • Sauerkraut
  • Jams
  • Jellies
  • Marmalades
  • Fruit butters/spreads

Pressure canning is recommended for low-acid foods that have a pH above 4.6.  The higher the pH, the more basic (less acid) the food.  Low acid foods are not acidic enough to prevent the growth of bacteria and therefore need to be processed at temperatures of 240 to 250 degrees for a long enough time.  Those essential high temperatures are not possible when using a water bath canner, but they are attainable when using a pressure canner.  Science-based instructions for preparation and processing times for the particular food and specific jar size should also be followed.

Foods to be processed in a pressure canner include:

  • All vegetables except acidified tomatoes
  • Red meats
  • Seafood
  • Poultry

When it comes to canning tomatoes, remember that tomatoes are somewhat of a special case. 

Tomatoes vary in their pH level. For that reason, tomatoes can be safely processed in a water-bath canner only IF they are acidified with lemon juice or citric acid.

To acidify whole, crushed or juiced tomatoes, add 2 tablespoons of bottled lemon juice or ½ teaspoon of citric acid per quart of tomatoes. Use 1 tablespoon of bottled lemon juice or ¼ teaspoon of citric acid for pints. The processing times vary with the food and jar size. 

What about salsas?  Because salsas are mixtures of tomatoes (variable pH) and low acid ingredients, use a science-based salsa recipe that includes adequate acidification prior to canning in a hot water bath canner.  Also be sure to carefully follow the recipe by accurately weighing and measuring all ingredients so as to maintain the proportions.  If you choose to not follow a science-based salsa recipe, it will be safer to freeze it rather than can it. 

If you have questions about preserving foods safely, please call me at 701-724-3355.

Photo Source: https://pixabay.com/photos/green-beans-canning-canned-food-631157/ (downloaded 08/18/20)

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