Waterbath vs. Pressure Canning

The USDA has identified two methods for canning proven safe for ridding food product of enzymes, molds, yeasts and potentially dangerous bacteria. The type of food you're planning to preserve will determine which canning method will be used, and your recipe will specify that method. Do not deviate if a pressure canner is required.

All foods are canned by one of two methods:
  1. Boiling-Water Bath. Fruits and pickled foods, identified as high-acid products, can be processed or heated using a boiling-water bath. The heat from the boiling water (212 degrees Fahrenheit) is transfrerred to the product as it completely surrounds each jar and lid. These include all fruits, tomatoes, sauerkraut, and most foods to which vinegar has been added, such as most pickles and relishes. This method cannot be used for meats, vegetables, soup, or other low-acid foods. The water temperature never reaches the point to destroy the bacteria known to cause salmonella, staphylococcus, and botulism.

  2. Pressure Canner Method. Used for foods containing little acid. These include vegetables, except for tomatoes, and meats, seafood, and mixes of food that include some low-acid foods. The pressure canner superheats to a temperature of 240 degrees Fahrenheit. Because the steam inside the canner is pressurized, it reaches a temperature that exceeds that of boiling water. The heat is sufficient to kill all food contaminants, including dangerous bacteria. Use a pressure canner for low acid foods such as vegetables, meats, mushrooms, and soups. Unless pickled, the pressure canning method should also be used with any combination fo high and low-acid foods.