What is a Pressure Canner?

A pressure canner is the special piece of equipment you will need for processing low-acid food (i.e. non-pickled vegetables, meat, etc.) safely at home.
  
They operate similarly to a pressure cooker – in that food is heated at a high pressure (thus high temperature) environment.  Instead of cooking the food directly in a pressure cooker, the food is packed into jars then processed at a certain pressure and time period (varies with different food items). This processing mimics commercial canneries, where food is heat treated to remove contaminants, cook food and vacuum seal at the same time.
   
The most common size of a pressure canner is 23 quarts (21.7L), which fits 7 x quart jars in a single layer, or 2 x layers of 9-10 pint jars. Pressure canners can be used for pressure canning, as a large boiling water canner and also for cooking, if desired.
  
Modern pressure canners are MUCH safer than older models – they are lighter and have a safety fuse (to release pressure when it climbs too high). They have 1-2 racks inside, one for the base (to prevent jars bouncing on the base) and a second rack if double stacking jars (to prevent jars bouncing against one another). The major brands are also easy to find replacement parts – such as dial gauges, rubber gaskets (which sit inside the lid), weights, etc.
   
Always refer to your manufacturing booklet to learn how to operate your pressure canner, as models and brands do vary and ALWAYS follow a pressure canning recipe.
   
Fresh produce naturally contains bacteria, if acid is not present then pressure canning is required to prevent botulism. This high temperature (created by the higher pressure level) is what kills these microorganisms. Pressure canners process your low acid food at 240°F (115°C) at sea level, which is why pressure levels (thus the temperature) is changed for different altitudes, as water boils at different temperatures at higher/lower altitudes.
   
BEFORE starting pressure canning, ensure you understand how your canner works (you can run a small practice batch of vegetables or even water in jars the first time) and allow enough time to prepare, heat jars and process them before removing them from the canner.
  

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