Pressure canning is use to preserve foods that are low in acidity. Pressure canning is necesary for low-acid foods because low-acid foods require higher temperatures than the boiling point of water to kill the Clostridium botulinum bacteria that may be find in these types of preserved foods. Foods that are low in acidity has a pH level of 4.6 or higher, and include foods like vegetables, meats, and soups.
Although many people attempt to use water bath canning for preserving low-acid foods, this method is not sufficient for these types of foods because water bath canning do not reach the temperatures required to kill the Clostridium botulinum bacteria. Whereas Clostridium botulinum bacteria can survive in boiling water, the heat and steam within a pressure canner destroys the bacteria. If the Clostridium botulinum bacteria are not destroy during the canning process, the bacteria may produce a toxin that is present within the preserved food.
How to Pressure Can Food Safely
This toxin is odorless, tasteless, yet is more deadly to humans should an individual consume the food containing this toxin. In order to pressure can foods, rules must be followed to ensure the safety of the canned foods. One rule is that you should use only tested recipes in the pressure canner.
Additionally, the individual should adjust the processing times and pressures within the canner according to the altitude at which the individual live. The processing times and pressures must be followed exactly as the incorrect amount of time or pressure may not be able to kill the Clostridium botulinum bacteria. For instance, green beans require specific amount of time to process in both pint and quart sized jars, as well as require specific amount of pressure within the canner according to the altitude of the individual preparing the jarred goods.
The altitude at which an individual lives affects the atmospheric pressure within the Earths atmosphere. The atmospheric pressure affects the boiling point of water and the internal pressure of the pressure canner. For instance, the required pressure within a pressure canner is 10 PSI at sea level.
However, as the altitude increases, the required PSI within the canner increases, as well. For instance, if the individual lives at an altitude of 1,001 to 2,000 feet above sea level, the required PSI is 12. However, if the individual lives at an altitude of 4,000 feet above sea level, the required PSI is 15.
An individual can determine the altitude at which the individual lives with the aid of a map or online tool. Based off the altitude of the individual, a processing chart can determine the required PSI. The time for which the jars should be processed can be determined by laboratory testing of the food to be canned.
Different types of foods require different processing times. For instance, green beans require 20 minutes of processing to be safely preserve in pint sized jars, yet require more processing time if the quantity of green beans is to be processed in quart sized jars instead of pint sized jars. Foods that contain protein, such as beef or chicken, require 75 to 90 minutes of processing time because of the dense nature of these meats.
Additionally, mixed vegetables require the same processing time as the vegetable that takes the longest to cook to ensure that all vegetables are safely preserve. Fish require 100 minutes of processing at 11 PSI, and soups require 60 to 75 minutes of processing. In order to safely use a pressure canner, certain steps must be followed.
First, you must vent the steam from the canner for 10 full minutes to remove air pockets from within the jars. This step must be taken with the intention of ensuring the food is preserved in a setting that reaches the appropriate temperatures. After the steam is vented, the canner is to be brought to the required PSI of the food being canned, and the processing time is to begin.
After the processing time has completed, the canner should cool natural without releasing the pressure from the canner. The lid is only to be removed once the pressure within the canner reaches zero PSI. Certain mistakes should be avoided when pressure canning the foods.
One mistake that should be avoided is attempting to overload the jars with the foods to be canned. Additionally, the correct amount of headspace should be left within each jar. Headspaced ensures the jars properly seal when the jars cool with the foods.
Additionally, one should take care to avoid rushing the venting of the steam from the jars. Additionally, you should avoid recipes that have not been tested by the USDA. After the jars have been cooled for at least 24 hours, the individual should test the seal upon each jar by pressing the lid in the center of each jar.
If the lid flexes, it indicates that the jar has not sealed properly, and the jar should be immediately move to the refrigerator. If the processing times for each type of food are followed, and if the correct PSI settings are followed according to the altitude at which the individual lives, those canned goods can be stored for up to one year. Additionally, the canned vegetables, meats, and soups can contribute to the food security of an individual or family.
Canned foods do not require electricity or refrigeration until they are to be opened and eat. Each jar should be appropriately label with the date of candying of the food, as well as the type of food being preserved in the jar. By following the instructions and steps within this description, the food will remain safe to eat and nutritious for a period of time.