Canning salsa entails subjecting it to high temperatures for an extended period of time for the purpose of preservation. Although most foods require a pressure canner to meet the conditions needed to eliminate harmful bacteria, the high-acid content of salsa effectively protects it from pathogens that cause food-borne illness, and permits it to be canned safely at a lower temperature. These characteristics make salsa, as well as other acidic foods, ideal for the open-kettle method of canning – processing jarred food in a 180 degree Fahrenheit hot-water bath.
Wash the pint jars and lids and scald them in boiling water for 10 minutes. Alternatively, wash them in a dishwasher with a sanitizing function. Allow the jars and lids to air dry.
Fill the canning jars with the salsa, leaving 1/2 inch of head space. Wipe any salsa from the jars' exteriors. Place the lids on the canning jars and secure with the screw band.
Place a 12-inch by 17-inch wire cooling rack in the bottom of a 32-qt. stockpot. Fill the stockpot half full of water. Place the jars on the wire rack. The jars should be completely submerged.
Bring the water to a simmer over medium-high heat and process for 35 minutes, beginning when the water returns to a simmer. Remove the jars with a lid lifter and place on a wire rack to cool.
Check the lid for a depression indicating the presence of a vacuum. Tap the lid with the bottom of a spoon; a properly sealed jar will produce a clear ring when tapped. Immediately reprocess any jars not properly sealed or use within three days.