The primary concern when canning hot peppers involves sterilization of the lids and jars in which the peppers are preserved. Home-canned foods that are improperly processed run the risk of developing the deadly botulism bacteria. One might assume that hot peppers are safe from bacterial incursion because of the vegetable's spicy nature, but the exact opposite is true. Hot peppers are naturally low in acidic content, and low-acid foods must always be subjected to pressure and heat to ensure safe preservation.
The first step in canning hot peppers involves protecting the hands and eyes. Many peppers, especially the hottest varieties such as habaneros and the Bhut Jolokia pepper from northeast India, can cause severe burns on bare skin. It is best to wear rubber or latex gloves when handling peppers, and it is especially crucial to avoid touching the face or eyes. A substance known as capsaicin causes the heat inherent to most peppers. Direct exposure to peppers with the strongest concentrations of capsaicin typically results in extreme pain, blisters and possibly even blindness.
Hot peppers should be prepared before canning. The most common preparation method for small peppers begins with peeling away the outer skin. Slit the peppers lengthwise, then roast them in a 400-degree Fahrenheit (204-degree Celsius) oven until the skin blisters. Allow the peppers to cool, dip them in ice water, then peel away the skins. Large peppers should be quartered first.
The jars used for canning hot peppers should be sterilized before being filled. Wipe the tops of the jars, the lids and the lid-tightening bands. The sealed jars should be placed on a jar rack in a pressure canner containing 2 inches (5.08 cm) of water. Close the lid of the pressure canner, turn the heat to high, and sterilize the jars per the manufacturer's directions. Tables that provide exact times for sterilizing jars and canning hot peppers in a pressurized cooker are also available on the Internet.
After the jars have been sterilized and cooled, they can be loosely packed with peppers. Pour boiling water into the jars, stopping when the water level is 1 inch (2.54 cm) from the jar's lip. Place the lids on the jars, screw on the lid-tightening bands, and process them in a pressure canner by following the manufacturer's guidelines. Peppers that have been canned in such a manner are safe for consumption for at least one year.