Canned Corn | Fresh Corn Kernels in a Pressure Canner

This recipe fills 4 500 ml jars; one 1 L jar may also be used, but no larger jar because no processing time has been tested for it. Wash the jars in hot, soapy water, rinse them, and hold them in hot water until filling; because pressure processing also heats the jars, they do not need to be boiled separately for sterilization. Prepare the lids according to the manufacturer’s instructions; do not reuse lids. Place the rack in the pressure canner, add 5–8 cm of hot water, and keep it warm over low heat.

Choose ears with kernels that are slightly underripe or at fresh-eating maturity. Remove the husks and silks, wash the ears, and blanch them in boiling water for 3 minutes. The USDA average is 1 kg of corn in the husk per 500 ml jar.

Stand each ear upright and use a sharp knife to cut through three-quarters of the kernel depth. Do not scrape the cob, as the scrapings thicken the liquid in the jar and no tested processing time is provided for that consistency.

Measure the kernels with a measuring cup and put them in a pot. Add hot water equal to one-quarter of their volume. Bring to a boil, then cook over low heat for 5 minutes; this is the hot-pack step.

Fill the jars with the corn and its cooking liquid, leaving 2.5 cm of headspace. If desired, add half a 4 ml measure of salt to each 500 ml jar; the salt is for flavor only. Remove air bubbles with a plastic spatula, restore the headspace to 2.5 cm, wipe the rim with a clean, damp cloth, and close the jar.

Place the jars upright on the rack so they do not touch. Lock the canner lid with the vent pipe open and turn the heat to high. Once a steady stream of steam comes from the vent, let it vent for 10 minutes; air left in the canner keeps the temperature low even if the gauge shows the expected pressure. Then attach the weight or close the valve and wait for the pressure to rise.

Choose the pressure according to altitude. With a weighted-gauge canner: 10 psi from 0–305 m and 15 psi above 305 m. With a dial-gauge canner: 11 psi from 0–610 m, 12 psi from 610–1,219 m, 13 psi from 1,219–1,829 m, and 14 psi from 1,829–2,438 m. Istanbul and Izmir are in the first band (10 psi with a weighted gauge, 11 psi with a dial gauge); Ankara is at 938 m (15 psi with a weighted gauge, 12 psi with a dial gauge); the city center of Erzurum is above 1,829 m (15 psi with a weighted gauge, 14 psi with a dial gauge). Have the accuracy of a dial gauge tested every year before use. Start the processing time as soon as the gauge shows the pressure appropriate for your altitude: process corn for 55 minutes in a 500 ml jar and 85 minutes in a 1 L jar. Adjust the heat to maintain steady pressure; if the pressure drops below the target at any point, bring the canner back to pressure and restart the processing time from the beginning.

When the processing time is up, turn off the heat and wait for the pressure to drop naturally to zero without moving the canner. Do not cool the canner with cold water or open the valve early: cooling is part of the tested process, and a sudden pressure drop can cause liquid to escape from the jars. When the gauge reads zero, remove the weight or open the valve, wait 10 minutes, then open the lid away from you so steam does not hit your face.

Use jar lifters to remove the jars while keeping them upright. Place them 2.5 cm apart on a towel or wire rack; leave them undisturbed to cool for 12–24 hours, and do not tighten the lids. Once cool, press the center of each lid with your finger: it is sealed if the center is concave and does not move when pressed. If it springs back or clicks up and down, it is not sealed. Refrigerate an unsealed jar and use it soon, as you would cooked food. Label sealed jars with the product name and date.

Store sealed jars in a cool, dry place away from direct light. Before opening, inspect the lid: the food is spoiled if the lid is bulging, the jar is leaking, liquid spurts or foams when opened, or the contents are moldy or smell bad. Do not taste a questionable jar. If it is unopened, put it in a sturdy bag, tie it tightly, and discard it. Botulinum toxin does not always cause visible signs, so following the time and pressure exactly is the only safeguard.