Preserving Food by Canning — Appert's Heat-and-Seal Method That Fed Armies

In 1810 a French confectioner named Nicolas Appert won a prize from Napoleon's government for solving a problem that had plagued every army and navy in history: how to keep food from spoiling. His answer was deceptively simple — pack food in a sealed container and heat it thoroughly. Food preserved this way kept for months, even years, and the modern canning industry was born.

Appert did not know why it worked; it would take Louis Pasteur, fifty years later, to show that heat kills the microbes that spoil food and the seal keeps new ones out. But the method worked perfectly without that knowledge. Soon glass jars gave way to soldered tin cans — lighter, unbreakable, and ideal for soldiers and sailors — and canned food spread around the world.

Canning sits alongside salting, drying, and smoking as one of humanity's great preservation methods, but it was the first to keep food fresh-tasting and the first born of the industrial age. One caution it shares with all low-acid preserving: ordinary boiling does not destroy the spores of botulism, so low-acid foods must be acidified or pressure-canned — a lesson learned long after Appert.