A Prize for Feeding Armies
In the late 1790s the French government, at war and struggling to supply its armies and navy, offered a reward for a practical way to preserve food. Nicolas Appert, a confectioner and food professional working near Paris, spent years experimenting. His method was to fill glass bottles or jars with food, cork them tightly, seal them, and heat them in boiling water for a time. By around 1810 he had been recognized by the authorities, reportedly with a prize, and published a book describing his process.
Appert’s work is the usual starting point for canning, although he did not use cans. The word comes from what the technique became. His products included soups, vegetables, fruit and meat, and he later ran a business producing them.
From Glass to Tin
Glass bottles were breakable, awkward to ship and a poor fit for rough naval or expedition use. In 1810 a patent in Britain, taken out by the merchant Peter Durand, described preserving food in containers of tin-plated iron as well as glass. Soon after, the English engineers and manufacturers Bryan Donkin and John Hall developed a commercial canning operation, and tinned foods were supplied to the Royal Navy, loaded aboard sailing ships and used on polar expeditions.
Early cans were handmade. Workers cut and soldered thick tinplate, and a skilled tinsmith could produce only a limited number each day. Cans were expensive and seen as a specialty for travelers and the military. Mass production, mechanized sealing and better tinplate gradually brought prices down through the nineteenth century, and the American Civil War is often cited as increasing demand for canned goods.
The Long Debate About Why It Worked
Appert had no explanation for his results beyond the observation that heated, sealed food lasted. Early theories ranged widely. Some people attributed spoilage to air itself, and thought sealing out air was the whole trick. Others looked for chemical reasons.
Louis Pasteur’s work in the 1850s and 1860s on fermentation and spoilage supported the view that microorganisms cause food to decay, and that heat could destroy them. This fit within the wider acceptance of germ theory. Even so, the details of canning were hard to nail down. Which kinds of microscopic life survive boiling? How long is enough? Some hardy bacterial spores can survive ordinary boiling, which helps explain why early canned foods sometimes spoiled or failed unpredictably, and why higher-temperature steam processing in closed vessels, a kind of industrial pressure cooker, became standard in industry.
By the late nineteenth century, researchers at universities and in industry were studying heat penetration and bacterial survival more systematically. Their work led to scheduled processes tailored to each food, so that acidic fruit and low-acid vegetables or meat were treated differently. Exact numbers vary by food and container, and this article does not give instructions.
Glass Comes Back to the Kitchen
Glass jars regained popularity for home use. In 1858 John Landis Mason of New York patented a jar with a screw thread to take a metal lid, a design that became a household staple. Later improvements added rubber rings and two-piece lids, and home canning grew into a regular summer task in many households, particularly in North America.
Manufacturers and agricultural extension services then promoted tested methods, in part because home canning mistakes can create dangerous conditions. Guidelines have been revised as knowledge has improved, so historic recipes should not be treated as current instructions.
Why Canning Mattered
Canned food made several things easier. It also helped create the modern habit of buying convenience foods from a shelf.
- Armies, ships and expeditions could carry reliable provisions.
- Seasonal produce and fish could be sold away from where and when they were harvested.
- Cities received a steady supply of year-round food, though quality varied.
- Industrial food companies grew up around canneries, tin production and labeling.
Canning had drawbacks as well. Early tin cans were sometimes made with lead solder, which has been proposed as a hazard on some nineteenth-century voyages, though historians still discuss how much it contributed. Canned foods also differ from fresh ones in texture and taste. In some ways canning was the first rival to what later became refrigerated shipping, since both let food travel far from where it was grown. Even so, the basic principle, heat then seal, remains central to shelf-stable food today, now using pouches, retort cartons and aluminum as well as tin-coated steel.
The tin can also raised a practical question that took a surprisingly long time to answer, which was how a customer was supposed to open it; the can opener did not appear for decades.