Canning

Although appearance, smell, and vitamin content had deteriorated, there was no trace of microbial growth and the 109-year-old food was determined to be still safe to eat.

[3] Shortly before the Napoleonic Wars, the French government offered a hefty cash award of 12,000 francs to any inventor who could devise a cheap and effective method of preserving large amounts of food to create well-preserved military rations for the Grande Armée.

Based on Appert's methods of food preservation, the tin can process was allegedly developed by Frenchman Philippe de Girard, who came to London and used British merchant Peter Durand as an agent to patent his own idea in 1810.

[7] Bryan Donkin developed the process of packaging food in sealed airtight cans, made of tinned wrought iron.

In 1824, Sir William Edward Parry took canned beef and pea soup with him on his voyage to the Arctic in HMS Fury, during his search for a northwestern passage to India.

Studies in the 1980s attributed the lead from the cans as a factor in the disastrous outcome of the 1845 Franklin expedition to chart and navigate the Northwest Passage.

Urban populations in Victorian Britain demanded ever-increasing quantities of cheap, varied, quality food that they could keep at home without having to go shopping daily.

In response, companies such as Underwood, Nestlé, Heinz, and others provided quality canned food for sale to working class city-dwellers.

The late 19th century saw the range of canned food available to urban populations greatly increase, as canners competed with each other using novel foodstuffs, highly decorated printed labels, and lower prices.

After the war, companies that had supplied military canned food began to improve the quality of their goods for civilian sale.

To prevent the food from being spoiled before and during containment, a number of methods are used: pasteurisation, boiling (and other applications of high temperature over a period of time), refrigeration, freezing, drying, vacuum treatment, antimicrobial agents that are natural to the recipe of the foods being preserved, a sufficient dose of ionizing radiation, submersion in a strong saline solution, acid, base, osmotically extreme (for example very sugary) or other microbially-challenging environments.

The spores of the microorganism Clostridium botulinum (which causes botulism) can be eliminated only at temperatures above the boiling point of water.

As a result, from a public safety point of view, foods with low acidity (a pH more than 4.6) need sterilization under high temperature (116–130 °C).

To make a sanitary can and lid suitable for double seaming, manufacture begins with a sheet of coated tin plate.

Precision is required to ensure that the welded sides are perfectly aligned, as any misalignment will cause inconsistent flange shape, compromising its integrity.

The base plate provides a sure footing for the can body during the seaming operation and the chuck fits snugly into the end (lid).

All sanitary cans require a filling medium within the seam because otherwise the metal-to-metal contact will not maintain a hermetic seal.

For example, due to the springback effect, a seam can appear loose, when in reality it was closed too tight and has opened up like a spring.

For this reason, experienced operators and good seamer setup are critical to ensure that double seams are properly closed.

Quality control usually involves taking full cans from the line – one per seamer head, at least once or twice per shift, and performing a teardown operation (wrinkle/tightness), mechanical tests (external thickness, seamer length/height and countersink) as well as cutting the seam open with a twin blade saw and measuring with a double seam inspection system.

[15] The heating process during canning appears to make dietary fiber more soluble, and therefore more readily fermented in the colon into gases and physiologically active byproducts.

Since the refrigerator did not exist and industrial canning standards were not set in place it was very common for contaminated cans to slip onto the grocery store shelves.

[17] According to The Fruits of Empire: Art, Food and the Politics of Race in the Age of American Expansion by Shana Klein, "Workers also suffered injuries, specifically bruised knuckles and open sores, from trimming and packaging pineapples.

[21] Salt (sodium chloride), dissolved in water, is used in the canning process, which helps prevent spoilage and can improve sensory characteristics.

C. botulinum prefers low oxygen environments and is a poor competitor to other bacteria, but its spores are resistant to thermal treatments.

[30] Botulism is a rare but serious paralytic illness, leading to paralysis that typically starts with the muscles of the face and then spreads towards the limbs.

[31] Canned goods and canning supplies sell particularly well in times of recession due to the tendency of financially stressed individuals to engage in cocooning, a term used by retail analysts to describe the phenomenon in which people choose to stay at home instead of adding expenditures to their budget by dining out and socializing outside the home.