Canned fish

In the past it was common for many cans to have a key that would be turned to peel the lid of the tin off; most predominately sardines, among others.

From a public safety point of view, foods with low acidity (pH greater than 4.6) need sterilization at high temperatures of 116–130 °C (241–266 °F).

[4] During the first years of the Napoleonic Wars, the French government offered a 12,000 franc prize to anyone who could devise a cheap and effective method of preserving large amounts of food.

Shortly after, the British inventor and merchant Peter Durand patented his own method, this time in a tin can, creating the modern-day process of canning foods.

It became established on the Pacific coast of North America during the nineteenth century, and subsequently expanded to other parts of the world that had easy access to salmon.

[7][8] Shortly after, the Northwest Fur Company started marketing salted salmon from the Columbia River.

It then merged with the Hudson's Bay Company, and the salmon was marketed in Australia, China, Hawaii, Japan and the eastern United States.

They are then packed in either olive, sunflower or soybean oil, water, or in a tomato, chili, or mustard sauce.

[14] Tunas are often caught far from where they are processed for canning, so poor interim conservation can lead to spoilage.

Tuna is typically gutted by hand and later precooked for prescribed times of 45 minutes to three hours.

[15] The retort cooking process kills any bacteria but retains the histamine that can produce rancid flavors.

An Australian study of 53 varieties of unflavored canned tuna found none to exceed the safe histamine level, although some had "off" flavors.

In the United States, the Food and Drug Administration (FDA) regulates the amount of tuna in a can.

[20] In the United States, 52% of canned tuna is used for sandwiches, 22% for salads, and 15% for casseroles and dried, packaged meal mixes.