Canning novelty. Early methods of manufacture employed poisonous lead solder for sealing the cans. 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. Later studies found this to be false. Increasing mechanization of the canning process, coupled with a huge increase in urban populations across Europe, resulted in a rising demand for canned food. A number of inventions and improvements followed, and by the 1860s smaller machine-made steel cans were possible, and the time to cook food in sealed cans had
Convenience food were used by travelers. Cornmeal that was ground and dried, referred to as "pinolli", was used by travelers as a convenience food in this manner. Canned food was developed in the 19th century, primarily for military use, and became more popular during World War I. The expansion of canning depended significantly upon the development of a machine for producing large quantities of cans very cheaply. Before the 1850s, making a can for food required a skilled tinsmith; afterwards, an unskilled laborer, operating a can-making machine, could produce 15 times as many cans each day. One of the earliest industrial-scale processed