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
Cat food paper bags, sometimes with a plastic film layer; similar bag styles with film laminates or coextrusions are also used. Wet cat food is often packed in aluminum cans or steel cans. Packaging regulations for cat food are often very similar to corresponding regulations for human foods. The energy requirements for adult cats range from 60–70 kcal metabolizable energy/kg body weight (BW) per day for inactive cats to 80–90 kcal/kg BW for active cats. Kittens at five weeks of age require 250 kcal/kg BW. The requirement drops with age, to 100 kcal/kg BW at 30 weeks and to the adult requirement