Why are aluminum and tin containers safe for long term storage of beverages and other food items?
In: Chemistry
Cans usually have a layer of clear lacquer or else paint on the inside, depending on the content. Aluminum is not very resistant to food and drink acids, necessitating the lacquer coating.
Steel corrugated food cans may be plated with tin which is traditional, or with an alloy of zinc and aluminum which is significantly cheaper than tin. Tin-zinc plating have also been used. Tin is much more resistant to food acids, but not wholly so, so a lining of paint tends to be standard. Basic foods like condensed milk or certain vegetables may fare fine in uncoated cans.
The practice of coating the inside of cans is the reason why zinc-based coating has become a more popular option.
*Tin* cans aren’t tin anymore they’re aluminium. Aluminium reacts with the air and forms aluminium oxide which is very unreactive.
They have protective coatings on the inside that prevent corrosion and leaching. These coatings are tailored to suit the content a particular can holds as there is no one-size-fits-all.
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