To preserve the food and taste of food preservatives are added.
These preservatives are useually Oraganic acids such as acetic acid and benzoic acids ot their salts.
If the food beverages are canned in iron or in any other corrosive mean reactive metal, these acids will react with cans. It will corrode the cans and will destroy the food and beverages and may form toxic substances by reacting with iron or other reactive metals.
To deal with these problems food and beverages industries use tin plated steel cabs tin plating is non poisonous and prevents corrosion.it also preserve the tast of food and beverages by preventing the reaction with cans.