Food items are packed in metal cans to preserve its content for a longer period while doing the same we generally come across food cans manufactured with tin coating and not zinc, this is due to a specific scientific reason that is REACTIVITY. We all are aware of the electrochemical series which determines the reactivity sequence of metals where Zinc is in the seventh position clearly depicting its high reactivity. Thus it can react with slightest acid and make the edible content of the can poisonous, instead of preserving the food it will cause further degradation due to chemical reactions caused by the highly reactive zinc. Whereas on the other hand we have Tin which as compared to zinc lies behind in the reactivity series of the metals and is less reactive thus will not be reacting with the edible content and will even keep it fresh and hygienic without causing any kind of chemical reaction. REACTIVITY is the primary reason for using tin coated cans for storing food and not zinc coated ones.
A secondary reason supporting the previous fact is that Tin has a greater boiling point that is 2,602 °C whereas Zinc has a mere boiling point of 907°C.
Due to the above mentioned factor tin being a much costlier metal than zinc is used to coating food can otherwise the primary objective of preserving the food item will not be solved and we all shall be consuming harmful poisonous substances in the name of canned food.