Find a brand of canned tomatoes that has the inside of the can coated. Those shouldn’t pick up the metallic taste as much.
Tuna is a very high priced item. There are only 2.5 oz of meat inside a small can.
Good points. However, my interest was in how long I could store the canned tomato sauce we normally eat, which is cheap but good. We eat tomato recipes a lot, and it's nice to know the real shelf life. I can store a year's supply on our normal diet and just rotate through - eat the oldest month and replace it. Since the brand we eat lasts longer than a year, it's not worth paying for a more expensive brand if all I want is a single year's supply, or even up to two years.
My approach works if we have a one-year emergency, more or less, but it falls short if we have a longer crisis that starts with several years of Venezuela-style shortages. I've been planning for a crisis that would not go on forever. My preparations may be based on a bad plan if Hillary wins, given what the far left is creating in our country.
As for tuna, that was just a question of variety for our diet. I buy tuna on sale, and I wanted to know its shelf life, since I already have what seems like an unlimited supply of squirrel meat. Fish is much further from home, but I'm not storing enough tuna for even one year.