What do I put into an emergency travel kit?

The kind of food you should bring is canned vegetables and fruits, so mostly canned food. === === The above is great for a kit you don't have to carry it. The canned foods contain water, thus killing two bird with one stone. But they're heavy. So -- if you need to be mobile..: You want to carry the most calories at the least weight. Fats meet this bill but they're REALLY messy, and can thus infect easily. This leaves us at carbohydrates. For serious weight-to-calorie effectiveness, there are compressed sugar bars that are sugar, flavoring (mint is popular), and glycerine (so they don't freeze solid in super-cold temperatures). These were popular on Everest climbs -- they're a heavy calorie boost, and are easy to preserve. For longer treks, consider salt or potassium and a vitamin supplement. Lastly, you say food, but I do need to mention water. Humans can survive a surprising amount of time with no food (80 days for one prisoner in Ireland on a hunger strike!), but no water is a deadly emergency. Have water supplies and purification tablets as well, in case all else fails.