I don't know how long you travel for, but I regularly travel for work in 1-2 day stretches (so, not too long).

Since I have had an eating disorder for over seven years now, I have a really bad "disaster" mentality around food--meaning, I typically don't travel anywhere without enough food to hold me over in case I can't purchase anything at my destination.

For a single 1-2 day trip, I'll bring things like:

• A couple apples
• A banana (not usually more than one because it gets easily smushed)
• A couple single-serve packets of peanut butter
• Dried fruit
• Nuts
• 3 different varieties of granola bars and protein bars
• A Pro-Bar Meal in case of serious emergency (the brand Pro-Bar makes a 400-calorie-bomb of a nutrition bar, which I always carry on me--came in handy on my flight back from Dublin when they didn't have any more vegetarians option for dinner)
• 2-4 slices of bread (in a hard container to prevent crushing) or a couple english muffins -- easy to pair with the peanut butter and/or banana
• Dry oatmeal -- easy to hijack the coffee maker for hot water, then add the dried fruit + nuts, or the banana and PB
• Pretzels
• Coconut oil in a small container -- use it like a non-perishable version of butter, can be added to bread, etc.
• Animal crackers -- my coworkers make fun of me for this lol; I always have my bag of animal crackers when we travel

I hope those might give you some ideas!

One small note--airport are starting to make you take out all your food when you go through security, like they do with liquids (soooo annoying, since I usually use the food as "fillers" in my suitcase to fit around all my clothes and stuff). Also TSA sometimes considers peanut butter a liquid, so I only use the small <3oz containers and keep them with my liquids just to be safe.