Most foods can go through security, as long as they are not liquids or gels over 3.4oz. However, they can sometimes be subject to additional screening, which may slow you down in line, so keep that in mind. As for when you get on the plane, it’s courteous to avoid common allergens, such as items with nuts, as well as strong smelling foods. Messy items that get crumbs all over are another thing to steer clear of. Good items may include: bite sized cracker, fruit gummies, cut up fruit, and squeezable applesauce.