Unlike foodborne infections that strike without warning, folks who have food allergies (or food intolerance) generally know of them and avoid the offending ingredients.
Wendy’s first line of defense is their quality systems in place at each processing plant and a trained workforce and a system that alerts them to possible presence of foreign materials.
While the senses of sight, touch, hearing and smell are not the only tools used to eliminate contamination, they are not used as often or as thoroughly as possible.