D.S.
I second Sylvia G's input - it sounds like a sensory issue more than a picky eater. As a special ed teacher for kids this age, I see this kind of thing often. I would call child find just to rule it out -an evaluation is free, and a speech therapist or an occupational therapist could probably help you get him over it fairly quickly. Her link is a great one too, please check it out and GL!
Deb