Why not consider just dropping all processed foods for now. You don't know that rice and beans are a problem for you. Many of us can't eat a lot of processed foods. I get some cookies once in a blue moon but I try to keep it all one ingredient food choices. This is much easier to do than cutting out items that you don't know if you have a problem with or not. It is also much healthier. Do this for a good 2 months and see how you do. You can address a possible additional intolerance at that point if your still having problems. I know others may say to limit everything now and add back in but the corn in processed food seems to be your problem.