You can use either cornmeal or breadcrumbs to add a crust to fillets of fish, chicken or pork, but that’s where their commonalities end. In most recipes, the two items are not interchangeable. Breadcrumbs are — as the name suggests — ground bread used to coat proteins, to bind ground meat dishes, to top casseroles or to make stuffing. Any type of bread can be made into breadcrumbs. Cornmeal, or ground dried corn, has a number of culinary applications, including porridge, polenta, bread and tortillas.
Breadcrumbs made from very dry bread create a crispy coating on fried foods, and cornmeal creates an even crunchier, firmer coating. Your choice depends on your personal taste and the flavor of the recipe, although cornmeal lends itself to Southern- or Latin-inspired flavors. To use either breadcrumbs or cornmeal to create a coating, follow classic breading procedures: Dust the item to be fried in flour, dip it into beaten egg and finish by rolling it gently in the breadcrumbs or cornmeal.
References and ResourcesThe Cook's Thesaurus: Crumbs
What's Cooking America: Baking and Cooking Ingredient Substitution Chart
Family Time: Breading Meat, Fish, and Poultry