Combine egg white, grapefruit juice concentrate, and hot sauce in a shallow bowl, stirring well. Set aside. Combine crumbs, cheese, and sesame seeds in a small bowl , stirring well. Dip fillets in egg white mixture, then dredge in crumb mixture. Arrange fillets on a baking dish that has been coated with cooking spray. Drizzle butter evenly over fillets.
Bake at 400°F for 10 minutes or until fish flakes easily when tested with a fork.