Eu decidi tentar enviar minha pergunta por e-mail para o autor, Peter Reinhart. Como se constata, há um erro de digitação no livro!
"Together, the flour and cornmeal should equal 100%. It's the flour % that's listed wrong, not the cornmeal, because the total is 14 oz and the flour is listed as 8 oz. If you divide 8 by 14 you get 57.1%, which means the cornmeal is correctly listed at 42.9% So change the flour percent -- that's a typo I can see can easily happen since 1 and 7 are kind of similar looking and easily overlooked."