You mean is it – like James Bond – licensed to kill? Ah, nothing so dramatic. In Italy, flour is classified either as 1, 0, or 00, and refers to how finely ground the flour is and how much of the bran and germ have been removed. Doppio zero is the most highly refined and is talcum-powder soft. Many people assume that this softness also means that the flour is low in protein, and therefore particularly suitable for making pasta but unsuitable for making bread. They are wrong. Wrong, wrong, wrong.
Jeffrey Steingarten cogently explains in his book, It Must’ve Been Something I Ate (Canada, UK), flours of varying protein levels can be milled to the 00 category. He had a number of samples of flour analyzed in a lab and found the 00 flours to be higher in protein than many of the less-refined ones. Higher protein 00 flours that are suitable for making bread are labeled in Italy as “panifiable” – essentially “bread-ready.”
Steingarten says cooks in the United States sometimes substitute a mix of low-protein cake flour and all-purpose flour for the 00 flour called for in a pasta recipe. But Marcella Hazan, author of The Essentials of Classic Italian Cooking (Canada, UK), says she finds that all-purpose flour does the “most consistently satisfying job” in standing in for the doppio zero.