Why are noodles white?

Most noodles start as some kind of dough made primarily from flour. The majority of flour produced in large quantities comes from wheat, rice, and corn. The vast majority of commercially-available noodles are wheat-based. Wheat and rice flour appear white, thus the uncooked noodles made from these flours are white. Once cooked, the starches in the noodles gelatinize and absorb water. This leads to the noodles turning translucent, allowing the colored pigments in the foods or sauces mixed with them to show through.