PPO, also known as tyrosinase, polyphenolase, phenoloxidase, phenolase, cresolase, catecholase, and catechol oxidase, has its enzyme activity in the melanosis process inhibited by sulfite‐based compounds and their derivatives in crustaceans, especially shrimp (Sae‐leaw and Benjakul 2019). This evidence concerns the gene PPOX and freckles.