Duck blood is the blood of fresh ducks added to the appropriate amount of salt, water to make it coagulate on OK! After coagulation, the duck blood is tender and dissolves the residue, and it can be eaten after boiling in a pot for 5-6 minutes. Generally speaking, for animal blood, once exposed to air, thromboplastin activates rapidly and forms a clot, which is how duck blood forms. If you want duck blood to coagulate and not change back to its original liquid, that's fine too, heat it up! Because the blood coagulation is because of protein denaturation, and over a certain temperature of protein denaturation is not reducible, so you just heat to the blood protein inactivation and denaturation, and after that, no matter what temperature it will not change back to liquid.