PURPOSE: To feed a coagulant for a bean curd constantly in a given accurate amount even after a storage for a long term, by homogenizing a lactone coagulant for a bean curd with a liquid alcohol to remove moisture and air, and mixing the homogenate with a creaming agent.

CONSTITUTION: A lactone coagulant for a bean curd, e.g. glucono delta lactone is suspended in a liquid alcohol, e.g. glycerol or propylene glycol, and homogenized in a homogenizer, and heated in vacuo to remove moisture and air. A suitable amount of a creaming agent, e.g. sucrose ester of a fatty acid, is mixed, kneaded throughly and homogenized with the homogenate to give the objective coagulant. A new lactone deteriorated by the lactone exchange to some extent is dissociated in an aqueous solution to return to the original acid and alcohol at a different ratio depending on the temperature and time. A bean curd can be prepared smoothly by adjusting the ratio of lactone exchange even on addition to a high-temperature soybean milk without interfering with the preparation of a bean curd packed in a bag due to the rapid coagulation.