National Nutrient Database for Standard Reference
Nutrient data for 16126, Tofu, firm, prepared with calcium sulfate and magnesium chloride (nigari)
Modifying household measures
b Manufacturers use either magnesium chloride (nigari), calcium sulfate, or both in varying quantities to precipitate the protein. Calcium and magnesium contents will vary accordingly.
a Descriptive terms (soft, firm, extra firm) vary in usage between manufacturers as there are no standards for the various types of tofu.