As it turns out, there is no secret process of industrial machinery and mysterious chemicals in between soymilk and tofu. Unlike the process that transforms milk into yogurt, soymilk doesn’t need heat or probiotics to turn it into tofu. The sole ingredient is tofu coagulant.

Tofu coagulants are stirred into soymilk to coagulate, or solidify it, into tofu. They work by interacting with the proteins and solids in the soymilk to separate them out from the liquids into curds that can be pressed into solid tofu. The traditional and most commonly used coagulants are salts. These include:

• Nigari: Similar to sea salt, nigari consists mainly of magnesium chloride from precipitated seawater or brine.
• Gypsum: Gypsum is a mineral made of calcium sulfate, and is harvested from geological deposits.
• Epsom salts: Epsom salt is another name for magnesium sulfate, and are also commonly harvested from natural deposits. It is known for its household and medical uses.

Andrea Nguyen from Viet World Kitchen recommends nigari and gypsum over Epsom salts. While Epsom salts, lemon juice, and vinegar will coagulate soymilk, the taste of the resulting tofu is inferior. Epsom salts are often described as creating a nail polish remover or battery fluid taste. Lemon and vinegar make for lemony and vinegary tofu.

In Ms. Nguyen’s Tofu Coagulant Guide, she writes that she sticks to Sanlinx nigari and gypsum, and describes experiences with unreliable coagulants from both Asian and American markets. She recommends our gypsum and nigari for reliable tofu-making.

We also ship a hefty 8 oz of our own preferred coagulant, Himalayan nigari, with all of our tofu kits.

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Ms. Nguyen is an author, teacher, and consultant. She has appeared on NPR’s Splendid Table, written for Wall Street Journal and Bon Appetit, and taught at the Institute for Culinary Education in New York, to name a few. She blogs at Viet World Kitchen.