My friend Bee Yinn Low posted a recipe on how to make sweet tofu pudding on her site, RasaMalaysia.com. She asked me to give tips on doing it well because she had a little trouble with her sweet doufu hua recipe. Among the comments that Bee received were ones about what to use for coagulating soy milk to produce tofu. People were very confused and I fielded their questions. Obviously, they didn’t have my book but more importantly, clarification is needed. So here we are.
To make tofu you need 3 ingredients: soybeans, water and coagulant. What are your coagulant options and how to choose and get them? I hope to answer your questions here.
What does a coagulant do to soy milk? It solidifies the protein and oil in hot soy milk.
Can you use agar agar or gelatin to coagulate soy milk? No, unless you want to produce soy milk gelatin. “Almond tofu” is gelled with agar agar or unflavored gelatin but it’s more of a jelly than a tofu. The term tofu is often used in China and Japan to denote many jelled things. Tofu is really a different animal. It’s not thickened with a starch or gelatin type of ingredient.
What can be used to coagulate soy milk for tofu: Many things, from everyday vinegar, lemon juice, and recycled/fermented whey to gypsum (calcium sulphate), Epsom salts (magnesium sulfate), nigari (magnesium chloride), and glucono deltalactone (GDL).
Do Japanese tofu makers exclusively use nigari while Chinese tofu makers favor gypsum? No. I asked tofu makers in Taiwan, Japan, and China and it just depends on what they and their customers like. Look on tofu labels and you’ll see that some tofu is made with a combination of coagulants to get at the desired texture. GDL, for example, is added for a more jelly-like finish. There are ethnic divides (e.g., hardcore traditional Viet tofu shops such as Dong Phuong, portrayed in Asian Tofu, use recycled whey) but they are also blurred.
What tofu coagulant is easy for home cooks to use? Gypsum and nigari are the best (and equally good), with Epsom salts coming in third. An acid such as lemon juice or vinegar produces grainy tofu that’s slightly sour tasting. Go with a type of salt!
If you can have only one tofu coagulant, which should it be? As suggested in Asian Tofu, gypsum is the most versatile soy milk coagulant. It produces tofu that’s a little on the sweet side whereas nigari tend to be a touch bitter. The curds are a bit loftier with gypsum so you can coax soy milk into tender tofu. Nigari coagulates quicker but the curds can be smaller than those made with gypsum so your tofu is firmer.
Epsom salts yield slightly grainy results with flavor similar to that of gypsum. If you have room for two (2) tofu coagulants in your life, get gypsum and nigari. If you're in a desperate pinch, run to a drugstore for Epson salts.
How do I find gypsum, nigari or Epsom salts? Use food-grade gypsum (not the stuff in drywall!) to make tofu. It’s used by some brewers and winemakers to tweak pH. If you have a local home brewing supply shop, call and ask for gypsum. Food-grade gypsum can also be purchased online.
Nigari comes as a clear liquid in small bottles, as crystalline or granulated nigari that resembles wet sand, and as dry fine crystals. At Japanese markets, you’ll likely find nigari in small bottles that have little (okay, no) English. In Asian Tofu, we included a photo of the bottle (above) to help cooks find the right kind. Macrobiotic stores or sections in a health food store may have nigari too.
Epsom salts is widely sold in the United States at pharmacies and drugstores. Yes, it’s a laxative and muscle soother but it also works for tofu.
I buy my gypsum and refined from Soymilkmaker.com, where I also buy cheap plastic tofu molds too. The caveat is that you have to buy a lot of coagulant. On the other hand, it only costs $10 for each type. Share it with friends or gift a DIY tofu newbie.
What do I keep around? The stuff I mostly use is gypsum and refined nigari. It’s handy and I can travel with it without TSA searching my carry-on.
Any brands of coagulants to avoid? I had trouble with these:
The gypsum in the small plastic bag came from a Chinese market. I opened it up and it released a strange perfume. I didn’t want that smell in my tofu and that made me suspect. If you have a Chinese brand that you like, use it. My preference is to get it from a reliable source. After taking time to make soy milk from scratch, why take chances on the coagulant?
For some weird reason, the liquid nigari in the orange capped bottle produced very yucky tofu. One of the testers bought it and his soy milk didn’t coagulate quite right. I had the same experience when I used it. The bottle was stocked at Marukai. At other Japanese markets, I’ve mostly found smaller bottles with the white and blue label.
The last is very fine, dry nigari from Ohsawa, a producer of Macrobiotic ingredients. I got it at the Venice, CA, Whole Foods and the curds were finer than those made with chunkier grain, wetter nigari. I may be wrong as Amazon reviews of the Ohsawa nigari have successfully used it for tofu.
How to store tofu coagulants? I store my tofu coagulants in plastic tubs at room temperature. The liquid nigari bottles are kept at room temperature too, though they will form salt crystals if kept too long. The liquid still worked for making tofu.
Got any insights or questions about tofu making? Let me know...
Related post: Is tofu healthy or harmul? (for those who question eating soy)