Introduction: Making Your Own Tofu

About: I'm a physics and chemistry teacher at a public school in Maryland and active in my local science teacher's association. I love building things and am teaching myself how to use arduino in electronics projects…
Tofu is probably something you never thought you could make at home, but its actually not that difficult. You just have to use a little bit of kitchen chemistry!

Materials needed:
  • 1 qt. soy milk (or dry soy beans and a soy milk machine)
  • food grade magnesium chloride (calcium sulfate can be substituted)
  • sauce pot
  • large spoon
  • small strainer
  • microwave
  • measuring cup
  • tofu mold
  • cheese cloth

Tofu is a versatile food that can be used to imitate many popular junk foods in a healthy form such as scrambled eggs, buffalo wings (boneless of course!), pudding, and many others. Tofu itself is simply compressed soy milk curds. With a bit of magnesium chloride soy milk transforms into the most delicious tofu you have ever eaten! You can tweak the recipe to make different consistency from light silken tofu to firm. I made firm tofu for this instructable.

The science behind this process is that when hot milk and a magnesium chloride solution are combined, the caseins in the milk separate from the whey proteins. A similar reaction can be completed by adding an acid such as vinegar to cold milk to form curds which can then be pressed into a block of cheese. If milk is left in the refrigerator for too long, it will start to curdle indicating to the user that it is spoiled. This reaction is caused by acid producing bacteria which are causing the same separation as I will show you to produce tofu.

Step 1: Making Soy Milk

I prefer to use freshly made soy milk for my tofu so here are the directions to make the soy milk.

Start with dry soy beans and soak them for six hours to rehydrate. Rinse the beans right before putting them into  the soy milk maker.

Step 2: Loading the Soy Milk Machine

I use a soy milk maker to cook and puree the beans to make the milk.

I load the beans, then the water into the machine, put in the heating element, and push the soybean button.

Step 3: The Milk's Done!

Once the machine has finished processing, filter the milk through a sieve to remove the okara (the solids left after cooking the milk) and your milk is ready to use to make tofu!

Step 4: Simmering the Milk

To make tofu, you will be adding magnesium chloride to the soy milk to separate the curds from the whey. The curds will be white clumps and the whey a light yellow liquid. This chemical reaction will not start unless the milk is at least 180 degrees Fahrenheit. To ensure that the milk is hot enough I bring it to a simmer on the stove.

Step 5: Preparing the Coagulant

Before adding the coagulant to the milk, dissolve 1/2 teaspoon of it in a cup of warm water if you are processing one quart of milk.

I used a microwave oven to heat the water, I put the measuring cup in the microwave for one minute on high power. Then I measured out and mixed the coagulant into the water.

The amount of coagulant (magnesium chloride) that you add to the milk will determine the texture of your tofu. I prefer a fim tofu, if you want to prepare silken tofu start with about half the amount of coagulant and add slightly more if needed to finish the chemical reaction that separates the curds and the whey of the milk.

Step 6: Adding Coagulant to Soy Milk

Now its time to complete the chemical reaction. I have included a series of photos during the separation process of the curds and whey.

Add the coagulant mixture to the milk slowly while stirring, and stop once you see that all the liquid is a light yellow clear liquid and there are not any milky sections of the liquid remaining. The reaction will occur fairly quickly with immediate evidence that it has started as soon as you add the first coagulant. If nothing seems to be happening, your milk is probably not sufficiently hot enough to complete the reaction. Turn up the heat on your stove and wait until you see clumping before adding any additional coagulant.

Step 7: Preparing the Mold

Once the curds are separated, you need to transfer them into a mold to squeeze out the remaining whey and push together into the a brick shape.

I used a tofu mold but any container can be used as long as it has some drainage on the bottom to allow the whey to drain.

I placed the mold into a bowl and lined it with cheese cloth. The bowl will catch the liquid that drains out of the bottom of the mold.

Step 8: Loading the Mold

Use a strainer to scoop the curds out of the pot into the mold.

Step 9: Pressing the Tofu

Fold the cheese cloth liner carefully over the curds, place the top of the tofu press onto the top of the liner, and add a heavy weight onto the top of the mold to press out the remaining whey. I chose to use my largest cookbook as a weight.

Step 10: All Done!

Your tofu is now finished, carefully remove your weight and the top of the mold to reveal a perfect block of fresh tofu! 

Now what to do with all that whey? Perhaps I'll use it as soup stock, make a batch of pancakes, or add it to smoothie.

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