Above: Image © Xiangdong Li, iStockphoto

I like to think that everyone remembers the first time they encountered tofu. I clearly recall my mother serving up four flavourless blocks onto my plate. She insisted that I “just try it.” At the time, I was disgusted. The tofu looked like opaque, jiggly ice cubes. But since then, I have given tofu a second chance.

How about you? Do you think tofu is as exciting as Pokémon Go coming to Canada? Or do you secretly refer to tofu as “toad-food?” Either way, you’ll probably think it’s pretty neat once you hear how it’s made!

Step one: Soybeans

You might already know that tofu comes from soybeans. Soybeans are legumes. And legumes are a pretty incredible group of plants. Why?

Well, legumes have round structures in their roots called root nodules. These structures contain a type of bacteria called rhizobia. The soybean plant gives the bacteria a home. In return, the rhizobia give the plant nitrogen, which it needs to grow.

So it is partly thanks to these little organisms that legumes can grow at all! Also, with the help of their little bacterial minions, the soybean plant produces bean-like fruits that contain hard, round seeds: soybeans!

Did you know? Soybeans were domesticated in China about 5000 years ago. But they didn’t become common in Europe and North America until the 1900s!

Step two: Soy milk

To turn soybeans into tofu, you have to soak dry soybeans for at least three hours, then grind them up with water. Gross, right? Hold onto to your tofurkey—it gets better!

Now, boil the blended beans and water. Then, filter out anything insoluble—mainly leftover chunks of bean. Voilà: you now have soy milk! Your next step is to get from liquid soy milk to solid tofu.

Step Three: Choose your type of tofu

Two main types of tofu are made in North America: silken (soft) tofu and momen (firm) tofu. Both types use a salt or an acid to make the soy milk coagulate (solidify).

Salts are compounds that result from the reaction of an acid and a base. The hydrogen in the acid gets replaced by a metal or a cation (a positively charged ion). Some examples of salts used to make tofu are magnesium chloride (MgCl2) and and calcium sulfate (CaSO4). An example of an acid used to make tofu is glucono delta-lactone.

If you’re after silken tofu, the process stops there. But if you’re going for something a bit meatier, there’s one more step: you have to break up the curd, which is the solidified soy milk resulting from the coagulation process. You then have to press the broken-up curd into a firm cake, which reduces its liquid content. The result: momen tofu.

Did you know? Since soybeans have more protein than corn, they’ve gained popularity as feed for livestock. Today, most farm animals eat soybeans instead of corn!

Tofu and your health

It’s pretty impressive that people have been able to figure out all the steps that go into making tofu. But why bother? Is it even good for you?

Well, some research results suggest that soybeans and soy products can decrease the risk of heart disease and some cancers. Plus, soybeans are about 45 percent protein (tofu is about seven percent), so they can be an important part of your diet. Soybeans are also a good option for people who want to be kinder to the environment, since plants take less energy to produce than meat.

With that said, eating too many soybeans may be dangerous for your health. Soybeans contain isoflavones, compounds that mimic the human hormone estrogen and can affect bodily processes. Scientists aren’t sure yet whether isoflavones can cause health problems for humans. As with most things, a good rule is to eat soy products in moderation!

Tofu or “toad food”?

So, soybeans are legumes that can be processed in different ways to produce different types of tofu. Tofu can be delicious, good for the planet, and good for you when you eat it in moderation. Now that you know all of these cool things about making tofu, what do you think? Should you give poor old tofu another chance?

Learn More!

About soybeans and tofu:

Magic beans (2000)
V. Smil, Nature 407

Tofu
Encyclopædia Britannica

About the impacts of eating soybeans and tofu:

What Is Tofu? Health Benefits, Concerns And Recipes (2015)
R. Moss, The Huffington Post UK

Isoflavones: chemistry, analysis, functions and effects on health and cancer (2014)
K. Ko, Asian Pacific Journal of Cancer Prevention 15

Emily Beaton

Growing up in Ottawa, I always had a love of nature, so it made perfect sense to study Biology in university. I earned my bachelor's degree in May 2016 from Mount Allison University in New Brunswick, where I participated in research on Lyme Disease and little brown bats. While completing my minor in History, I became increasingly interested in how the past has influenced how we understand and do science today. This year, I am beginning a master's in the History and Philosophy of Science and Technology, which is a perfect fusion of my two main academic interests. When I'm not engrossed in a good book or playing board games with friends, you can probably find me typing out a word or two beside my pet snail, Biscotti, who is the best writing companion a girl could ask for!







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