This is what makes tofu, tofu.
Over half of Americans are trying to eat more plants and less meat, whether to fight climate change, improve their health, or boycott factory farming. Yet, despite growing demand for plant proteins, American tofu is a monolith.
Most mainstream grocers carry just 3 varieties — firm, soft, and silken — and none of these varieties are particularly well-suited towards grilling, dry-frying, and other western cooking techniques. As a result, many home cooks are confused as to what tofu is, what varieties there are, and how to use them.
This first post will about what tofu is. (The next two will focus on varieties and uses.)
Just as cheese is curded cows milk, tofu is curded soymilk.
The most basic tofu making process is as follows:
1) Grind dried soybeans into soymilk
2) Cook that mixture to inactivate anti-digestive enzymes
3) Strain out soybean pulp
4) Add in coagulants to curdle the soy proteins, resulting in curds
5) Press the resulting curds into a desired form
6) Finish with any additional processing.
While this process sounds simple, there are actually many varieties. China alone has over 27 distinct types of tofu. To understand how different each variety is from the others, consider the following variables.
1) Curdling — the coagulant used to trigger the curdling process has a big effect on the tenderness of the curds, curd size, flavor notes, and water content. Other factors include amount of coagulant added, speed of adding coagulant, and soymilk temperature.
2) Pressing — time and pressure of pressing impacts water content, firmness, and beanyness. Some methods break up curds into smaller size, which allows them to be pressed into thin sheets, as opposed to blocks.
3) Post-press processing — after pressing, tofu can be processed in many additional ways. Fermentation using healthy bacteria strains can produce a wide range of aromas and textures. Salting or seasoning, with table salt, MSG, or alkaline salts, can contribute to different flavors, chewiness, and cooking properties. Drying and then reconstituting, either with water or by frying, as well as freezing fundamentally alter the internal structure. Smoking affects dryness, firmness, chewiness, aroma, and shelf life.
4) Water/bean cultivars/heating mechanisms — heating the soymilk by wood-fire, gas, and coal all produce vary different flavor notes. Different bean cultivars and water mineral contents also have a major effect on flavor.
5) Other beans/legumes — varieties using soy protein instead of whole beans have far less beanyness and more chewiness. Others, using legumes like chickpeas or peanuts, result in starch-curded tofu, which has its own special characteristics.
As you can see, tofu production involves many variables, each of which has a large impact on flavor, texture, form, and culinary uses.
Our next post will go in-depth on some of China’s 27 varieties of tofu and their major differences from what we have in the States.