Tempeh and tofu are both versatile vegan protein sources made from processed soy beans. Even though tempeh and tofu both originate from the same plant, they undergo two different processes to result in distinct products. The less processed option is tempeh, which tastes slightly nutty, is higher in protein and fiber, and has a firmer, drier texture than tofu. Tofu is smooth and almost tasteless, and is packed in water to keep the product moist. Both tempeh and tofu are common substitutions for animal protein in vegan and vegetarian cooking.
The differences between tempeh and tofu stem from how they are made. To make tempeh, cooked, shelled soybeans are fermented with a bacteria or culturing agent. Homemade tempeh can be produced by purchasing a tempeh starter that contains the correct strain of bacteria for the fermenting process. Fermenting soybeans to make tempeh is similar to introducing live cultures to milk to make yogurt. After holding the soy and bacteria mixture at a temperature of approximately 86 degrees Fahrenheit (approximately 30 degrees Celsius) for about 24 hours, the tempeh is complete.
While making tempeh is analogous to the yogurt making process, making tofu is analogous to cheese making. Instead of fermenting whole soybeans like with tempeh, tofu is made by curdling soymilk and compressing the curds into blocks. Fresh soymilk is mixed with a thickening agent called a coagulant and then heated until the milk curdles. The curds are collected and separated from the excess liquid and then pressed into cakes or blocks. Tofu is available in several different textures ranging from the softest silken tofu to the most dense and solid extra firm tofu.
Some very noticeable differences between tempeh and tofu are the taste and texture. While both products are mild, tempeh boasts a slight nutty or earthy flavor. Contrarily, tofu is almost completely bland and tasteless. Both tempeh and tofu rely on the other ingredients they are cooked with for flavor, and act like sponges to absorb the seasonings or sauces they are prepared with. Generally, tempeh has a firmer and drier consistency, whereas tofu is smooth and moist and must be stored in water to prevent it drying out.
Even though both tempeh and tofu are significant sources of protein, tempeh generally has more protein since it is derived directly from soy beans, not soy milk. Similarly, tempeh also has more fiber than tofu because it is less processed and made from the whole beans. In terms of calories, tofu is almost half as caloric as tempeh, but both still have less fat and calories than their animal protein counterparts.
Tofu can be packaged and purchased two ways. Silken tofu is often packed tightly in cardboard without water and stored at room temperature. Firm and extra firm tofu are usually found in small blocks submerged fully in water to prevent drying. Tempeh is generally sold in flat strips approximately 8 inches (about 20cm) long.