What is Tempeh?

Kirsten K Shockey

January 14, 2023

All the experts seem to agree that tempeh originated on the island of Java, one of over a thousand islands in the Indonesian archipelago. How it began is less clear, but we can assume that it likely grew out of either trade or war with a ferment-loving neighbor like China or Japan.

Tempeh is a delicious traditional plant-based protein that has been leveled up by fermentation. Traditionally it is made with soybeans but can be made with any legume or grain. For those familiar with koji it is similar in that it is also a fungi-based fermentation–just a different team. People across the planet are using their local ingredients and with this humble mold creating delicious sustainable food. But let’s back up a bit.

Tempeh made with black beans

(Photo by Kirsten K. Shockey)

All the experts seem to agree that tempeh originated on the island of Java, one of over a thousand islands in the Indonesian archipelago. How it began is less clear, but we can assume that it likely grew out of either trade or war with a ferment-loving neighbor like China or Japan. The Indonesians were likely introduced to soybeans, koji, and the process of fermenting soybeans with koji by the Chinese or Japanese. The Indonesians adapted the process to produce the tempeh we enjoy today. Similar to Chinese Qu, tempeh is brought about by diverse microorganisms, including fungi, yeasts, and lactic acid bacteria. In the case of tempeh, the mycelium rhizopus is the star player. From Java, where tempeh spread to the rest of Indonesia and Malaysia. The name became more generalized to refer to any fermented legume or cereal that mycelium had penetrated and bound together.

Fresh tempeh rhizopus

(Photo by Kirsten K. Shockey)

Rhizopus is both the common name and the genus name for a group of molds that, like most molds, are found in soil and plant material. Tempeh is most commonly made from one of two rhizopus species: Rhizopus oryzae and Rhizopus oligosporus, both of which are found in Indonesian tempeh. In Indonesia, tempeh makers who produce their starter traditionally do so by placing soybeans in fresh unwashed hibiscus leaves, as the fine hairs on the undersurface of the leaves contain the inoculant (the rhizopus fungus, plus a host of other microbes). Layers of leaves and beans are built and then bundled with rice straw. After a few days, the white mycelium appears, and the leaves are opened up and dried for another couple of days until they are covered with black spores. This dried starter is then crushed and sprinkled over soybeans. Traditionally, the inoculated beans are swaddled in banana or sometimes teak leaves, though today they are mostly fermented in plastic bags perforated with holes for air circulation.

(Photo by Kirsten K. Shockey)

The beauty of fungi-based fermentation, like koji and tempeh, is that it produces enzymes that penetrate the complex carbohydrates of starch, complex compounds of protein, and complex molecules of fat to begin to break them down into simpler molecules–simple sugars, amino acids, and fatty acids. This does two things. It makes the legume or grain more digestible and much more delicious. This is one of the reasons tempeh becomes a healthy plant-based protein that treads lightly on the planet. This type of fermentation also transforms soy. During tempeh production, antinutritional compounds are reduced by at least 65 percent, and in some studies, some of the antinutritional factors were reduced by as much as 90 percent. [[Frias 2017, Paredes-Lopez 1989, Jiménez‐Martínez 2007]]

Some people compare tempeh to tofu in that it is a soybean product that in many ways is a blank slate to any flavor the cook wants to add. However, while tempeh’s flavor profile can be designed by the cook, on its own, it has a toothsome texture and umami, that it brings to the dish. In this way, the flavors are amplified.

In the recipe below you can experience the umami squared as koji and tempeh work the magic. Tempeh and koji can be made at home. Still, if you are daunted by the idea you will find that tempeh has become readily available in recent years with the increased interest in plant-based foods. You will find the most selection at natural food stores. Koji can also be sourced premade. It is easily purchased at most Asian markets that carry Japanese foods. Look in the refrigerator or frozen food section. Here is an article that lists sources for finding koji online.

*The traditional spelling is tempe with angelized spelling adding the ‘h’ for pronunciation.

Plant-based Koji Tempeh Burger

(Photo by Kirsten K. Shockey)

This plant-based burger is juicy and delicious. You will use dried koji rice to make flour. You do this by putting it in a food processor or blender and grinding it to a powder. This powder is full of enzyme magic that will work with the enzymes in the tempeh to make the best burger.

Ingredients

7 grams (1 tablespoon) flax seed, finely ground
9 grams (1 tablespoon) black sesame seeds, finely ground
50 grams (1/2 cup) pecans, rough chopped
1/2 small onion (about 70 grams), chopped and lightly sauteed
3 garlic cloves, minced and sauteed

Prepare the above ingredients as directed and set aside.

227 grams (8-ounce block) tempeh, broken into pieces
60 grams (1/2 cup plus 1 tablespoon) koji flour
60 grams (1 cup) breadcrumbs
20 grams (1 tablespoon) shio koji
5 grams (1 teaspoon) vinegar
11 grams (2 teaspoons) tomato paste
125 ml (1/2 cup) oat milk or koji oat milk
Oil for frying

Directions

1. Prepare the first five ingredients as indicated and place them in food processor with the rest of the ingredients, except for the pecans. Process until paste-like, but not completely smooth. Mix the pecans in by hand.

2. Chill the mixture in a covered container for at least 3 hours or overnight.

3. Form patties and fry them in your favorite high-heat oil. You will fry at medium heat until crispy on both sides.

4. Enjoy!