Wednesday, June 15, 2016

Homemade Tempeh

Homemade Tempeh

Okay, truth be told, tempeh is moldy soybeans. But what a mold! It is a completely vegan protein source made from minimally cooked soybeans that are delicious and highly digestible. The health benefits of tempeh are far beyond what I can list here. A good overview of tempeh from a health perspective is given in The World's Healthiest Foods. You can buy tempeh in any well stocked health food store for six dollars a pound or more. (1/14/24 edit: this was 7 years ago. It's probably much more now.) But you can make it yourself for less than one dollar a pound. Tempeh is a staple food in Indonesia.


  • 2 lbs dry uncooked organic non GMO soybeans (1/14/24 edit: My current recipe uses 400 gms, about 9/10 of a pound)
  • 1 tablespoon rice vinegar (1/14/24 edit: I am now using 1 T of white vinegar. Either is probably fine.)
  • 2 teaspoons Tempeh Starter (my source is (1/14/24 edit: Since moving to Mexico, I use this as my source of starter: This package is sufficient for 21 batches of 400 grams each, a total of about 18 kilos of finished tempeh. Note that the price is in pesos, which works out to about 55 USD at current exchange rate.)
  • Water as needed

Things You Will Need

  • A large soup pot
  • Large colander
  • Cup measure
  • Sandwich baggies
  • Qt Freezer bags (gallon would be even better)
  • Small bowl
  • Teaspoon measure.
  • Two clean bath towels
  • Digital thermometer 
  • An incubator arrangement (I use a folding bread proofer from The incubator must hold a constant temperature of 85-90 degrees F. (1/24/24 edit: I now use a incubator. My current starter instructions recommend a temperature of 30 degrees C, about 86 degrees F, so I set my incubator for 30 degrees C, +/- .5 degrees C.)
  • Counter space large enough to lie a bath towel on.
  • Toothpick


To make tempeh, we do a highly controlled molding of soybeans using a specific type of mold that is indigenous to Indonesia. The mold we use is a combination of two strains, Rhizopus oryzae and Rhizopus oligosporus. If you buy the tempeh starter from my source ( , you will be getting mold spores of these two strains. (1/14/24 edit: My current Mexican source contains only Rhizopus oligosporus.)

There are three stages to tempeh production:
  1. Preparation of the Soybeans
  2. Inoculation of the Soybeans
  3. Incubation of the Soybeans

Stage One: Preparation of the Soybeans

Add dry uncooked soybeans to soup pot. Add plenty of water to pot, at least 3X the amount of soybeans.

Bring to a boil. Turn off heat and leave covered for 10-14 hours. If the soybeans start sticking their heads above the water, add more water.

Dehull the soybeans. The soybeans are covered with a hull that must be removed to allow the mold spores to penetrate the beans. To dehull the soybeans, take hand fulls of soybeans and squeeze them in your hands. Drop the beans back in the pot and pick up two more hand fulls. You will notice the hulls floating at the top of the water in the pot (not to mention sticking to your hands). Every once in a while, pour off the hulls and replace the water. It will take you about 5 minutes of squeezing to dehull two pounds of soybeans. When you are finished, pour off as many of the hulls as you can, but don't worry if you miss some.

Add rice vinegar (1/14/24 edit: or white vingegar) and enough water to cover the soybeans by at least two inches. Bring to a slow boil and boil covered for 30 minutes. More hulls will now float to the surface. When the soybeans are finished boiling, you can pour them off. If a few are left with the soybeans, don't worry about it.

Drain the cooked soybeans into a colander. Pour all of the beans and water out of the soup pot. Leave any remaining soybean pieces in the pot but pour all of the liquid out. Let the colander thoroughly drain. Put the drained soup pot aside to cool off.

Pour the soybeans from the colander onto the first towel. It is important to dry the soybeans as much as possible, since wet soybeans encourage undesirable mold growth. Move the soybeans around on the towel with a wooden spoon or rubber spatula and rub the soybeans with the towel.

Cooked Soybeans Drying on Towel
Pick up the towel by the edges and pour the soybeans onto the second towel. Rub the beans all around until they feel dry to the touch. It will take two towels to dry two pounds of cooked soybeans.

Let the soybeans completely cool. This is important, because if the tempeh starter comes in contact with hot soybeans, the starter will die.

Stage 2: Inoculation of the Soybeans

Now we are going to introduce the soybeans to the mold. Add tempeh starter to small bowl. (1/14/24 edit: my current source packages the spores in an envelope, so I add them directly to the soybeans.)

Tempeh Starter in Small Bowl
Return the cooked soybeans to the cooled soup pot along with any particles left in the soup pot. Note: The soup pot should have been completely dried and cooled at this point.

Sprinkle 1/5th of the starter at a time over the soybeans in the soup pot, stirring well after each addition. You want to thoroughly mix the starter into the soybeans.

Add about 2 cups of soybeans to a sandwich baggy. Squeeze out air, flatten soybeans, and zip lock the baggies. Final thickness of the soybeans in each baggy should be 1 to 1 1/2 inches. Repeat until all of the soybeans are in baggies. Final baggy may not take a full 2 cups, just add whatever you have left. Fold the last baggy as needed to make a thickness of 1 to 1 1/2 inch.

Soybeans in Baggies

Place flattened baggies of soybeans in freezer bags. You can get 2 baggies in a quart size, probably all of them in a gallon size.

Store freezer bags in freezer. They will last for months. (1/14/24 edit: Since I am now doing smaller batches, I don't store the bags in the freezer, but go directly to the incubation stage.)

Take the towels outside to dry. Once dry, you can shake off the many particles of soybeans that will adhere to the towel which will make cleaning your kitchen much easier.

Stage Three: Incubation of the Soybeans

Remove one or two bags of inoculated soybeans from the freezer. Let them completely defrost and come to close to room temperature. (1/14/24 edit: Or just take the bags directly from the last stage.)

Wipe all of the moisture that has condensed on the baggies off with a towel. Get the baggies as dry as possible. Dry both sides of the baggies. We don't want any of the nasty moisture annoying our friendly mold.

Take your clean toothpick and puncture the baggy about 20 times on each side. About every inch of baggy should have a puncture. This will allow air into the baggies for the growing mold to breath.

Place your baggies in your incubator and set the temperature to 88 degrees F. The temperature can vary by +/- 2 degrees. If the temperature exceeds 95 degrees F, the mold will die and the tempeh batch will be lost. (1/14/24 edit: I now set the incubator at 30 C +/- .5 degrees C.)

Place your thermometer on top of one of the bags of soybeans. This will allow you to monitor the temperature of the beans. Adjust the temperature of the incubator as needed to maintain a bean temperature of about 88 degrees F. (1/14/24 edit: My current incubator is very accurate and includes a built in thermometer, so I no longer need the extra thermometer. I built the incubator myself. You can find the plans here.)

Beans at 0 Hours Incubation
When first placed in incubator, we just see a bag of cooked soybeans at room temperature.

Beans at 12 Hours of Incubation
After 12 hours of incubation, we can see the distinct presence of mold. Around now, the fermentation process will start producing considerable heat. You may need to adjust the temperature of the incubator much cooler so the bean temperature doesn't exceed 88 degrees F. I have turned my proofer down to 77 degrees F to keep the bean temperature at around 88 degrees F. (1/14/24 edit: If your incubator is accurate, it will automatically adjust for the change in bean temperature.)

Beans at 24 Hours of Incubation
After 24 hours of incubation, the beans are almost covered with the mold. Notice that the temperature is a little high, so I adjusted the proofer down two more degrees.

Beans at 35 Hours of Incubation
At 35 hours of incubation, the beans are a solid cake and the mold looks like white cake frosting. Your times may vary depending on conditions and temperature. The heating of the beans has slowed down so the temperature of the beans is actually a little low, but better too low than too high. The tempeh is now done.

The baggies can be cut off of the beans and you will have a nice solid cake of beans that can be cooked according to any tempeh recipe.

Finished Tempeh
Good tempeh is a solid white mass of mold holding the beans together. There may be some grey specks due to mold spores which are harmless and may even add to the taste. You can pick up the tempeh by an edge and it will hold together. It should smell pleasing, like fresh mushrooms. If the tempeh has large loose areas, crumbles when you pick it up, and smells unpleasant, then the tempeh went bad and should be discarded. It probably was too wet or got too hot.

Tempeh can be stored in the refrigerator for three days. If it will be stored longer, slice it and freeze the slices. It is best fresh which is why I like to prepare many baggies so that I can incubate frequently in small batches.

Store brought tempeh can be stored much longer in the refrigerator. This is because they steam treat the tempeh to kill the mold before packaging. This improves storage times and makes shipping easier but gives the tempeh a distinctly stale taste. Your tempeh will not keep as long, but will taste infinitely better. And it will cost about one fifth as much.

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