Lights Out Tempeh Maker



Make Tempeh without a Temperature Controlled Incubator

Tempeh is a highly nutritious fermented soybean food from Indonesia. It has a somewhat nutty flavor and a firm texture. To make tempeh at home all you need are beans, some tempeh starter culture, and a warm environment. If you live in Indonesia the warm envirnment  is not a problem, but in my house, it is.


You can make tempeh at home without a temperature controlled Incubator, or even electricity, if you can heat water. You can use a 48 Qt. Insulated Picnic Cooler and a flat top Six Pack cooler. I used Coolers from Rubbermaid (Victory 48-Quart Cooler 3-Piece Value Pack---$40).  I made the 48 Qt Cooler Super Insulated by inserting 1"  foil faced insulating  foam board  arround the inside of the sides of the Cooler. You will also need  a calibrated thermometer. 





Fill the Insulated Six Pack Cooler filled with 7 1/2 quarts of 134'F (57'C) water. The hot water will bring the temperature of the 48 Qt. Cooler up to 91' F (33'C), from room temperture, in about 2 hrs. The Hot Six Pack Cooler will slowly release its heat into the Big Cooler over a period of hours. Because of the super insulation, the temperature will only slowly decay for 10 to 15 hrs. Then the growing mold in the tempeh will begin producing its own heat. The Cooler temperature should max out at 91'F (33'C). The fermenting tempeh will hold the beans at 89-90' F (31-32'C) for 36 to 48 hrs. You will need to experiment with the starting water temperature to get the temperature range of the 48 Qt Cooler correct. Do not exceed 91'F (33'C) for the initial temperature.


After 30 hrs, start checking the tempeh every couple of hours. Open the cover,quickley check the tempeh, and close the cover. Don't leave the cover open to long, the box  will cool quickly.  The beans should be covered with white mycelium. When you see dark gray mold spores around the vent hole, the bag of tempeh is mature and ready for harvest.



  1. Measure 2 cups of dry soybeans into a large pot. Cover with water and boil for 30 min. Remove the pot from the heat and allow to cool for 2 hrs.

  1. cooking

  2. Strain out the water. Use your clean hands to squeeze the beans through your fingers. Don't be gentile, you need to split the beans in half and loosen the seed coat. A potato masher will also do a good job.

  3. Flow cold water into the pot of split beans. Create a whirlpool of water. The seed hulls will tend to float in the moving water. I used a hose clamped along the edge of the pot to create a vortex. Use a strainer to skim the hulls out of the water. Give the beans another squish with the potato masher and repeat skimming. Repeat the process until you get most of the hulls skimmed off. It doesn't have to be perfect.whirlpool(2)

  4. Cover the beans with water in pot. Add 2 Tbs of White Vinegar. This insures an acid  environment to make the tempeh spores happy. Boil the de-hulled beans for 30 min. Skim off any hulls that pop up.

  5. Strain the beans and return them to the hot pot. Stir constantly until the beans are dry. The surface of the beans should look dull. Remove the beans to a dry towel and give them a good rubdown. This is a critical step, if the beans are to wet the tempeh starter will not take and the batch will fail.

  6. Transfer the beans to a large mixing bowl. Use the thermometer to measure the temperature of the beans. Wait until the bean temperature is below 85'F (29'C). Don't rush, high temperature will kill the mold. cooling(2)

  7. When the beans are cooled to 85' F, sprinkle 3/4 t of tempeh starter evenly onto the beans. Mix the starter into the beans thoroughly Spoon the beans into a 1 Gallon ZipLoc plastic bag. Spread the beans out evenly on a flat surface. Be sure to push them into the corners.

  8. Use an large needle (or small nail) to vent both sides of the bag. Punch holes every 1/2 inch (1 cm) . You need to allow air into the tempeh. You don't need to vent if you use a Ziploc Fresh Produce Bag.vent(1)

  9. Fill the Six Pack Cooler  with 134'F (57'C) water. Close the cover and place it in the bottom of the 48 QT Cooler. The hot water will bring the temperature of the cooler up to 91' F (33'C) in 2 hrs. or so.

  10. Set the cooling rack on top of the Six Pack Cooler in the 48 QT Insulated Cooler. Place something, like cardoard on top of the Sixpack Cooler to prevent direct contact with the Ziploc bag. Place the bag of beans on the cooling rack, close the cover and go away. Don't cheat and look in on the beans, you will mess up the temperature. Come back in 30 hrs and start checking your tempeh.finished(1)



Material List:


Rubbermaid  Coolers-Victory 48-Qt Coolers  Value Pack -----$40


1" Foil Faced Insulating  Ridged Foam-Dow Super TUFF-R-6.5



 Duck Tape  




10" x 10" Kitchen Cooling Rack


1 gal Ziploc bag




Tempeh Starter Culture - Cultures for Health                                                                                                                  









 Paul's Electric  Tempeh Maker PTM-7



The Tempeh Maker is made up of a modified Rice Cooker/ Steamer, and a Controller Box containing a 12 volt power supply, a peristaltic pump and reversible power switch. Use an accurate thermometer to adjust the “WARM” temperature, measured at the bottom of the Steamer Basket to 88 degrees Fahrenheit, using the temp knob. You can adjust the the Soak Time (4) to fit your schedule.You can soak for 8 to 24 hrs. Do not wait too long after the Cool Down (8) to Inoculate the beans. The beans are vulnerable to contamination. The slight air flow will provided necessary oxygen to the tempeh as well as keep positive pressure in the chamber to exclude airborne mold and bacteria. The steaming at the end will pasteurize the tempeh stopping the fermentation process.


1. Remove the Steamer Basket. Fill the Cooker pot with water to level 7 (brown rice scale). Add 1/4 cup of white vinegar to the water.


2. Place the plastic screen in the bottom of the Steamer Basket. Add 1 1/4 Cup of Hulled Split beans the the Steamer Basket. Use the 1/4 '' clear plastic weight tamp the beans down level.


3. Place the Basket into the pot. The beans should be covered with water. Install the cover and connect the dip tube to the pump. Connect the drain tube to the top fitting of the water storage container.


4. Allow 8 to 24 hrs soak time. Adjust the time to fit your sleep/work schedule.


5. Switch the Controller Switch to Drain for 40 min. This will draw the water down, leaving 1/2'' (1 1/4 cup) in the bottom of the pot. This will boil off making steam to cook the beans.


6. Press the “COOK” switch down on the Cooker. The Cooker will steam cook the beans for 30-40 min, and automatically trip the switch to “WARM” when the water has boiled off. The temperature in the cooker will slowly cool down to 88 F.


7. Wait 5 hrs for the temperature of the beans to cool to below 90 F.


8. Turn the Controller Switch to AIR. This will inject 40 cc of water back into the cooker to provide the nessisary humidity. The low flow of air provides oxygen  for fermentation, but not enough to dry out the beans.


9. Add the Tempeh Starter to the beans and mix thoroughly. Replace the plastic weight and tamp the beans level.


10. Incubate for 24 to 36 hrs.


11. Stop when gray spots appear at the vent holes in the plastic weight. Turn off the AIR switch.


12. To steam the finished tempeh, add 1/2 cup of water to the cooker pot. Press “COOK”. It will steam the tempeh for 15 min.


13. Store in Refrigerator for up to a week, or in the Freezer for up to 6 mo.






Paul Pepin