A few years ago, I learned how to make tempeh at Sandor Katz‘s fermentation workshop in middle Tennessee. After seeing the process, it seemed like a lot of work, and I admit that I did not want to rush out and try it. But I’m glad I finally took the plunge!
What is tempeh?
Tempeh is an Indonesian bean cake, made by culturing (or more precisely inoculating) a legume, traditionally soybeans, but any bean will work, with Rhizopus oligosporus fungus spores, then incubating for 24 to 36 hours at tropical temperatures (85°-90°F/29°-32°C). Here’s where I get my tempeh starter. The fungus will propagate itself in and amongst the substrate (the medium on which the fungus grows and feeds– the beans and rice), consuming some of the protein in the beans, and taking the form of the container in which the tempeh is incubating.
What you do with it is up to you! Many people treat it like tofu– try marinating it in some soy sauce, rice vinegar, oil and chili paste for a half-hour before frying in some coconut oil. If you have an interesting recipe, please share it in the comments section!
Other Interesting Facts
Making tempeh is the same process by which mushrooms are cultivated. But most cultivated mushroom species we are familiar with (crimini, oyster, enoki) grow at cooler temperatures. And with mushrooms, we eat the fruiting portion of the fungus (the “above-ground” part) rather than the mycelium (the body, which with mushrooms is usually underground). With tempeh, we eat the mycelium and the substrate and do not wait for it to fruit. In fact, it doesn’t “fruit” like other mushrooms; rather it sporulates (creates spores) on its surface, giving it a black, blue or green splotchy look.
Note that tempeh is not a “lacto-fermented” food like sauerkraut or yogurt, meaning that there are no lactic acid bacteria or probiotic properties after you have prepared it. The “fermentation” refers to the process of propagating the culture (fungus) in the incubator. But there are many other benefits to eating tempeh, including beneficial enzymes, and the fact that the beans are more easily digestible (and nutrient-accessible) compared to cooked beans.
Batch #1: Chickpeas + Oven + zip-top bags
FIRST TIME: I followed the basic recipe from Sandor’s Wild Fermentation book, but also paid attention to the instructions from the starter culture I got from Cultures for Health, and took a few tips from Sandor’s new book, The Art of Fermentation. Note that tempeh is a cultured ferment, meaning that you need to add a specific culture to create it. (It will not spontaneously form the way that, say, sauerkraut would.
INCUBATOR: If you live in an area where the room temperature is between 85° and 90°F, then you don’t need an incubator. Room temperature around these parts is about 70°F and relative humidity 45%, so I needed to simulate the tropics. I put a $12 clamp lamp with a 60W incandescent bulb to generate heat at the bottom of my oven. If you have a pilot light or a bright oven light, often that will generate enough heat. I added a shallow pan of water to increase humidity.
I used chickpeas (aka garbanzo beans), which I had soaked for 24 hours in whey and water. I also mixed in some “dry-cooked” brown rice (another Sando-vation) into the substrate to absorb some of the residual moisture from the cooked beans.
The recipes call for hulling the beans (removing the skins) so that the mold can more easily get to the proteins. Being lazy, I didn’t bother with this step, although I did mash the beans and removed many of the hulls manually.
I kept the temperature between 87° and 91°F/30° and 32°C degrees throughout the incubation. It actually took closer to 48 hours for the fungus to fully bloom. Once dark grey/black spots form (indicating the fruiting phase), I knew it was ready and I removed it from the “heat.”
Finally, I removed it from the bags and let it cool to room temperature before refrigerating. I sliced it all and fried some right up! If you are not going to eat all of it within a few days, freeze the remainder. Slicing it before freezing lets you make a little at a time.
Batch #2: Dehydrator + banana leaves
DEHYDRATOR: This device is a good tempeh-maker! Even the most budget versions have a temperature control. Set it sucker to 95°F and fuggedahboudit! It’s brilliant at keeping air circulation and temperature constant throughout the process, making it a perfect tool for the job.
Banana leaves were originally used, and are common tools in southeast Asian cooking. For our second time, we went old-school after finding some beautiful banana leaves locally.
Second pass, we tried aduzki beans and barley as our substrate. It was a bit wetter than we wanted (barley is highly absorbent), so it took 55 hours in the dehydrator to fully develop. We suspect that if we started with a drier mixture, we can get that time down by at least 12 hours.
We learned not to mash the beans too much, as that creates a denser and wetter mixture. We want the substrate to be light enough to allow the mycelium to form. That requires cracks, crevices and crannies, so keep the beans as whole as possible.
- 1½ cups (dry measured) beans like soybean, chickpea or adzuki
- 2 Tablespoons liquid whey, pickle brine or lemon juice
- ½ cup (dry volume) brown rice or barley
- 1 packet of Tempeh starter
- Filtered water
- Check beans and remove any rocks.
- In a mixing bowl or large (half-gallon or gallon) jar, add beans, whey or lemon juice, and enough water to cover beans.
- Soak overnight or up to 24 hours.
- If using barley , soak barley in filtered water overnight or up to 24 hours.
- Drain and rinse soaked beans.
- Add beans to boiling water, and cook for ¾ the time (varies by bean type) you would if you were fully cooking them. You want them to be al dente (not quite fully cooked). You would cook adzuki beans for about 25-30 minutes.
- If using rice (not barley), follow normal cooking instructions, except use equal parts rice to water to make the rice 'dry'. (This is important to help absorb moisture from beans.)
- If making barley (not rice), drain barley from soaking water then add bring 2 cups water to a boil in a saucepan. Add barley and cook until it relatively dry (but not so dry that it sticks to the bottom of the pot and burns. Stir it frequently to avoid burning it.
- Drain cooked beans and pat dry with a dish towel.
- Transfer beans to a large mixing bowl. Mash lightly, just to loosen hulls. Add cooked rice or barley if using.
- Let mixture come down to body temperature (100°F/38°C), then add tempeh starter and mix thoroughly.
- Punch holes every inch into either two 1-quart or one 1‐gallon zip‐top bag (you are creating air holes for the tempeh to breathe.)
- Add mixture to bag(s).
- If using banana leaves, add a square or rectangular portion of the mixture about 1 inch thick to the center of the leaf. Fold the sides in (like you are wrapping a gift). Fold the ends in and use toothpicks to secure the ends of the "package".
- If using banana leaves, use a sharp knife to cut small (1/4 inch long) slits all on both sides and along the sides of each package.
- Create an environment where the temperature is consistently between 85° and 91°F (29°‐32°C), either an oven or a dehydrator. Use a thermometer with an alarm to ensure you stay in the safe zone.
- Place bag(s) in incubator.
- Check after 24 hours (unfold banana leaf package to inspect). Tempeh is ready when entire contents are white, indicating that the mycelium has enveloped the rice/bean mixture, and some dark grey/black spots start to form near air holes.
- If the mycelium has not fully developed, let it go another 12 hours, then check again.
- Remove from incubator and let cool to room temperature if refrigerating.
- Slice and freeze any portion you won’t eat in the next 3-4 days.