Later On

A blog written for those whose interests more or less match mine.

Basic steps for homemade tempeh

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Black-bean-and-black-rice tempeh after four days.

https://www.tempeh.infoI update this post from time to time as I learn more from experience. Most recent update November 8, 2021, just to add this link:, a site with useful tempeh info — I definitely want to make the beluga lentil tempeh they describe. And their tempeh starter culture sounds first-rate — I plan to order some.

Tempeh is a traditional fermented Indonesian and Malaysian soy food prepared from soaked and cooked soybeans by salt-free aerobic fermentation using the mold Rhizopus oligosporus, a fungus. During the fermentation, the dense cottony mycelium produced by Rhizopus binds the soybeans together to form a compact cake. This page has a selection of excellent and informative articles about tempeh.

Tempeh has excellent nutritional value — much better than tofu, also made from soybeans, because tofu is more highly processed and to some degree refined. In terms of nutritional value, edamame (cooked fresh soybeans, a whole food) is better than tofu, and tempeh is better than edamame (because tempeh includes both the beans and the fungus mycelium).

I make Malaysian-style tempeh, with the soybean hulls left on. (Indonesian tempeh removes the hulls.) I leave the hulls on because (a) it’s easier, and (b) the hulls have nutritional value.

In my experience, homemade tempeh is much better than packaged tempeh I buy in a store — plus it’s satisfying to grow your own, as it were, and you can experiment by using different beans, boiled raw peanuts, cooked intact whole grains, or a mix. 

I started a while back, and I’ve gradually identified the success factors to the point that I can now make a good batch on purpose. Here’s a summary of my lessons learned and the method I now use:

  1. I often use soybeans, but you can use instead (or in addition) black beans, kidney beans, pinto beans, and so on. You can mix in cooked intact whole grain (spelt, kamut, brown rice, black rice, or the like) or boiled raw peanuts. Avoid using spices, many of which have anti-fungal properties (one reason they are used in making foods such as sausage: they act as a preservative).
  2. Cook beans without using baking soda or salt — use plain water.  (I had a series of failures until I realized that the baking soda was making the beans alkaline, and Rhizopus requires an acidic environment.) Cooking method: Soak beans overnight, drain soaking water using a sieve, then put the beans in a pot and cover well with water and simmer until done. I’ve found that beans are not so apt to boil over if I don’t cover the pot. However, with the pot uncovered, it is necessary to add water during cooking because of evaporation. I usually make a batch of 2 cups of uncooked beans.
  3. Rhizopus prospers in an acidic environment, and that is achieved by using vinegar (apple cider, white, brown rice, and wine vinegar all will work: the acidity is what’s important). You can choose between two times to add vinegar: (a) toward the end of cooking (for the last 15-20 minutes), in which case add 2 tablespoons of vinegar per cup of uncooked beans (thus I add 1/4 cup vinegar for my 2-cup batch) and continue cooking until beans are done; or (b) after the beans have been cooked, drained, dried, and cooled,  in which case use 1 tablespoon per cup of uncooked beans (2 tablespoons for my 2-cup batch).
  4. The best way I’ve found to dry the cooked beans is to drain them through a sieve and then spread them on a clean dishtowel. Using a paper towel, press the beans gently and rock them back and forth. You can also use a hair-dryer, but be careful not to get too close or the blast of air will blow the beans off the towel. Rhizopus likes a little moisture but definitely not so much that the beans are wet.
  5. Leave the beans on the towel until they’ve cooled. The common advice is to let them cool to 95ºF (35ºC), but it’s simpler just to let them cool until they are close to room temperature. Being cooler is not an issue, since they’ll warm up as you incubate them.
  6. After the beans have been dried and cooled, put them into a bowl. If you’re adding vinegar using method (b), add 1 tablespoon of vinegar per cup of uncooked beans. Then add either one packet of tempeh culture or — presumably — a chunk of tempeh from the previous batch. I still need to experiment with the latter.
  7. You can spread the beans in a layer in a flat glass dish, but I generally use a Ziploc fresh-produce bag because those bags are nicely perforated for ventilation. Also, if the beans are in a dish and unbagged, the mold results in fuzz that puts some off. In a bag, instead of a surface fuzz, the mold forms a velvety smooth coating like the boating on a Camembert. The Ziploc bags are also a good size for a 2-cup or 3-cup batch: if the beans are spread evenly through the bag lying on its side, so that the bag is filled side to side and top to bottom, the layer is a nice thickness. I like the thickness of the 3-cut batch, though often I will halve a slab to make two thinner slabs (not so easily done with a 2-cup batch).
  8. Incubation can be done initially in an oven on the proofing setting (if your oven has that) or in an oven with the light on and the door slightly open. For various reasons I decided to build my own tempeh incubator using rigid 1″ foam insulation board (sold in 24″ squares for projects; three of those square provide enough, once cut, to make an excellent incubator — details at the link). I lay the bag on a raised rack over a seedling warming pad (see link), whose thermostat lets me regulate the temperature.
  9. Incubate at 88ºF (31ºC) until Rhizopus is well started. This will take at least 12 hours and maybe 24 or longer. My most recent batch took 18 hours before the mold started to appear. Eventually you will see white patches of mold — it will look as though there are steamy spots inside the bag. At that point reduce the thermostat to 77ºF (25ºC) and allow the batch to continue to work for another 24-48 hours.

    For the first few batches I did not reduce the temperature, and as a result the mold spored, which results in dark grey or black areas. The tempeh is still good and perfectly edible, but some find the black spots off-putting. That hasn’t happened since I started reducing the temperature once the mold is established.

    Note: I found 3-cup batches were best removed from the incubator altogether — that batch size generates enough heat that it needs to be in the open air. Put the batch on a rack that holds it above the table. That transition generally happens after day 1. I go for 3 more days, 4 overall from start to finish.

    I’ve noticed that when the batch is out in the open on the rack, sometimes gray areas will appear on the bottom where the fungus has starter to spore. When I see that, I turn the batch (the slab in its Ziploc bag) over, and the gray areas are soon overgrown, white with a new mycelium covering. I usually turn the slab about every 8 hours.

  10. When you consider the batch done, remove the block of tempeh from the bag and cut it into pieces that will fit your storage containers and refrigerate it.

Regarding temperature

For a 2-cup batch (a batch made from 2 cups of uncooked beans), after initial incubation at 88ªF, I just reduce the thermostat to 77ºF and finish the batch. When I made a 3-cup batch (2 cups uncooked black beans and, cooked separately, 1 cup black rice), after the initial incubation at 88ºF, I found that it was best to remove it from the incubator altogether and put it on the table, on a rack that held it above the table, and just it go for the rest of the time — four days is what I usually do. See the discussion of temperature in this post. Update – The  3- cup batch came out fine.

Use in cooking

I usually cut off a piece and fry it like a hamburger patty in a little olive oil and use it to top a dish. If the piece is thick, I cut it in half to make two thin pieces. After frying a piece of tempeh, I sometimes cut it into squares to use like croutons in a salad. Or I dice the tempeh and cook with with a few chopped cherry tomatoes and onion chopped fine. You could sprinkle squares of fried tempeh with salt and some garlic powder to add flavor, or marinate them (see the recipe for tempeh bacon). I also make tempeh breakfast sausage and tempeh bacon. Sometimes I dice a portion and use the pieces in a stir fry, stew, or chili.

Here’s a 2-cup batch of soybean tempeh in process in my homemade tempeh incubator. The left photo was taken after about 12 hours at 77ºF (25ºC). I let it work for 24 hours more, and the result is shown on the right.

The difference between eating tempeh and eating mushrooms

At right is a piece cut from the above batch of soybean tempeh — the first batch where I knew exactly what to do and why. (The photo looks a lot like a candy bar, doesn’t it? But those are soybeans, not peanuts.)

The short, soft velvety coating is like the covering you see on Camembert, though the fungus on tempeh is Rhizopus oligosporus, and the fungus on Camembert (and Brie) is Penicillium camemberti. In either case, beans or cheese, the fungus colony forms a soft white crust. The job of Rhizopus, however, differs from that of Penicillium: the fluffy, white mycelium of Rhizopus welds the together beans to create an edible “cake.”

The fungus is why tempeh is more nutritious than edamame: with tempeh, you consume both the bean and the fungus mycelium. Note the difference between Rhizopus and the fungi we eat as mushrooms. When you eat mushrooms, you eat the spore-bearing bodies of the mycelium and don’t even see the mycelium, the actual fungus of which the mushroom is merely the “fruit” that bears the spores. In the case of mushrooms, the mycelium remains hidden underground — but when you eat tempeh, you eat the mycelium itself.

The Rhizopus sporing bodies don’t even appear if the tempeh maker knows what he’s doing (as I now do). They form when the tempeh is incubated at too high a temperature. Though edible, their appearance (black or dark gray) is off-putting to some. To prevent sporing, keep the incubation temperature at around 77ºF (25ºC) once the tempeh fungus colony is established. In the photo of the sample above, the snow-white mycelium is clearly visible.

Written by Leisureguy

8 June 2021 at 1:24 pm

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