Tempeh has gotten very popular in the last few years and most supermarkets will carry it in their organic or natural food sections. If you have never tried it, Tempeh is made of soybeans that have been cultured with a fungus (Rhizopus oligosporus) forming white solid cake like ferments with a nutty and earthy flavor. They make excellent meat substitutes. The fungus also increases the digestibility of the soybeans through various metabolic processes. Why make it at home if you can buy it in the store? The homemade version is so much better tasting and who wouldn’t want to grow a fungus in their own home.
The process is actually pretty simple.
- soak soy beans
- cook soy beans
- dry soy beans
- inoculate with tempeh starter
- ferment at 85-90 F for 24-48 hours
- eat tempeh
We break it down for you a little more below:
Step 1: Soak the soy beans. 12-24 hours is usually adequate. A little less in the summer, a little more in the winter due to the ambient temperature. This is also your de-hulling step. Soy beans come with hulls that come off after soaking. Agitate the beans with your hands and pour off the water. The hulls are lighter and will float on top. You may have to repeat this step a few times. No need to remove all the hulls, but you should get the majority of them off.
Step 2: Cook the soy beans. The idea is to keep the beans slightly undercooked so they don’t get too mushy when you handle them. In this batch, I ended up overcooking them. Still works, but is not optimal. I find 10 minutes in the pressure cooker is the right time after a long soak, but you will have to find out for your own pressure cooker.
Step 3: You need to dry the beans. Wetness is the mortal enemy of the fungus as bacteria will take over in a wet batch. You have two options here.
- Dry with a hair dryer
- Pat down with a towel
Step 4: After your beans are dry, you are ready to inoculate them with a starter. I picked up my starter at the local Indonesian store. There are no labels on it, no instructions, no identification; so if you have an Indonesia store, go ahead and ask to be pointed toward it.
Mine looks like it was made in someone’s house .. they also sell homemade tempeh. There are also various sources on the internet if you cannot obtain the starter locally. At this stage, you will also add in some vinegar. This will lower the ph which won’t hurt the fungus, but will make the beans less hospitable for bacteria. For 1 pound of beans, add 2 teaspoons of vinegar and 1 teaspoon of starter.
Step 5: Prep the freezer bags you will be using to pack the soy beans. You need to put numerous holes in it (think maybe 7 by 7). The fungus needs air to grow and metabolize.
Step 6: Pack the inoculated beans in the freezer bags – they are ready for fermentation.
Step 7: Let’s take a little detour to talk about the fermentation container. I use a large Styrofoam cooler. Heat is generated by a small night light with a 5W bulb that rests in a glass bowl (you don’t want it melting the Styrofoam). I also have several bamboo sticks inserted to make trays for the freezer bags – remember they need to have access to some air. Lastly, a thermometer allows me to check the ongoing temperature – it should stay between 85-90F.
Step 8: Take a peek at around 12 hours of fermentation time. At around the 12 hours mark, the fungus starts to generate its own heat. Don’t be surprised if the temperature moves up by 5F or more. You can cut off the heat source if needed. The tempeh cakes should be ready in 24-48 hours.
Step 9: Enjoy. Freshly made tempeh only lasts for a few days in the refrigerator, so freeze any tempeh that you will not consume in the next few days.
Below is a video of the process