Frequently Asked Questions

How do I store tempeh starter?

tempeh-starterTempeh starter should be kept in the refrigerator (2 - 6°C) in a closed glass jar.
When you open the fridge warm most air will enter the fridge and will condense on the objects in the fridge. In the glass jar the tempeh starter is protected and won't get wet.
For optimal storage it's recommended to put some silica-gel (dehydrator) in the jar. This can be ordered at your local pharmacy. You should ask for the orange type which is not toxic, as opposed to the blue type which contains cobalt. When the gel is saturated the orange colour will disappear and the gel should be regenerated by placing in an oven at 110°C during 1 hour.

How do I store homemade tempeh?

Fresh tempeh can be kept in the refrigerator (2 - 6°C) for about 10 days. Frozen tempeh keeps well for several months.

How much tempeh should I eat daily?

There's is no minimum or maximum amount. We only advice that tempeh is part of a well balanced diet. The FDA recommends to consume daily about 25 g of soy proteins. This corresponds to 125 g tempeh.

What soybean varieties are suitable for the production of tempeh?

There are no specific varieties which should be used for the production of tempeh. Soybeans which are bigger should be preferred because they are easier to dehull and easier to dry (less surface). Also they give a better looking tempeh.

Can I eat raw tempeh?

Raw tempeh is intended to be cooked to an internal temperature of minimum 80°C (176°F) for a minimum period of 60 seconds. After handling raw tempeh you should wash your hands and all surfaces, cutting boards, knives and utensils with soap and hot water. Tempeh manufacturers that sell raw tempeh must inform their clients about above safety measures, for example by mentioning it on the label.

How do I know that my tempeh is good?

In fresh tempeh the soybeans should be bound together into a tight cakes with no mold growing other than the white tempeh culture. Small black spots may occasionally appear. These spots do not necessarily indicate spoilage, but are part of the tempeh culture's life cycle.
The texture should not be slimy and the aroma should be mushroom-like (or yeast-like). A every slight smell of ammonia is normal. This smell will increase if you incubate too long, indicating that the proteins have been broken down too much.

My batch of homemade tempeh is spoiled, who can I prevent this in future?

There could be many reasons but the most important one is the incubation of moist beans. Then alien organisms will grow and compete with the tempeh mould. This will result in a slimy texture and off-flavor.
Other reasons could be:
- using old or inactive starter(starter should be kept in a dark, cold and dry place)
- working under unhygienic conditions
- too high incubation temperature which kills the mold (temperature should be 28 - 32°C).

Molds can produce toxins! How safe is tempeh?

The molds (Rhizopus) used for the production of tempeh are eatable and don't produce any known toxins. There have been no reports of serious illness after eating of tempeh.

My tempeh starts to sporulate! Can I still use this tempeh?

Around the holes in the plastic, where there's a lot of oxygen, the molds will produce some black spores. This tempeh is still eatable.
Depending on the Rhizopus strain this will happen already after 24 hours of incubation or only after 3-4 days of incubation. The Rhizopus strain you can order on this website does not produce black spores during the normal incubation period of 36-48 hours.

Why are the hulls not used in tempeh making? They provide good fiber. If I were to make my own tempeh leaving the hulls on would it not work?

Yes, you can make tempeh without removing the hulls. But the rhizopus mold cannot grow through the hard hulls. You need at least to break the hulls (split or crack the beans) so the mold can reach the inside of the beans. If you keep the hulls the quality of tempeh will be a bit lower and it will be more difficult to remove excess water resulting in higher spoilage risk.