Home Soy foods Soy and your health Recipes with soy Make natto Make tempeh Soy news

Tempeh Starter

As with other fermented products such as yogurt, miso, natto, or kambucha, a starter is needed to begin the fermentation process. Without a good starter, other microorganisms will spoil the product, making it inedible or even toxic.

In Indonesia, tempeh starter was traditionally made by wrapping cooked soybeans in hibiscus leaves, which naturally contain the desired Rhizopus molds, and letting it ferment in a warm place for a few days. This method resulted in tempeh containing a variety of fungal strains such as R. achlamydosporus, R. formosaensis, R. arrhizus, R. oryzae, R. delemar, R. microsporus, and R. stolonifer. Unfortunately, Indonesian tempeh producers don't use this method anymore. Instead, they use a commercial tempeh starter that contains only one strain, R. microsporus (=oligosporus).

It is also possible to make tempeh from a piece of very fresh living tempeh by chopping it up and adding it to the cooked and cooled soybeans. However, this method is not very reliable and in practice often results in a bad batch. As a result, most tempeh manufacturers, even large factories, use commercial tempeh starter, which is guaranteed to be strong and free of unwanted bacteria such as Escherichia coli, Salmonella or Listeria.

Where can I buy tempeh starter?

A good source for tempeh starter is TopCultures or Tempeh.info. If you are looking for a soy-free tempeh starter, you can use this oncom starter. Although it is sold as an oncom starter, it can also be used as a tempeh starter. It seems to work very well with high starch beans such as lentils and peas. I would not buy tempeh starter from Amazon, Ebay, or Etsy because these companies do not verify that the seller is an authorized food company. You will find products that do not meet current safety standards.

Make your own tempeh starter

If you want to make your own tempeh starter, you can follow the procedure used by the University of Illinois.

1. Preparing the substrate

Place 1/4 cup long grain white rice in a pint mason jar and add 20 ml water. Shake the jar to mix the rice and water. Cover the jar with a wadding lid made by placing layers of wadding between two layers of cheesecloth. Secure the lid with a rubber band or by replacing the metal ring. Allow to stand for several hours, swirling occasionally.

2. Sterilization

Use an autoclave or pressure cooker at 15 psi and 121°C for 15 minutes. While still hot, shake jar vigorously to break up rice clumps and allow to cool to room temperature.

3. Inoculation

Prepare a spore suspension by aseptically adding a few ml of sterile water to an agar slab of Rhizopus oligosporus or Rhizopus oryzae. Aseptically add the spore suspension to the rice and mix well.

4. Incubation

Incubate the jar on its side at 30°C (86°F) for 45 days, at which time the rice will be covered with mycelia and black spores.

5. Harvesting the spores

Transfer the contents of the jar to a sterile blender and blend to a fine powder. This tempeh starter can be frozen to maintain viability.

Contaminated Tempeh Starter

Good tempeh starter is expensive, but some suppliers don't take hygiene seriously and sell product that is not pure and may even be contaminated with pathogenic bacteria. Contaminated tempeh starter was recalled in April 2012 after an outbreak of a rare type of salmonella sickened more than 90 people, mostly in North Carolina. The infections were spread by eating the fresh tempeh, touching surfaces contaminated by the product, and person-to-person contact. The FDA traced the contamination to Tempeh Online, a Rockville, Maryland-based tempeh starter distributor that imported its product directly from Indonesia. At the time, Tempeh Online operated several websites. Before purchasing tempeh starter, make sure you know the location and reputation of the original manufacturer.