Key findings
- 1Tempeh fermentation by Rhizopus oligosporus mold breaks down phytic acid and partially hydrolyzes the soy protein, and the culture is the only thing added
- 2Unlike tofu, tempeh uses the whole soybean including fiber; nothing is discarded during processing
- 3At three ingredients (soybeans, water, culture), tempeh is one of the simplest and least processed plant protein sources in the grocery store
Why is Tempeh Level 2 on average?
Tempeh originated in Java, Indonesia, possibly as early as the 17th century. The production process is remarkable in its simplicity: soybeans are soaked, dehulled, partially cooked, mixed with Rhizopus oligosporus spores, and incubated at 30-35C for 24-48 hours. During fermentation, the mold's white mycelium grows through and around the beans, binding them into a solid cake. The fermentation changes the beans chemically rather than adding to them: Rhizopus enzymes break down phytic acid, partially hydrolyze the soy protein, and synthesize B vitamins. Nothing is added but the culture. Unlike tofu, which discards the fiber-rich soybean solids, tempeh uses the whole bean. In our analysis, tempeh averages a Processing Score of 3.1, which is Level 2.
How 28 tempeh products break down
Share of products at each processing level, in our analysis.
Tempeh brand comparison
From least to most processed in our database.
How to read a tempeh label
- 1
Basic tempeh lists three ingredients: soybeans, water, Rhizopus oligosporus culture
- 2
Multi-grain tempeh adds other beans, grains, or seeds, and stays a short, simple list if there are no preservatives
- 3
Marinated or flavored tempeh adds soy sauce, seasonings, and sometimes preservatives, which makes it more processed
- 4
The white mold growth between beans is the Rhizopus culture; it is supposed to be there
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Frequently asked questions
Is tempeh healthier than tofu?
From a processing standpoint, tempeh is marginally less processed than tofu. Tempeh uses whole soybeans while tofu discards the fiber-rich solids. Both are simple plant proteins.
Is the white mold on tempeh safe to eat?
Yes. The white mycelium is Rhizopus oligosporus, and the fermenting culture that defines tempeh. It is not contamination. Black or gray spots can also be normal spore formation. Only avoid tempeh with unusual colors (pink, yellow, green) or off smells, which indicate unwanted mold contamination.
Is tempeh better than Beyond Meat for plant protein?
From a processing standpoint, dramatically. Tempeh has three ingredients and a long history. Beyond Meat lists many more ingredients and relies on novel food technology; search Beyond Meat to see its own average. Both provide plant protein, but tempeh achieves it through ancient fermentation rather than industrial engineering.