Botanical atlas
Tempeh Mold
Rhizopus oligosporus
Rhizopus oligosporus is the living heart of tempeh, the firm, nutty soy cake that has fed the people of Java for centuries. Cooked, dehulled soybeans are inoculated with this mold and left to incubate, and within a day its white mycelium knits the beans into a single dense cake that can be sliced, fried, steamed, or simmered into soup. Long before refrigeration or industrial food science, Javanese cooks understood that this humble mold turned a plain legume into something more digestible, more flavorful, and remarkably shelf stable when kept properly. It remains one of the world's most successful traditional fermentations, prized as an everyday source of nourishment across Indonesia and, more recently, in kitchens worldwide.
In tradition.
Rhizopus oligosporus is the living heart of tempeh, the firm, nutty soy cake that has fed the people of Java for centuries. Cooked, dehulled soybeans are inoculated with this mold and left to incubate, and within a day its white mycelium knits the beans into a single dense cake that can be sliced, fried, steamed, or simmered into soup. Long before refrigeration or industrial food science, Javanese cooks understood that this humble mold turned a plain legume into something more digestible, more flavorful, and remarkably shelf stable when kept properly. It remains one of the world's most successful traditional fermentations, prized as an everyday source of nourishment across Indonesia and, more recently, in kitchens worldwide.
Traditional preparations.
The classic Javanese method of turning soybeans into tempeh using Rhizopus oligosporus as the fermenting culture.
Soak 1 cup dried soybeans overnight, then dehull and cook them until just tender. Drain thoroughly and spread the warm (not hot) beans on a clean towel to dry the surface. Sprinkle in a small pinch of Rhizopus oligosporus starter powder per the package instructions and mix well. Pack the beans into a shallow perforated container or banana leaf parcel about half an inch thick, and let it sit undisturbed in a warm spot, around 86 to 90°F, for 24 to 36 hours, until it is bound into a firm white cake.
Safety.
This mold is safely used to make tempeh, but ferments should come from a reliable starter and be well cooked, since related Rhizopus species can cause serious infections in people with weakened immune systems.
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