page_title: Tempeh
section_title: Production
hierarchical_section_title: Tempeh / Production
caption_attribution_description: English: Making tempeh by wrapping boiled soy beans in banana leaves. Bahasa Indonesia: Membungkus tempe dengan daun pisang.
context_page_description: Tempeh or tempe is a traditional Indonesian soy product, that is made from fermented soybeans. It is made by a natural culturing and controlled fermentation process that binds soybeans into a cake form. Here a special fungus is used, which has the Latin name Rhizopus oligosporus, usually marketed under the name tempeh starter.
  It is especially popular on the island of Java, where it is a staple source of protein. Like tofu, tempeh is made from soybeans, but it is a whole soybean product with different nutritional characteristics and textural qualities. Tempeh's fermentation process and its retention of the whole bean give it a higher content of protein, dietary fiber, and vitamins. It has a firm texture and an earthy flavor, which becomes more pronounced as it ages.
context_section_description: Tempeh begins with whole soybeans, which are softened by soaking, and dehulled, then partly cooked. Specialty tempeh may be made from other types of beans, wheat, or may include a mixture of beans and whole grains.
  The principal step in making tempeh is the fermentation of soybeans which undergo inoculation with Rhizopus spp. molds, a type of filamentous fungus most widely used for the production of tempeh. A fermentation starter containing the spores of fungus Rhizopus oligosporus or Rhizopus oryzae is mixed in. The beans are spread into a thin layer and are allowed to ferment for 24 to 36 hours at a temperature around 30°C (86°F). The soybeans have to cool down to allow spore germination and abundant growth of mycelium. Later, the temperature of the beans will naturally rise and rapid mold growth happens for around 4 hours. As mold growth declines, the soybeans should be bound into a solid mass by the mycelium. In good tempeh, the beans are knitted together by a mat of white mycelium. Typically, tempeh is harvested after 48 hours of fermentation with its distinguishable whitish color, firm texture, and nutty flavor. Extended fermentation time results in an increase in pH and undesirable color darkening in the tempeh.
  During the fermentation process, optimal time of fermentation, temperature, oxygen, humidity, and pH levels are required to encourage the growth of the Rhizopus mold, while discouraging the growth of undesired microorganisms. The pH level should be kept around 3-5 by adding a mild acidulant such as vinegar, lactic acid, or acetic acid, thereby favoring mold growth and restricting the growth of spoilage microorganisms. Oxygen is required for Rhizopus spp. growth, but should be maintained at low levels to prevent the production of undesired microorganisms. Under conditions of lower temperature, or higher ventilation, gray or black patches of spores may form on the surface—this is not harmful, and should not affect the flavor or quality of the tempeh.  This sporulation is normal on fully mature tempeh. A mild ammonia smell may accompany good tempeh as it ferments, but it should not be overpowering.
  Traditional tempeh is often produced in Indonesia using Hibiscus tiliaceus leaves. The undersides of the leaves are covered in downy hairs (known technically as trichomes) to which the mold Rhizopus oligosporus can be found adhering in the wild. Soybeans are pressed into the leaf, and stored. Fermentation occurs resulting in tempeh. In particular, the tempeh undergoes salt-free aerobic fermentation.
caption: Making tempeh by wrapping boiled soybeans in banana leaves
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