Tempe (food)
Tempeh, also spelled tempe, is a traditional Indonesian fermented food produced by inoculating cooked soybeans with the mold Rhizopus oligosporus, which binds the beans into a firm, nutty-flavored cake that serves as a nutrient-dense, plant-based protein source.[1][2] Originating in Java, Indonesia, tempeh's history dates back at least to the 16th century, with the earliest documented reference appearing in the Serat Centini manuscript around 1815, though it likely emerged earlier through accidental fermentation of soybeans wrapped in leaves in the region's humid climate.[3] It quickly became a staple in Javanese cuisine, providing an affordable protein for the general population and evolving from a "food of the poor" to a culturally significant dish consumed across Indonesia, where annual production reached approximately 2.4 million tonnes as of 2019.[3][1] Tempeh is traditionally produced by soaking and dehulling soybeans, cooking them, inoculating with a Rhizopus starter culture, and incubating to allow mycelium growth that binds the beans. Wrapping in banana or hibiscus leaves facilitates the process, though modern production uses perforated plastic bags; variations may include other legumes or grains.[3][1][2] Tempeh provides about 20 grams of protein per 100 grams, along with fiber, essential amino acids, and minerals such as calcium, magnesium, and phosphorus. Fermentation reduces anti-nutritional factors like phytic acid, improving digestibility and nutrient bioavailability, including isoflavones; it is enriched with B vitamins and bioactive compounds like polyphenols for antioxidant activity, and may contain vitamin B12 from bacterial co-fermentation in some cases, though levels vary and are often low.[1][2] Studies suggest tempeh supports gut health through improved digestibility, may reduce cholesterol via isoflavones, enhance insulin sensitivity, and offer anti-inflammatory effects.[2] Once primarily local to Indonesia and Southeast Asia, tempeh has gained global popularity since the mid-20th century through Indonesian diaspora and plant-based diets, with commercial production now in Europe, North America, and beyond.[3]Etymology and History
Etymology
The word tempe derives from the Old Javanese term tumpi, referring to a white-colored food made from sago flour, likely due to the visual similarity with the white mycelium that forms during tempe's fermentation process.[4] This etymological root highlights the food's ancient ties to Javanese culinary traditions, where tumpi denoted a pressed or molded preparation.[3] The earliest known written reference to tempe appears in the Javanese manuscript Serat Centhini, composed around 1815, which describes a dish involving uncooked témpé alongside onions.[5] In European colonial records, the term first surfaced in 1875 within the Javaansch-Nederduitsch Handwoordenboek, a Javanese-Dutch dictionary by J.F.C. Gericke and T. Roorda, where it was spelled témpé and defined as a fermented soybean cake pressed into flat shapes for frying or baking.[5] Spelling conventions evolved with linguistic standardization; the accented témpé gave way to the modern Indonesian tempe in 1972 as part of orthographic reforms aligning with Malay influences.[5] In English adaptations, it became tempeh starting in 1950 to better convey the pronunciation and distinguish it from unrelated terms.[5] Originating as a Central Javanese term, tempe has remained consistent in naming across Indonesia, serving as the standard designation without notable variations, though its production and cultural significance extend to other regions like East Java and Yogyakarta.[3]Historical development
The earliest documented reference to tempeh appears in the Serat Centhini, a Javanese manuscript compiled around 1815 but depicting cultural and daily life from the 16th and 17th centuries during the reign of Sultan Agung of Mataram (1613–1645).[6] This text mentions tempeh (tempe) in the context of everyday Javanese cuisine, such as in dishes prepared with it, highlighting its established presence as a fermented soybean product.[6] In traditional Javanese agriculture, tempeh emerged as a vital protein source, utilizing locally cultivated soybeans inoculated with ragi (a natural fungal starter containing Rhizopus species), which allowed for efficient preservation and nutritional enhancement in resource-limited rural settings.[6] During the Dutch colonial era (17th–20th centuries), tempeh gained recognition among European observers in the Dutch East Indies, with the first European-language documentation in a 1875 Javanese-Dutch dictionary (Javaansch-Nederduitsch Handwoordenboek).[6] Scientific interest intensified in the late 19th century, as Dutch researchers like H.C. Prinsen Geerligs conducted pioneering studies on its fermentation process in 1895–1896, identifying the key mold Rhizopus oryzae.[6] Although commercial exports to Europe did not begin until the post-World War II period with Indonesian immigrants establishing production in the Netherlands around 1946, colonial-era publications and samples facilitated early knowledge transfer, including recipes documented in works like M.C. van der Burg's 1904 agricultural guide.[6] Following Indonesia's independence in 1945, tempeh production expanded rapidly as a cornerstone of national food security, with home-based industries proliferating across Java and beyond; by the 1970s, annual output reached tens of thousands of tons, supported by increasing soybean cultivation.[6] The establishment of the Indonesian Tempe Producers Association (KOPTI) in 1979 marked a key organizational milestone, growing to over 28,000 members by 1983 and fostering standardized practices amid rising domestic demand.[6] In the West, initial introductions occurred in the 1960s through academic research at institutions like Cornell University (e.g., Keith Steinkraus's studies starting in 1960) and the USDA's Northern Regional Research Laboratory, leading to the first U.S. commercial tempeh shop, Joy of Java, in 1961.[6] The 1970s saw broader popularization via counterculture communities, notably through Cynthia Bates at The Farm in Tennessee, who developed and distributed tempeh starters and educational materials like Beatnik Tempeh Making (1976), while figures associated with Stanford University, such as William Shurtleff, contributed to soyfoods advocacy and recipe dissemination.[6] In 2024, Indonesia submitted the culture of tempeh production for inscription on UNESCO's Representative List of the Intangible Cultural Heritage of Humanity, with evaluation ongoing as of November 2025.[7]Debate over origins
The origins of tempeh production remain a subject of scholarly debate, with arguments centering on whether the fermentation technique developed indigenously in Java or was influenced by external culinary traditions. Proponents of ancient Javanese origins point to evidence of soybean cultivation in Indonesia dating back to at least the 13th century CE, likely introduced earlier through maritime trade routes from mainland Asia, which would have enabled local experimentation with fermentation methods using native molds. Food historian Murdijati Gardjito of Gadjah Mada University has argued that tempeh was created by native Javanese people, emphasizing its use of whole soybeans bound by mycelium—a technique distinct from dehulled soy processing in Chinese or Indian traditions—and predating Hindu and Muslim arrivals on Java around the 8th to 15th centuries CE.[8] Counterarguments highlight the absence of documented references to tempeh before the 16th century, with the earliest confirmed mention appearing in the 1815 Javanese manuscript Serat Centhini, raising questions about its temporal depth. Some scholars suggest possible influences from Chinese traders, who introduced soybeans to Southeast Asia as early as the 7th century CE and produced similar mold-fermented soy products like koji, though these used different fungi such as Aspergillus rather than Rhizopus. Indian influences via spice trade routes are also proposed, given the exchange of legumes and fermentation knowledge between South Asia and Indonesia from the 1st millennium CE, but direct evidence linking these to tempeh remains speculative and unsupported by specific culinary records.[5][9] Recent genetic studies on Rhizopus strains used in tempeh fermentation bolster the case for indigenous Southeast Asian evolution. A 2021 analysis of 22 Rhizopus isolates from traditional Indonesian tempeh starters revealed high genetic diversity, including unique variants of Rhizopus oligosporus not found in commercial strains or non-Indonesian sources, indicating long-term local domestication rather than recent importation. Similarly, a 2022 ethno-microbiological review documented the adaptation of R. oligosporus strains to Indonesian environmental conditions and soy substrates over centuries, supporting their evolution within Java's microbial terroir independent of Asian mainland introductions. These findings, extending through 2025 with ongoing strain isolations from diverse Indonesian regions, underscore tempeh's roots in local innovation.[10][11]Production
Fermentation process
The production of tempe involves a solid-state fermentation process primarily driven by the mold Rhizopus oligosporus, transforming soybeans into a compact, mycelium-bound cake.[12] In the traditional method, high-quality yellow soybeans are selected and soaked in clean water for 12–24 hours at ambient temperature to hydrate the beans and promote natural acidification by indigenous lactic acid bacteria, which lowers the pH to around 4.5–5.0 and inhibits pathogenic growth.[13] The soaked soybeans are then dehulled manually by cracking and washing or using mechanical splitters to remove the outer hulls, ensuring uniform exposure for mold colonization.[14] Following dehulling, the beans are cooked by boiling for 30–60 minutes until tender, which kills vegetative bacteria, partially sterilizes the substrate, and facilitates the separation of any residual hull fragments.[13] The cooked beans are cooled to 28–32°C and inoculated with R. oligosporus spores, typically at a rate of 0.1–1% (w/w), sourced from commercial starters or previous tempe batches.[14] The inoculated mass is shaped into thin layers or cakes, traditionally wrapped in banana leaves or hibiscus leaves, and incubated to allow mycelial growth. Optimal fermentation conditions include a temperature of 30–37°C, relative humidity of 80–90%, and an incubation period of 24–48 hours, during which the mold's hyphae knit the beans together into a firm, white product while producing enzymes that break down proteins, lipids, and carbohydrates.[15] In industrial production, the process is scaled using automated dehullers, steam cookers, and climate-controlled incubators with microperforated polyethylene bags to regulate aeration and prevent over-drying, achieving consistent mycelial coverage without manual wrapping.[14] Lactic acid bacteria, such as Lactobacillus plantarum and Lactobacillus casei, coexist symbiotically with R. oligosporus during the initial soaking and early fermentation phases, generating organic acids that further acidify the substrate (pH 4.0–5.0) and suppress contaminants like Bacillus species or spoilage yeasts, thereby enhancing process stability and product safety.[13] This microbial interplay ensures selective dominance of the mold, with LAB populations peaking early before declining as fungal growth intensifies.[14]Yield and losses
In tempe production, significant dry matter losses occur during the initial soaking and cooking stages, primarily due to the leaching of water-soluble compounds such as oligosaccharides, proteins, and minerals into the processing water.[16] Typical losses range from 20-30% of the initial dry matter, with soaking alone accounting for up to 28% in some conditions, exacerbated by longer immersion times and smaller particle sizes that increase surface exposure.[16] These losses reduce the overall efficiency of the process but also contribute to improved digestibility by removing anti-nutritional factors.[17] The final yield of fresh tempe is influenced by these early losses as well as the subsequent fermentation, where the mold's mycelial growth binds the soybeans into a cohesive cake. From 1 kg of dry soybeans, producers typically obtain 1.5-2 kg of fresh tempe, depending on water absorption during cooking and the extent of mold binding.[18] This yield reflects a net retention of about 70-80% of the original dry matter after accounting for all stages, with fermentation itself causing minimal additional losses of 1-5% through microbial metabolism.[19] To minimize losses and optimize yield, producers can adjust cooking parameters, such as limiting boiling time to 30-60 minutes at 95°C, which reduces excessive leaching while ensuring proper dehulling and sterilization.[20] Additionally, selecting Rhizopus strains with strong mycelial binding properties, such as those exhibiting rapid growth and high lipolytic activity, enhances cohesion and nutrient retention during fermentation, potentially improving overall output by 10-15%.[21] These strategies are particularly important in industrial settings to balance efficiency and product quality.Quality assessment
Quality assessment of tempeh involves evaluating its sensory attributes, microbial composition, and physicochemical properties to ensure it meets standards for safety, texture, and flavor. These evaluations are critical to distinguish high-quality tempeh, characterized by proper Rhizopus fermentation, from defective products affected by over-fermentation or contamination. Standards such as those outlined in the Codex Alimentarius guide organoleptic and microbial criteria, emphasizing compact structure and absence of off-odors.[22] Sensory indicators provide initial visual and olfactory cues for tempeh quality. High-quality tempeh exhibits a firm, compact texture that holds together without easily disintegrating when cut, reflecting successful mycelial binding of the soybeans. It should have a nutty, earthy aroma reminiscent of mushrooms or meat, without pungent notes. The surface is covered uniformly with white mycelium from Rhizopus species, indicating healthy fermentation; the absence of irregular black spots or discoloration suggests no contamination by unwanted molds, though uniform gray-black sporulation from Rhizopus may occur in mature tempeh.[22] Microbial testing confirms the dominance of beneficial fungi and the absence of pathogens, ensuring food safety. Rhizopus species, such as R. oligosporus and R. microsporus, should predominate, typically comprising the majority of the fungal population in quality tempeh, as they drive the fermentation process and reduce antinutritional factors like aflatoxins. Testing involves plating techniques or molecular methods to verify low levels of contaminants; for instance, lactic acid bacteria may be present to inhibit pathogens, but absence of harmful bacteria like Bacillus cereus, Listeria monocytogenes, or Enterobacter cloacae is essential, with Enterobacteriaceae counts ideally below 10^5 CFU/g in hygienic production.[22][23] Instrumental methods quantify fermentation progress and detect defects like over-fermentation. Post-fermentation pH typically rises to around 7.0-7.5 due to ammonia production, a marker of complete Rhizopus activity; values outside this range may indicate incomplete or excessive fermentation. Ammonia levels are measured to assess over-fermentation, where elevated concentrations (leading to pungent odors) signal breakdown of proteins beyond optimal stages, compromising sensory quality. These measurements, often using pH meters or titration, complement sensory checks under controlled fermentation conditions.[24][25]Packaging
Tempe is traditionally packaged by wrapping the fermented cakes in banana leaves (Musa spp.) or hibiscus leaves (Hibiscus tiliaceus, locally known as waru leaves), which provide natural antimicrobial protection due to phenolic compounds and other bioactive substances that inhibit bacterial growth and extend freshness during local distribution.[26][27][28] These leaves not only maintain the product's moisture and shape but also impart subtle flavors while preventing contamination in ambient conditions typical of markets in Indonesia.[14] In modern production, vacuum-sealing removes oxygen to suppress aerobic mold growth and spoilage bacteria, thereby prolonging shelf life up to 14 days under refrigeration at 5°C without significant sensory degradation when the tempe is later fried.[29] Modified atmosphere packaging (MAP) further enhances preservation by replacing air with a gas mixture, such as 30% CO₂ and 70% N₂, which inhibits mold overgrowth and maintains texture and microbial stability during transport and retail storage.[29] Industrial packaging often employs microperforated plastic films, such as polyethylene, with small holes that permit controlled respiration and gas exchange to avoid anaerobic fermentation issues while barring external contaminants, aligning with food safety standards for scaled distribution.[30] These films mimic the breathability of traditional leaves, supporting tempe's short shelf life of about 5–7 days at ambient temperatures by balancing oxygen levels essential for product integrity.[30]Nutrition and Health
Nutritional composition
Tempeh, a fermented soybean product, offers a nutrient-dense profile that reflects its whole-bean composition and the effects of Rhizopus oligosporus fermentation. Per 100 grams of raw tempeh, it typically contains approximately 19 grams of protein, 11 grams of total fat (predominantly unsaturated), 8 grams of carbohydrates, and 6 grams of dietary fiber, contributing to about 192 calories. This macronutrient breakdown positions tempeh as a high-protein, low-carbohydrate food suitable for plant-based diets. In terms of micronutrients, tempeh is notably rich in several minerals essential for metabolic and bone health. It provides 2.7 milligrams of iron (15% of the daily value), 81 milligrams of magnesium (19% of the daily value), and 266 milligrams of phosphorus (21% of the daily value) per 100 grams. Additionally, tempeh is a source of bioactive compounds, including isoflavones such as genistein and daidzein, with total content ranging from 50 to 200 milligrams per 100 grams depending on production methods, and it contains small amounts of vitamin B12 (approximately 0.08–0.13 micrograms per 100 grams, though levels vary and may include inactive forms) synthesized by bacteria during fermentation.[31]| Nutrient | Amount per 100g | % Daily Value* |
|---|---|---|
| Protein | 19 g | 38% |
| Total Fat | 11 g | 14% |
| Carbohydrates | 8 g | 3% |
| Dietary Fiber | 6 g | 21% |
| Iron | 2.7 mg | 15% |
| Magnesium | 81 mg | 19% |
| Phosphorus | 266 mg | 21% |
| Vitamin B12 | 0.08–0.13 µg | 3–5% |
| Total Isoflavones | 50–200 mg | N/A |