Tempeh

• 1. Introduction

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  Tempeh is a cake of soybeans held together by living white threads. A good one lifts from the table as a single piece, with no crumbs falling away. The threads are the mycelium of a fungus, which knits the beans into a solid mass over about two days. This traditional Indonesian food was born on the island of Java, where it is a staple source of protein. Unlike tofu, it is made from the whole bean. Its flavor is earthy and grows stronger as it ages. How did a fungus find its way onto stored soybeans, and who first realized the result was good to eat? Why do historians still argue about whether tofu came first? What separates a perfect cake from a ruined one? And why can one humble variety, made from coconut instead of beans, kill?

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• 2. Name and Spelling

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  The Old Javanese word tumpi names a whitish food of fried batter, made from sago or rice flour, that resembles the cracker called rempeyek. The word tempe is thought to descend from it. The historian Denys Lombard offers a second possibility. He suggests a link to the later words tape or tapai, which mean fermentation. In the Western world, writers prefer the spelling tempeh, so readers know the final e is pronounced. The first known use of that spelling appears in a German article from 1896. Other forms, such as témpé, also circulated for decades. Since the 1960s, tempeh has been the standard spelling in English. The word traveled easily, but the food itself stayed unfamiliar far from its homeland for a very long time.

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• 3. Disputed Origins

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  Bayat, in Klaten, Central Java, is where the historical evidence says tempeh was first made. By around 1700 it was in common use. The invention seems to have been an accident. A fungus reached stored soybeans, probably from the teakwood and sea hibiscus leaves that Javanese people have long used to wrap food. Traditional makers still rely on an usar, a leaf full of mycelium, instead of store-bought starter. The first beans used were black soybeans, a native plant.

  Murdijati Gardjito, a food historian at Gadjah Mada University, argues that native Javanese people made tempeh before Chinese-style tofu arrived. Old texts mention tempe dhele, Old Javanese for native soybean tempeh, and dhele named the native variety. The white soybeans used for most tempe dhele today were once called dhele putih. They reached Java only centuries later. Mary Astuti, another food historian at the same university, agrees that the native bean grew in Java before the Chinese arrived. Sri Tandjung noted that Javanese people were eating cooked native black soybeans by the 12th century. The Serat Centhini shows that cooks had mastered tempeh by the 16th or 19th century, depending on the period the writer meant. They no longer ate it plain. They turned it into many dishes. Gardjito also explains why nobles rarely wrote about it. It was never royal cuisine. It was a staple of the lower classes.

  A rival theory points to tofu, which Indonesians call tahu. The historian Ong Hok Ham suggests tempeh began as a byproduct of tahu, since both come from soybeans and soybeans originated in China. Food journalist Andreas Maryoto agreed. In 17th-century Java, he said, discarded soybeans may have caught the spores of an edible whitish fungus. In 2025, Zaelani named this the Okara-Tempe Hypothesis. It proposes that tempeh began with okara, the residue of tofu, which fermented naturally before cooks adapted the method to whole soybeans.

  There is a problem with that story. Tahu is made from white soybeans, Glycine max, native to Japan and China. The earliest tempe dhele used native black soybeans, Glycine soja. Tahu reached Kediri in the 13th century and was eaten by the Mongolians who arrived in Java. For a long time only the rich could afford it, because its production was complex and its white soybeans were imported. Around the 17th or 19th century it became available to everyone. As tahu became the common person's food, tempeh makers also switched to white soybeans. Other commodity crops replaced the black bean. The original tempe dhele has been forgotten, and dependence on imported white soybeans keeps growing.

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• 4. The Fermentation Craft

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  Between 24 and 36 hours at about 30 degrees Celsius, or 86 Fahrenheit, is the window in which tempeh takes shape. The work begins with whole soybeans, which are softened by soaking, dehulled, and partly cooked. Some makers add vinegar to the soaking water, which changes the sensory character of the final product. A starter holding spores of the fungus Rhizopus oligosporus or Rhizopus oryzae is then mixed in. The beans are spread in a thin layer. They must first cool so the spores can germinate and the mycelium can spread. Then the temperature of the beans rises on its own, and rapid mold growth runs for about 4 hours. As growth slows, the mycelium should bind the beans into one mass. Most tempeh is harvested after 48 hours, white, firm, and nutty. Longer fermentation raises the pH and darkens the color.

  The maker is managing a small ecosystem. The pH should sit around 3-5, which a mild acid such as vinegar, lactic acid, or acetic acid can achieve. That favors the mold and holds back spoilage microbes. The mold needs oxygen, but only a little, because too much invites unwanted organisms. In cooler or better-ventilated conditions, gray or black patches of spores may appear on the surface. They are harmless and normal on fully mature tempeh. A mild ammonia smell is acceptable if it is not overpowering.

  Traditional Indonesian makers often press the beans into leaves of Hibiscus tiliaceus. The undersides of those leaves are covered in downy hairs, called trichomes, where the mold Rhizopus oligosporus clings in the wild. Fermentation there is aerobic and uses no salt. Traditional inoculation also admits other species, including Rhizopus arrhizus and Rhizopus delemar. These can outcompete the main mold and give a white, woolly look and a more pleasant aroma. In the 1960s, such variants were famous in Malang and Purwokerto. Malang sits on a cool plateau. There, Rhizopus oligosporus produced a loose cake that smelled of alcohol, while Rhizopus arrhizus, which prefers lower temperatures, worked better. Commercial starter has since made Rhizopus oligosporus the only mold in most tempeh on Java.

  Quality falls into three grades. Good tempeh has a dense, uniform white mycelium running through the whole cake, so the beans are barely visible. Its smell is clean, subtly sweet, or like mushrooms. Unfinished tempeh is bound by sparse mycelium and crumbles easily. It should incubate longer, unless it has already passed the recommended time by more than eight hours. In that case it should be thrown away. Inedible tempeh smells strongly of ammonia or alcohol, a sign of unwanted bacteria from excess moisture or overheating. It is wet, slimy, and mushy, tan to brown, with sparse patches of mold.

  The process also costs material. Hulls make up about 8% of the dry beans, and soaking, washing, and cooking leach away another 12-17%. Losses during fermentation range from 2.1 to 10%. In practical terms, 100 g of dry soybeans yields about 170 to 210 g of fresh tempeh.

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• 5. Nutrition and Microbes

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  A 100 g serving of tempeh supplies 192 calories. By weight it is 60% water, 20% protein, 8% carbohydrates, and 11% fats. It is a rich source of several B vitamins and minerals, with riboflavin at 30% of the Daily Value and manganese at 62%. Fermentation changes how the body handles the beans. The soy carbohydrates become more digestible. The Rhizopus culture greatly reduces the oligosaccharides associated with flatulence and indigestion.

  Vitamin B12 is a more complicated story. In traditional tempeh shops, the starter culture often includes bacteria that make B12, though it is uncertain whether that B12 is always present or usable by the body. Western producers more often use a pure culture of Rhizopus oligosporus alone. That mold makes little B12. A pure culture may also lack Citrobacter freundii and Klebsiella pneumoniae, two bacteria shown to produce significant levels of B12 analogs in tempeh. Studies on fortifying tempeh with B12 through fermentation point to lactic acid bacteria and propionic acid bacteria as producers.

  The mold also defends its own cake. Rhizopus cultures make natural, heat-stable antimicrobial agents against spoilage and disease-causing microbes. The mold can inhibit the fungi Aspergillus flavus and Aspergillus parasiticus by interfering with the buildup of aflatoxin B1, the mycotoxin of greatest concern. Rhizopus oligosporus is also reported to make four to five antibacterial substances during fermentation. Phenolic compounds act against Helicobacter pylori. An antibacterial protein works against Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, and Streptococcus cremoris.

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• 6. Beyond Soybeans

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  Tempe kedele, also called tempe dele, is the best-known tempeh, yet Javanese makers have applied the method to many other materials. Okara, coconut dregs, and peanuts have all been used. Some of these attract different fungi or other microbes, such as kara benguk and kara pedhang, which can be toxic if not prepared correctly. Traditional Javanese custom treats wasting food as disrespect to Nature and other beings, which encourages cooks to use every part of an ingredient. Oncom, a related product, is made from peanut press cake or soy dregs and is prevalent in the Sundanese culture of West Java. It comes in two types. One is bright red-orange and uses Neurospora sitophila. The other is black and uses the same fungi as tempeh.

  Tempe gembus is soft and fluffy tempeh made from soy pulp, or tofu dregs. It sells in the traditional markets of Java at a lower price than ordinary tempeh. It goes into sayur lodeh and tempe bacem, or it is battered and fried. In Temanggung it is called tahu cokol or tahu susur. Tempe menjes kacang, a specialty of Malang, is rough-textured. It combines black soybeans with peanut dregs, cassava fiber, and soybean meal.

  Age creates another set of names. Tempe mondhol is not fully fermented, so the mycelium has not covered the whole surface, and the taste of the beans is more solid and profound. Tempe wayu is day-old tempeh just starting to age. Tempe semangit, a few days old, turns yellowish and a bit slimy, with a stronger smell. Tempe bosok has blackened mycelium and a putrid smell. In Indonesia, ripe tempeh of two or more days is considered a delicacy. It goes by names including tempe semangit, meaning stinky tempeh, hampir busuk, meaning almost rotten, and tempe kemarin, meaning yesterday tempeh. Small amounts flavor the Javanese vegetable stew sayur lodeh and the sauce sambal tumpang.

  The wrapping matters too. Tempe gódhóng takes its name from the Javanese word for leaf, and traditional wrappers are banana, waru, or teak leaves. They add flavor and aroma, though plastic sheeting is increasingly common. Tempe murni is pure soybean cake in plastic wrap, without fillings such as grated raw papaya, and was meant to be more hygienic. In 2008, scientists at the Swedish Department of Food Science developed a tempeh from barley and oats. It can be produced in climates where soybeans will not grow.

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• 7. The Bongkrek Poison

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  In Banyumas, in Central Java, a tempeh made from coconut dregs has killed people for generations. Tempe bongkrèk was cheap, so it served as a main source of protein. Occasionally it became contaminated with the bacterium Burkholderia gladioli. That organism makes two toxins, bongkrek acid and toxoflavin, from the coconut. It also kills off the Rhizopus fungus, because bongkrek acid has antibiotic activity.

  Dutch researchers recorded an outbreak in 1895 but did not pursue the cause. In the early 1930s, W. K. Mertens and A. G. van Veen of the Eijkman Institute in Jakarta took up the question. During that decade, an economic depression pushed some people to make tempe bongkrek at home instead of buying it from trained producers. Poisonings then reached 10 to 12 a year. The researchers identified a bacterium called Pseudomonas marginata, now also named Burkholderia cocovenenans, as the source of the poison. It is commonly found in plants and soil. Coconuts and corn can take it up, and bongkrek acid then forms during their fermentation.

  The toll continued long after. Since 1975, contaminated tempe bongkrek has caused more than 3000 cases of poisoning. The reported death rate in Indonesia is 60%. The government banned production in 1988, yet secret manufacture continues because people love the flavor.

  Bean and grain tempeh do not share the danger. Their fatty acids are different, and they do not favor the bacterium. They encourage Rhizopus instead. When such tempeh has the proper color, texture, and smell, it is a very strong sign that it is safe. Coconut tempeh gives no such assurance. Yellow tempe bongkrèk is always highly toxic because of toxoflavin. Even a normal-looking cake may hold a lethal amount of bongkrek acid.

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• 8. Kitchen and Shelf

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  Garlic, coriander seeds, and salt, ground together, are the seasoning behind tempe goreng, perhaps the simplest and most popular tempeh dish in Indonesia. The slices are deep-fried in palm oil, with or without batter, until golden brown. Tempe bacem is a Central Javanese dish in which the tempeh is braised in coconut water, palm sugar, coriander seeds, shallots, galangal, and bay leaves, then briefly fried. Tempe mendoan comes from Purwokerto. Its name, from the Banyumas dialect, means flash-fried. The slices are dipped in spiced flour and fried in very hot oil, leaving the inside raw or partly raw and the texture limp and soft.

  Tempe kering is cut into small sticks and fried until dry, then tossed with palm sugar, chili, or sweet soy sauce. Cooks often add fried peanuts and anchovies. Stored properly in an airtight jar, it keeps for a month or more, because frying removes the moisture that fermentation needs. Tempe orek is a softer, moister cousin made with generous kecap manis. Tempe penyet is fried tempeh crushed with sambal in a mortar, served beside ayam penyet or iga penyet. Sate kere, from Solo, is the poor man's satay, made from tempe gembus. In Kebumen, sate ambal replaces the usual peanut sauce with a sauce of ground tempeh flavored with chili. Kripik tempe, thin-sliced and fried crackers, is notably produced in Bandung and Malang.

  Cooks in the West treat tempeh as a flexible ingredient. Grated, it can stand in for ground beef in tacos. Thin-sliced and deep-fried, it gains a crisp golden crust and keeps a soft interior. Its sponge-like texture takes a marinade well. Its flavor is described as nutty, meaty, and mushroom-like. If diced tempeh sprouts white feathery fluff, that is simply the mold still growing, and it is perfectly edible.

  Freshly made tempeh stays edible for a few days at room temperature, and it is sold within 48 hours of leaving the incubator. In the fridge, below 40 Fahrenheit, it keeps three to five days and sometimes a week. Steaming or parboiling beforehand stretches that to two or three weeks. Freezing is the preferred method, and it preserves tempeh for months with only a small loss of texture and flavor. Drying offers alternatives. Hot-air drying at 200 Fahrenheit for 90 to 120 minutes reduces moisture to 2-4% and gives a shelf life of several months. Sun drying is the cheapest, though sunlight can destroy some of the B12. Freeze-drying is the most expensive and best at keeping nutrients. Deep-fried tempeh, sealed in bags, lasts around a week.

  Tempeh long stayed unprominent far from Java. Then, in the United Kingdom in 2025, it was reported to have suddenly taken off. Annual sales of one brand rose by 736%, and another by 128%. In North America, the tempeh market is expected to grow at a compound rate of 6.1% from 2024 to 2030, reaching $1519.8 million.

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