Tempeh
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.
Etymology
The etymology of the term tempe itself is suggested to be derived from Old Javanese tumpi, a whitish food made from fried batter made from sago or rice flour which resembles rempeyek. Historian Denys Lombard suggests however that it is linked to the local term tape or tapai which means "fermentation".History
Tempeh originated in Indonesia, almost certainly in Java, more precisely central or east Java, with an estimated discovery between a few centuries ago to a thousand years or more. Around the 12th to 13th century, a type of food was mentioned as kadêlê in an old Javanese manuscript, Serat Sri Tanjung. However, it is not clear whether kadêlê refer to processed fermented soy or not, since the term in Javanese today refer to "soybeans". The earliest known reference to it as têmpê appeared in 1815 in the Serat Centhini.The invention of tempeh is connected to tofu production in Java. The tofu-making industry was introduced to Java by Chinese immigrants circa the 17th century. Chinese Indonesian historian Ong Hok Ham suggests that tempeh was accidentally produced as the by-product of the tofu industry in Java; as discarded soybeans caught the spores of a whitish fungus that was found to be edible. Three detailed, fully documented histories of tempeh, worldwide, have been written, all by Shurtleff and Aoyagi.
Production
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. 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 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.
Determining quality
Once tempeh is produced, it is divided into three categories based on its quality: good, unfinished, and inedible. Good tempeh includes beans that are bound into a firm, compact cake by a dense, uniform, white mycelium, which should permeate the entire cake; the beans should be barely visible. The odor of good tempeh should be pleasant, clean, subtly sweet or resemble the aroma of mushrooms. The entire tempeh should lift as a single, cohesive cake without crumbling when shaken gently. Unfinished tempeh has beans that are bound together loosely by a sparse white mycelium, hence it crumbles easily. Unfinished tempeh should be incubated longer unless it has been incubated more than 8 hours past the recommended time. If it has been incubated for enough time and still remains unfinished, it should be discarded. Inedible tempeh has beans with foul odor, resembling strong ammonia or alcohol, indicating the development of undesirable bacteria due to excess moisture or overheating. Inedible tempeh cake is wet, slimy, and mushy with a collapsed structure. Its color is tan to brown and mold develops in sparse patches.Packaging
Food grade wrapping paper and perforated polyethylene bags are the most suitable materials for packaging tempeh. They have demonstrated good retention of the quality of tempeh and extension of the shelf life of tempeh for three days compared to fresh tempeh. Appropriate packaging is important as it provides optimum oxygen supply and temperature for inoculation and fermentation to occur during processing. Tempeh is a perishable food and must be wrapped and placed into the refrigerator or freezer immediately after incubation or other processing steps such as blanching. In the refrigerator or freezer, stacking of tempeh should be minimized to prevent overheating and the undesirable, gradual continuation of fermentation, both of which shorten the storage life of tempeh. Even under cold temperature, tempeh continues to respire and undergo slow decomposition from microorganisms and its natural enzymes. Therefore, tempeh should be well cooled for at least two to five hours in a cooler before they undergo further packaging. Tempeh packaged in perforated polyethylene bags is usually repacked inside another labeled, non-perforated bag for distribution and sale, and for easier labeling. If the tempeh is only packaged in one perforated bag, the label must be directly attached to the perforated surface with the use of government food contact approved adhesive. They are then bulk packed in cartons and returned to the refrigerator or freezer to await shipment.Nutrition
The soy carbohydrates in tempeh become more digestible as a result of the fermentation process. In particular, the oligosaccharides associated with gas and indigestion are greatly reduced by the Rhizopus culture. In traditional tempeh-making shops, the starter culture often contains beneficial bacteria that produce vitamins such as B12. In western countries, it is more common to use a pure culture containing only Rhizopus oligosporus, which makes very little B12 and could be missing Citrobacter freundii and Klebsiella pneumoniae, which have been shown to produce significant levels of B12 analogs in tempeh when present. Whether these analogs are true, bioavailable B12 has not been thoroughly studied yet.The fermentation process also reduces the phytic acid in soy, which in turn allows the body to absorb the minerals that soy provides.
Preparation
In the kitchen, tempeh is often simply prepared by cutting it into pieces, soaking in brine or salty sauce, and then fried. In Java, tempeh is often traditionally prepared by cutting it into pieces, marinated in a mixture of ground garlic, coriander and turmeric, salt and water; then deep fried, and often served with sambal ulek chili paste. Cooked tempeh can be eaten alone, or used in chili, stir fries, soups, salads, sandwiches, and stews. Tempeh's complex flavor has been described as nutty, meaty, and mushroom-like. It freezes well, and is now commonly available in many western supermarkets, as well as in ethnic markets and health food stores. Tempeh can be steamed, marinated, thinly sliced, blackened, or crumbled into sauces and stews.Tempeh performs well in a cheese grater, after which it may be used in the place of ground beef. When thin-sliced and deep-fried in oil, tempeh obtains a crisp golden crust while maintaining a soft interior. Its sponge-like consistency makes it suitable for marinating. Dried tempeh is more portable and less perishable and may be used as a stew base. Sometimes when tempeh is diced and left, they will create white feathery fluff which bonds the cut—this is the Rhizopus mold still growing—this is normal and perfectly edible.
Types
The most common tempeh is made from fermented soybeans. However, traditionally other ingredients such as ampas tahu, ampas kelapa and peanuts may be used in a fashion similar to the tempeh making process, although perhaps using different fungi or attracting other microbes.''Tempeh kedelai''
Also called tempeh kedele or tempeh dele, or simply just tempeh. The most common and widely known tempeh, made from controlled fermentation of soybeans.''Tempeh gembus''
Soft and fluffy tempeh made from soy pulp or tofu dregs. Tempeh gembus usually can be found in traditional markets of Java, at a price lower than that of common soybean tempeh. It is made into a variety of dishes; for example it can be battered and/or fried, used in sayur lodeh, or tempeh bacem. Tempeh gembus is known by different names across Java; for example as tahu cokol or tahu susur in Temanggung.''Oncom''
Tempeh oncom, or simply onchom, is made from peanut press cake or soy dregs. Among fermented bean products, oncom is more prevalent in West Java, where it serves as the main ingredient in various Sundanese cuisine traditional dishes, including oncom goreng, oncom leunca, and nasi tutug oncom. There are two types of oncom: a bright red-orange kind with Neurospora sitophila, and a black one with the same fungi as tempeh uses.''Tempeh menjes kacang''
A specialty of Malang, the rough textured tempeh menjes kacang is made from black soybeans mixed with other ingredients, such as peanut dregs, cassava fiber, and soybean meal. The process of making menjes kacang is quite similar to black oncom.''Tempe bongkrèk''
Tempeh bongkrèk is a variety of tempeh from Central Java, notably Banyumas regency, that is prepared with coconut dregs. This type of tempeh has led to several cases of fatal food poisoning, as it occasionally gets contaminated with the bacterium Burkholderia gladioli, and the unwanted organism produces toxins from the coconut, besides killing off the Rhizopus fungus due to the antibiotic activity of bongkrek acid.Fatalities from contaminated tempeh bongkrèk were once common in the area where it was produced. Thus, its sale is now prohibited by law; clandestine manufacture continues, however, due to the popular flavor. The problem of contamination is not encountered with bean and grain tempeh, which have a different composition of fatty acids that is not favorable for the growth of B. gladioli, but encourages growth of Rhizopus instead. When bean or grain tempeh has the proper color, texture and smell, it is a very strong indication the product is safe. Yellow tempeh bongkrèk is always highly toxic due to toxoflavin, but tempeh bongkrèk with a normal coloration may still contain lethal amounts of bongkrek acid.
Oat tempeh
A new form of tempeh based on barley and oats instead of soy was developed by scientists at the Swedish Department of Food Science in 2008. It can be produced in climatic regions where it is not possible to grow soybeans.Process
Sometimes tempeh is left to ferment further, creating a pungently stronger "almost rotten" tempeh called tempeh semangit in Javanese.The wrappings used in tempeh making can contribute to its flavor and aroma. Though some prefer the traditional banana, waru or teak leaf, readily available plastic sheet wrappings have been increasingly widely used.
Common tempeh
Common soybean tempeh that has undergone sufficient fermentation process.''Tempeh semangit''
In Indonesia, ripe tempeh is considered a delicacy. Names include tempeh semangit in Java, hampir busuk tempeh or tempeh kemarin. Having a slightly pungent aroma, small amounts are used as a flavoring agent in traditional Javanese sayur lodeh vegetable stew and nasi tumpang.''Tempeh gódhóng''
In Javanese language, the term gódhóng means "leaf". Traditionally tempeh is wrapped in organic banana leaf, daun waru or daun jati.''Tempeh murni''
Pure soybean cake, tempeh made in plastic wrap without any fillings or additives such as grated raw papaya. This was meant to create a more "hygienic and pure" tempeh free from any impurities or unwanted microbes.Cooking methods and recipes
The simplest way to cook tempeh is by frying. It is both deep-fried and stir-fried. However, there are several cooking methods and recipe variations. Among others are:''Tempeh goreng''
Probably the simplest and most popular way to prepare tempeh in Indonesia. The tempeh is sliced and seasoned in a mixture of ground garlic, coriander seeds and salt, and then deep fried in palm oil. The tempe might be coated in batter prior to frying, or directly fried without any batter.''Tempeh bacem''
Tempeh bacem is a traditional Javanese dish originating in Central Java. Bacem is a Javanese cooking method of braising in spices and palm sugar. The tempeh is first braised in a mixture of coconut water, palm sugar, and spices including coriander seeds, shallots, galangal, and bay leaves, and then briefly deep-fried. The result is a moist, sweet and spicy, dark-colored tempeh. Tofu may also be used, yielding tahu bacem.''Tempeh mendoan''
This variation is often found in Purwokerto. The word mendoan originates in the Banyumas regional dialect, and means "flash-fried". The tempeh is first dipped in spiced flour before quickly frying in very hot oil, resulting in a product that is cooked on the outside, but raw or only partially so on the inside. It has a limp, soft texture compared to the more common, crisp, fully fried tempeh.''Tempeh kering''
Also known as kering tempeh, or sambal goreng tempeh if mixed with plenty of hot and spicy sambal chili pepper sauce. It is a crispy, sweet and spicy, fried tempeh. The raw tempeh is cut into small sticks and thoroughly deep-fried until no longer moist, and then mixed with palm sugar, chili pepper or other spices, or with sweet soy sauce. Often it is mixed with separately fried peanuts and anchovies. This dry tempeh will keep for up to a month if cooked and stored properly.''Tempeh orek'' or ''orak-arik tempeh''
This variation is almost identical to tempeh kering, but is more soft and moist. The sweet taste is due to generous addition of kecap manis.''Tumis tempeh'' or ''oseng tempeh''
tempeh with vegetables such as green bean, basil, or onion, with spices. Other recipes might add coconut milk for a milky-colored, and rather moist, stir-fried tempeh.''Tempeh penyet''
Fried tempeh mixed with sambal chili paste in a mortar and pestle. Usually served in addition to other penyet dishes, such as ayam penyet or iga penyet.''Tempeh satay''
Tempeh skewered and grilled as satay.Sate kere from Solo in Central Java is made from fluffy tempeh gembus. Ground tempeh can also be made into a thick sauce, such as in sate ambal, a chicken satay from Kebumen, Central Java where tempeh flavored with chili and spices replaces the more common peanut sauce.
''Kripik tempeh''
Kripik tempeh snack crackers; a thinly sliced tempeh, battered and deep fried until crispy. It is popular across Java, but notably produced in Bandung, West Java.Grilled tempeh
Grilled tempeh over charcoal or fire.Tempeh sandwich or tempeh burger
Fried, grilled or otherwise cooked tempeh patties, sandwiched between slices of bread or hamburger buns with salad, sauces or seasonings.Preservation
Freshly made, raw tempeh remains edible for a few days at room temperature. It is neither acidic nor does it contain significant amounts of alcohol. It, however, does possess stronger resistance to lipid peroxidation than unfermented soybeans due to its antioxidant contents.Cooked as tempeh kering, the deep fried and seasoned bits of tempeh can last for a month or more and still be good to consume, if cooked correctly and stored properly in air-tight jar. The deep frying process removes the moisture, preventing further fermentation and deterioration, thus prolonging its shelf life.