Bekang / Bekang-um

What it is

Bekang, also called bekang-um, is a traditional fermented soybean food of the Mizo communities of Mizoram in northeastern India. Whole soybeans are cooked until soft and allowed to ferment naturally in a warm, moist environment. Traditional methods use leaves, bamboo containers and the warmth of a household fireplace; some also include a sprinkling of wood ash. The resulting beans become sticky, soften further and acquire a strong fermented aroma. Bekang is eaten as a side dish or used in small quantities to season other foods.

The name bekang-um is recorded directly in research on Mizo food-processing traditions. The language is written in the Latin alphabet, so the original name does not require a separate indigenous script. In regional scientific literature, bekang and bekang-um generally refer to the same fermented soybean tradition. The suffix -um also occurs in names of other Mizo fermented foods, but this does not imply that those foods use the same organisms or preparation conditions.

Bekang belongs to the family of alkaline bacterial soybean fermentations, together with kinema, tungrymbai, hawaijar and axone. Bacillus subtilis is a prominent organism, but the naturally fermented product contains a broader microbial community. It is not a mould-fermented food like tempeh. Nor is it simply a local name for Japanese natto. Bekang has its own traditional wrapping materials, handling methods, ash practices, microbial composition and culinary uses.

A 2015 study examined forty-three bekang samples and recovered 217 Bacillus isolates. Bacillus subtilis accounted for 51.8% of those isolates, with B. licheniformis, B. pumilus and several other species also identified. These proportions describe cultured isolates, not a complete census of the organisms in the beans. Later DNA-sequencing investigations found substantial populations of other genera, demonstrating that the microbiology cannot be described accurately as a pure B. subtilis fermentation.

The primary edible ingredient is soybean, Glycine max, usually a small-seeded variety in traditional descriptions. Leaves of Callicarpa arborea or Phrynium species are used to wrap the beans or line fermentation baskets. Fresh bekang is typically sticky, moist and pungent. Some producers dry it after fermentation to make it easier to store and use later. The fermented beans can be eaten directly with seasonings or incorporated into cooked dishes, including vegetable preparations and curries served with rice.

History

Bekang is part of the inherited food knowledge of Mizo communities in Mizoram, where fermented foods traditionally have an important place alongside rice, vegetables and meat. The method is associated with household preparation, local plants, cooking fires and techniques passed between generations. Research on northeastern Indian soybean ferments emphasises the role of women in producing and selling these foods. This establishes bekang as a local food tradition, but does not identify the century in which it began.

The earliest securely dated, product-specific scientific documentation identified here is the 2009 paper by Jyoti Prakash Tamang, Rajen Chettri and Rudra Mani Sharma on indigenous women's knowledge of fermented soybean foods. It describes the preparation of bekang by Mizo women, including soaking, boiling, leaf wrapping and warm fermentation. The paper also documents its sale in local markets. Its observations establish a working tradition at the time of publication, not an origin date.

In 2015, researchers at Pachhunga University College and Mizoram University published Traditional Food Processing Techniques of the Mizo People of North East India. They collected information through interviews and surveys of local residents, documenting several fermented and preserved foods. Their account describes bekang-um as beans placed on hnahkiah leaves over a traditional chhihri sieve, sprinkled with fireplace ash and kept covered near the fire for three days. It also records less familiar uses, including drying and adding fried, ground beans to tea in some places.

The same year, Chettri and Tamang published a detailed investigation of Bacillus species from bekang and tungrymbai. In 2019, researchers in Mizoram compared a traditional sunlight-based fermentation with a controlled wooden incubator. In 2021, another research group used high-throughput DNA sequencing to investigate the bacterial communities present in bekang collected from Aizawl markets. A 2023 study compared its microbial and chemical composition with fermented soybean foods from Manipur and Nagaland.

Modern research also documents risks associated with inadequate hygiene. An outbreak in Chite, Aizawl, investigated in 2020 and reported in 2023, was associated with locally purchased bekang-um and Salmonella infections. A separate outbreak in Keifang in September 2024, reported in April 2026, linked contaminated fermented soybeans to atypical enteropathogenic Escherichia coli. These investigations belong to the modern history of production and food-safety oversight, not to the origin of the food.

Claims that bekang was invented thousands of years ago, came directly from Japan or has always used one Bacillus strain have no support. Its traditional history is documented through ethnography and contemporary practice; its precise early chronology remains unknown.

How it works: bacteria, enzymes and chemistry

Bekang is primarily an alkaline bacterial fermentation of cooked soybeans. Soybeans contain abundant storage proteins, especially glycinin and beta-conglycinin, alongside oil and smaller quantities of carbohydrates. Cooking softens the beans and changes the structure of their proteins. During fermentation, Bacillus bacteria can release extracellular proteases that break the large proteins into peptides and amino acids. These smaller compounds contribute to savoury taste and provide substrates for further microbial metabolism.

The 2015 culture-based investigation found Bacillus subtilis to be the most frequently isolated Bacillus species in bekang, representing 51.8% of the 217 isolates. Bacillus licheniformis accounted for 16.5% and B. pumilus for 9.1%. Additional species included B. circulans, B. coagulans and others. The researchers measured an average Bacillus population of approximately 8.2 log colony-forming units per gram across the investigated fermented soybean products. The species percentages apply to cultured isolates, not to the proportions of microbial DNA or active cells in every batch.

A separate 2021 sequencing study found a more complicated community. Its third-day bekang sample contained 52.36% Staphylococcus and 38.47% Bacillus among the assigned bacterial sequences. By the seventh day, Staphylococcus had declined to 17.90%, while Bacillus remained close to 38%. The two results do not conflict: culture-based isolation and DNA sequencing measure different aspects of the community. The fermentation is therefore not exclusively Bacillus-led at every stage.

Proteolysis contributes to alkalinity because further amino-acid metabolism can release ammonia and other nitrogenous products. A 2019 experiment measured increasing protease activity, free amino acids and pH during fermentation. In the controlled-temperature samples, the reported pH increased from 5.25 at the start to 8.47 after four days. The 2021 market-sample study reported a pH of approximately 7.93. These are measurements from different experimental settings, not a universal target pH or an indication of safe completion.

Bacillus strains may also produce extracellular poly-gamma-glutamic acid, a polymer associated with the stringy texture of natto-like foods. A 2014 investigation reported that a bekang-derived B. subtilis strain, BT:B9, produced 2.8 mg/mL of this polymer under laboratory conditions. The same value cannot be assigned to finished village bekang. Alpha-amylase activity has also been measured, although soybeans contain much less starch than cereals. A 2019 study found that reducing sugars initially increased and then declined as fermentation continued.

A 2023 comparative study used bacterial profiling and gas chromatography–mass spectrometry to examine bekang, hawaijar and akhone. Bekang showed a comparatively greater representation of certain short-chain fatty acids among detected metabolites. Correlations between bacterial groups and metabolites suggest possible metabolic relationships, but do not prove which organisms directly produced each compound. The complete flavour depends on the beans, local microbial community, ash or leaf handling where used, fermentation temperature and time.

How it is made and why each step matters

Traditional bekang preparation begins with small, dried soybeans. A 2009 ethnographic study describes soaking the cleaned beans for approximately 10–12 hours, then boiling them for one to two hours until cooked. The beans are drained to remove excess water. A 2015 review gives a different cooking duration of two to three hours. Both descriptions involve thoroughly softened soybeans, but their cooking times differ and are not interchangeable.

The cooked beans are placed in a bamboo basket or tray lined with locally used leaves. A 2009 account identifies Callicarpa arborea, called nuhlhan in that publication, and Phrynium species, called hnahthial, as traditional wrapping materials. The leaves help hold the cooked beans together and separate them from the container. They may also carry microorganisms that contribute to spontaneous fermentation, but the species and strains introduced by particular leaves have not been established through controlled comparisons.

Wood ash is included in some traditional methods. The 2015 field account by Lalthanpuii and colleagues describes spreading cooked soybeans on hnahkiah leaves over a chhihri sieve, sprinkling ash from the fireplace and covering the beans with more leaves. A 2015 microbiological study also describes adding a small amount of firewood ash before fermentation. Ash contains alkaline mineral compounds and may affect the pH of the bean surface. The resulting chemical conditions are not quantified, and ash is not shown to be indispensable in every bekang method.

The wrapped beans are covered with cloth and kept near a fireplace or earthen oven. Published descriptions give fermentation periods of three to four days, with reported ambient conditions varying between approximately 20–35°C and 25–40°C. A separate Mizo field account describes leaving the covered beans undisturbed for three days over the fireplace, sometimes using a sunny location instead. The traditional process does not use a measured inoculum of B. subtilis or a laboratory-controlled temperature.

A 2019 experiment used a different preparation to investigate temperature control. Researchers washed and soaked 1 kg of locally obtained soybeans overnight, then autoclaved them at 121°C for one hour. They divided the beans into two groups, placed them on trays lined with hnahkiah leaves and sprinkled them with clean firewood ash. One group fermented in a wooden incubator maintained at approximately 35°C, while the other was kept under sunlight with uncontrolled temperature. Samples were examined during four days of fermentation.

The experiment found faster changes in protease activity, free amino acids and pH under controlled heating. A shorter fermentation might improve acceptability. This is an experimental adaptation, not proof that every traditional batch requires 35°C or that two days guarantees safety. After fermentation, the beans may be used fresh or dried in the sun. Traditional sources describe drying, but do not establish a reproducible moisture endpoint, safe storage duration or validated microbiological specification.

Regional and historical variations

Bekang is associated with Mizoram's Mizo communities rather than one securely identified village of origin. Ethnographic research describes household production and local market sales, especially by women. The 2015 study of Mizo food-processing techniques was based on interviews with residents and documented small variations between places. It does not divide bekang into a fixed set of named regional styles. The differences it records concern materials, heating arrangements, preservation and subsequent use.

One distinction concerns the wrapping plants. The 2009 account identifies leaves called nuhlhan, associated with Callicarpa arborea, or hnahthial, associated with Phrynium species. The 2015 field study instead records Callicarpa arborea under the local name hnahkiah. These names may reflect differences in local terminology or transcription, but the publications do not resolve the discrepancy. The reported botanical spelling Calliparpa aroria in some older fermentation papers also requires correction against accepted plant taxonomy. An unidentified plant is not a substitute merely because it has broad leaves.

Fermentation arrangements vary as well. Some descriptions refer to bamboo baskets lined with leaves, while another records the traditional chhihri sieve. Fireplace fermentation is prominent, but the 2015 account also mentions placing the covered beans in sunlight. The use of wood ash is explicit in some sources and absent from the abbreviated process diagrams of others. An omitted ingredient in a summary diagram does not prove it is never used. These variations deserve separate source notes rather than a synthetic recipe claiming to represent all Mizo households.

The finished product may remain moist or be sun-dried. Lalthanpuii and colleagues document both direct consumption and drying for later use. The 2009 account records market sales of fresh bekang. Dried forms change the texture and facilitate transport, but a dependable traditional storage period has not been established through water-activity measurements. The influence of smoke, drying weather and storage vessels on the final microbial community also remains insufficiently characterised.

Modern laboratory adaptations provide another distinct category. The 2019 Mizoram experiment compared constant-temperature incubation with exposure to sunlight. The 2021 sequencing study collected bekang from Aizawl vendors on the third, fifth and seventh fermentation days. The later samples had markedly different microbial profiles, but those sampling dates were research observations, not recommendations to extend ordinary fermentation to seven days.

The 2023 comparative metabolomics paper found differences between bekang, Manipur's hawaijar and Nagaland's akhone. These foods share a broad bacterial fermentation mechanism but vary in handling and detected metabolites. Replacing a Mizo fermentation with a standard Japanese natto culture may yield sticky soybeans, but it has not been demonstrated to reproduce the microbial community, aroma or traditional sensory qualities of bekang.

How it is eaten and used

Bekang is eaten as an accompaniment to rice and used as a seasoning in Mizo cooking. It supplies a strong fermented soybean flavour to comparatively simple vegetable and meat preparations. The beans can be eaten fresh, mixed with herbs and chilli, or incorporated into cooked dishes. Their soft texture allows them to break down into a sauce or vegetable mixture. Some preparations use whole beans, while others crush or grind them before serving.

The 2009 ethnographic study describes bekang being prepared as a curry with rice. A 2015 review gives a preparation using salt, green chillies and tomatoes. These ingredients belong to the culinary use of already fermented beans rather than the primary fermentation. Proportions are not standardised. It would therefore be inaccurate to include tomatoes and chillies as required fermentation ingredients.

A 2023 clinical investigation in Mizoram describes bekang-um commonly being eaten as a chutney with herbs such as culantro, spring onion and locally dried chilli. In this form, the fermented beans may be consumed without further cooking. This differs from the curry preparation and is important when assessing food safety, because there is no additional heating stage before eating. The description establishes a contemporary use, not a universal traditional recipe.

Bekang is also an ingredient in bai, a family of Mizo vegetable dishes. A 2021 ethnographic study of Hmar and Paihte food traditions describes ankhapui bai, made with the young shoots and leaves of Marsdenia maculata, alongside salt, ash filtrate and a suitable amount of bekang-um. The same study records tiarhrep bai, prepared with Rhynchotechum ellipticum and other vegetables, in which a small amount of bekang-um is added as a seasoning near the end of preparation.

These dishes show how bekang functions as a concentrated flavour ingredient rather than always being the main portion of food. It can supply fermented soybean flavour to leafy vegetables, bitter ingredients and broths. The ash filtrate used in some vegetable dishes, called ching-al, is a separate culinary ingredient and should not be confused with the wood ash sometimes added during bekang fermentation itself.

A less commonly documented use appears in the 2015 Mizo food-processing survey. The authors record that fermented soybeans are sometimes fried, ground and added to tea, which is regarded as a special preparation in some localities. They do not describe its frequency, flavouring proportions or detailed serving method. This is a local use, not a sign that bekang is ordinarily eaten as tea.

Fresh bekang-um is the preparation itself. Bekang curry, bekang chutney, vegetable bai containing bekang and the roasted or ground tea preparation are dishes made from it. Sun-dried bekang is a processing variation.

Reading results, identifying problems and understanding safety

Traditional bekang is described as sticky, soft and pungent, with a characteristic ammoniacal aroma. These changes are consistent with bacterial growth and protein degradation. The beans may develop surface threads and become easier to crush. Such observations can help describe a familiar product, but they do not establish which microorganisms are present or whether the batch is safe. A food can have the expected smell and texture while containing foodborne pathogens.

The 2019 controlled-fermentation experiment provides useful chemical measurements. Protease and alpha-amylase activity increased during fermentation, alongside viable microbial counts, free amino acids and pH. The controlled samples reached pH 8.47 after four days, while the uncontrolled samples reached approximately 8.34. The strongly ammoniacal fourth-day product was judged over-fermented and less acceptable. This was a sensory and biochemical assessment of the experimental batches, not a validated rule that a lower pH or shorter fermentation is automatically safe.

The 2021 metagenomic study found substantial Staphylococcus populations in its bekang samples, together with Bacillus, Pseudomonas and other genera. Staphylococcus accounted for 52.36% of assigned bacterial sequences on the third day and declined in later samples. This result cannot be translated directly into a count of Staphylococcus aureus or a measurement of enterotoxin. Some Staphylococcus species occur in fermented foods without necessarily causing illness, while others are important pathogens. Identification to species and strain level and appropriate toxin testing are needed before drawing safety conclusions.

The sequencing study also reported increases in other bacterial groups during extended fermentation. However, its results contain an inconsistency in the assignment of a prominent seventh-day sequence percentage between Clostridium and Corynebacterium. The data are inconsistent on this point, so that trend is not an established figure. More generally, relative DNA abundance does not demonstrate that every detected organism was alive, metabolically active or contributing to flavour.

There is direct evidence of foodborne illness associated with contaminated bekang. An outbreak in Chite, Aizawl, occurred in September 2020 and was investigated in a study published in June 2023. Fifty-two people were reported affected. Among eighteen symptomatic patients sampled, seventeen yielded Salmonella isolates, fifteen of which displayed multidrug resistance in the tested panel. The investigation associated the illnesses with bekang-um purchased from a local producer. The main laboratory evidence came from patients' stool samples, not from measuring Salmonella in the original food batch.

A second investigation concerned Keifang in Saitual District in September 2024 and was published in April 2026. Forty of fifty-eight exposed people became ill. Researchers recovered atypical enteropathogenic Escherichia coli from all forty affected individuals and from one leftover fermented soybean sample. The connection between contaminated bekang and the outbreak was therefore supported by epidemiological information and food-sample microbiology. This is especially significant because the product may be eaten without subsequent cooking.

These incidents do not mean traditional bekang is inherently unsafe, but they show that spontaneous warm fermentation cannot be assumed protective. Food-grade materials, safe cooking water, hygienic leaf and equipment handling, protection against insect contamination, appropriate process controls and product-specific microbiological testing matter. Firewood ash should not come from treated or contaminated timber. Nor does adding ash provide a validated pathogen-control step. Bacterial populations detected in samples are not starters unless they are identified and assessed.

Sun-drying is also insufficiently validated as a storage control. Traditional sources describe dried bekang being kept for later use, but do not provide measured final water activity, packaging specifications or reliable shelf-life limits. Biogenic amines and bacterial toxins have not been comprehensively characterised across the traditional product. Soybean remains an allergen after fermentation. A practical recipe suitable for unsupervised home production would require validated microbiological controls rather than relying on elapsed time, temperature, aroma or visible stickiness alone.