Fermentation is one of the primeval and most significant food processing techniques in human history, having been employed in Asian civilisations as early as 8000 BCE, according to archaeological evidence
(Marco et al., 2017). Fermented foods have indubitably played important roles in food preservation, flavour and texture enhancement, nutritional value enhancement and microbiological safety assurance across continents. Fermentation is a multifaceted process; rather, it is a diverse constellation of microbial and biochemical transformations specific to geographical regions, cultural histories, available substrates and ecological environments, as highlighted in systematic global studies (
García-Barón et al., 2025;
Melini et al., 2019). Fermentation is one of the oldest food biotechnologies used by human societies to improve nutritional content, shelf life and sensory attributes. Beneficial bacteria’ metabolic processes are what transform complex substrates into safer, more flavourful and easier to digest food. India’s fermented food diversity has developed in response to local climate, culture, agricultural practices and dietary needs. Traditional fermentation has considerable value for food preservation, nutritional improvement and health, but many indigenous products remain geographically underexplored (
Sathe and Mandal, 2016). In India, traditional fermented foods are deeply ingrained in the country’s culinary heritage and everyday dietary practices, varying significantly across regions due to differences in climate, culture, raw materials and community knowledge systems
(Rawat et al., 2018).
Fermented foods in the global context
Fig 1
(Tamang et al., 2016) shows microscopic view of Lactic acid bacteria (LAB),Yeasts, moulds, Bacillus species, acetic acid bacteria and other dominant microbial guilds can be used to broadly classify fermented foods worldwide. Cereals, fruits, vegetables, legumes, dairy, meat, fish and drinks are some of these substrates. A remarkable variety of fermented products, including kimchi, sauerkraut, kombucha, kefir, miso, natto, tempeh, gari, pozol, chicha, togwa, injera and many traditional fish products, can be found in countries in East and Southeast Asia, Eastern Europe, Africa and Latin America
(Marco et al., 2017). In addition to their culinary value, the functional and health promoting potential of these substances is now extensively recognised, which include anti-inflammatory, immunomodulatory, antioxidant, antidiabetic, cardioprotective and digestive benefits (
Do Prado et al., 2022;
Shahbazi et al., 2021).
Fermented foods in India
India boasts a highly varied array of traditional fermented foods, attributed to its numerous ethnic communities, diverse climates and various agricultural practices
(Rawat et al., 2018). Individuals frequently utilize their traditional wisdom to prepare these foods, which relies on natural fermentation initiated by the local microbiota found in the surroundings, tools and materials
(Tamang et al., 2016). Fermentation practices in India have evolved in conjunction with cultural identity, geography and subsistence patterns. Indigenous communities have historically utilised fermentation to preserve seasonal produce and enhance digestibility, especially in tropical regions conducive to rapid food spoilage
(Ghosh et al., 2015). Fig 2 shows that traditional fermented foods of Northeast India are produced through spontaneous fermentation or community-maintained starter cultures involving LAB, yeasts and
Bacillus spp.
These fermented foods can improve digestibility, enhance vitamins and amino acids and provide potential probiotic and antioxidant benefits.
Importance of fermented foods in Northeast India
The Northeast region of India, comprising Assam, Arunachal Pradesh, Nagaland, Manipur, Meghalaya, Mizoram, Tripura and Sikkim, is recognized globally as a hotspot for biodiversity and a region rich in diverse culinary traditions among various ethnic groups. The indigenous populations in this region are known for producing over 250 types of fermented foods and beverages
(Chowdhury et al., 2019). Various fermentation methods have emerged due to the challenging landscape, moist climate, diverse agricultural biodiversity and a long-standing dependence on forest and farm products. These foods have several uses, including preserving seasonal crops, improving palatability, offering probiotic health benefits.
The general classifications that follow can be used to group traditional fermented foods from the Northeast:
(a) Fermented soybean foods such as
Kinema,
Hawaijar and
Tungrymbai.
(b) Fermented vegetables including
Gundruk,
Sinki and
Mesu.
(c) Fermented bamboo shoot products.
(d) Fermented fish products, such as
Ngari and
Hentak.
(e) Cereal-based fermented alcoholic beverages like
Chhang,
Apong and
Xaj (
Ignat et al., 2020).
Data sources and literature search strategy
This review was conducted using a comprehensive search of peer-reviewed scientific literature to evaluate the diversity of traditional fermented foods of Northeast India, their microbial ecology, biochemical changes, functional properties and impact on gut microbiota. The literature search was performed using the electronic databases Scopus, Web of Science, ScienceDirect, SpringerLink, Google Scholar and Wiley Online Library.
The literature search covered studies published from January 2000 to March 2026 and the final search was conducted on 15 March 2026.
The search strategy employed combinations of Medical Subject Headings and free text keywords using Boolean operators (AND, OR).
The following search terms were used:
“Fermented foods” AND “Northeast India”.
“Traditional fermented foods” AND “India”.
“Fermented soybean” OR “Kinema” OR “Hawaijar” OR “Axone” OR “Tungrymbai”.
“Fermented fish” OR “Ngari” OR “Hentak” OR “Shidal” OR “Berma”.
“Fermented bamboo shoot” OR “nyari” OR “Soidon”.
“Rice beer” OR “Apong” OR “Zutho” OR “Xaj-pani”.
“Gut microbiota” AND “Fermented foods”.
“Lactic acid bacteria” OR “Bacillus species”.
“Functional foods” AND “Probiotics”.
To ensure comprehensive coverage, the reference lists of selected articles were manually screened to identify additional relevant studies that were not retrieved during the electronic database search.
The final dataset consisted of peer-reviewed original research articles, systematic reviews, ethnographic studies and metagenomic investigations describing fermented foods of Northeast India, including soybean, fish, bamboo shoot, vegetable and cereal-based fermented products. Global studies on functional fermented foods, microbial ecology, gut microbiota and biochemical changes during fermentation were also included to provide broader scientific context. This review is based entirely on published primary and secondary literature to ensure scientific reliability, authenticity and comprehensive coverage of the available evidence.
Inclusion criteria
Studies were included if they met one or more of the following criteria:
Investigated traditional fermented foods and beverages of Northeast India.
Reported microbiological, biochemical, nutritional, or functional characteristics of fermented foods.
Included molecular, metagenomic, or microbial ecology analyses.
Evaluated probiotic potential, gut microbiota modulation, or health benefits.
Were peer-reviewed original research articles, systematic reviews, or ethnographic studies published in English.
Described traditional fermentation practices or compared Northeast Indian fermented foods with global fermented foods.
Exclusion criteria
The following publications were excluded:
Conference abstracts, editorials, book chapters, dissertations and unpublished reports.
Studies unrelated to traditional fermented foods.
Industrial, pharmaceutical, or biofuel fermentation studies not associated with food.
Consumer preference or tourism studies without microbiological or nutritional relevance.
Duplicate publications and studies lacking sufficient methodological details or scientific evidence.
Study selection and data extraction
Titles and abstracts of the retrieved records were initially screened for relevance. Full-text articles meeting the inclusion criteria were further evaluated. Duplicate studies were removed prior to eligibility assessment. Data from the selected studies were extracted using a standardized data extraction format that included the following variables: author(s), publication year, study location, fermented food, raw material, fermentation process, dominant microorganisms, biochemical changes, nutritional composition, functional properties, gut microbiota-related findings, key outcomes and identified research gaps.
Data synthesis
The extracted data were synthesized using a narrative approach. Fermented foods were categorized into fermented soybean products, fermented fish products, fermented bamboo shoot products, fermented vegetables and cereal-based fermented beverages. The findings were organized under the themes of diversity of fermented foods, microbial ecology, biochemical changes during fermentation, functional and health benefits, safety and fermentation management and gut microbiota modulation. Comparative tables were prepared to summarize the microbial diversity, nutritional characteristics, functional properties and health implications of traditional fermented foods across the Northeastern states of India.
Global perspective on fermented foods
Fermentation is among the oldest and most widely utilized methods of food transformation, having developed independently in various human cultures as a practical and economical means for preservation, improving taste and enhancing nutrition
(Das et al., 2016). Historical records indicate that as societies have evolved and adapted to their local environments, fermentation has also advanced, leading to the development of distinct regional items like Fig 3 shows kimchi fermented food, miso, natto, kefir, tempeh, injera, gari and various fermented fish sauces and pastes
(Martin et al., 2024). The wide variety of fermented foods around the world is shaped by the interplay of available raw materials, local microbial communities, methods of preparation and traditional knowledge; thus, specific microbial communities like lactic acid bacteria (LAB), yeasts, Bacillus spp. and filamentous fungi become predominant in particular food types
(Tamang et al., 2016).
Microbial ecology of global fermented foods
From a biological standpoint, fermentation frequently modifies phytochemicals and macronutrients to increase their bioavailability and produce new beneficial molecules. Yeast fermentation produces ethanol and aromatic volatiles while also enriching amino acid levels; Bacillus-driven alkaline fermentation is especially efficient at breaking down proteins and releasing peptides with potential fibrinolytic or antihypertensive effects; filamentous fungi provide saccharifying enzymes that release fermentable sugars from starches; and lactic acid bacteria (LAB) fermentation usually acidifies substrates, produces B vitamins and produces exopolysaccharides and small bioactive peptides
(Tamang et al., 2020). Advanced analytical approaches, including metabolomics and multi-omics sequencing, have revealed that these fermentation processes produce antioxidant phenolics, γ-aminobutyric acid (GABA), isoflavone aglycones, short-chain fatty acid (SCFA) precursors and other compounds linked to benefits for cardiometabolic health, neuroprotection and immune regulation
(Melini et al., 2019; Soibam and Ayam, 2018). The growing interest in the health impacts of fermented foods has coincided with advancements in microbiome research. Numerous reviews compile evidence suggesting that fermented foods can introduce living microorganisms with probiotic properties, affect the variety of gut microorganisms and generate metabolites that have localized effects in the intestine or systemic effects once absorbed
(Skowron et al., 2022). Fermentation can also enrich the product with amino acids, vitamins, minerals, prebiotic and probiotic components while reducing anti-nutritional compounds such as phytic acid and tannins
(Ramasamy et al., 2025).
Fermented foods in the Indian context
In India, the customs of fermentation are deeply rooted and vary significantly by region. Throughout the subcontinent, items such as idli and dosa (rice-legume batters), dhokla (fermented legume cake), an array of dairy products (dahi, mishti doi) and locally specific drinks (haria, chhang, apong) reflect a rich and diverse history of household and small-scale fermentation
(Rawat et al., 2018; Tamang et al., 2020). Indian fermentation practices frequently depend on spontaneous or semi-defined starter cultures (
e.
g., marcha, hamei, emao), whose microbial communities echo the local plant and animal resources, utensils and surrounding microbiota
(Tamang et al., 2016). Studies have shown that these techniques can change the chemical composition of substrates by reducing anti-nutritional factors (such as phytates and trypsin inhibitors), improving concentrations of free amino acids and vitamins, as well as producing antioxidant and antimicrobial compounds
(Leeuwendaal et al., 2022; Melini et al., 2019). The Northeast region of India, comprising Arunachal Pradesh, Assam, Meghalaya, Mizoram, Manipur, Nagaland, Tripura and Sikkim, is notable for the diversity and richness of its fermented foods.
Fermented foods in the context of Northeastern India
Research focused on the functional and health aspects of Northeast fermented foods is increasing, but it remains relatively limited. Studies conducted
in vitro and on animals indicate that various fermented fish and soybean products possess antioxidant, anti-inflammatory, antimicrobial and fibrinolytic properties; however, human dietary studies and observational research show only some supportive links to digestive comfort and culturally defined well-being, lacking robust clinical trials
(Chowdhury et al., 2019; Devi Nongmaithem et al., 2023;
Majumdar et al., 2016). Ethnographic studies have consistently uncovered more than two hundred distinct traditional fermented foods in Northeast India, many of which are vital to local diets, cultural practices and seasonal economic activities
(Chowdhury et al., 2019; Das et al., 2016). In this region, fermentation utilizes an abundant supply of freshwater fish (used for ngari, hentak, shidal), soybeans and other legumes (kinema, tungrymbai), bamboo shoots,as well as rice and millet to produce both alcoholic and non-alcoholic drinks (apong, chubitchi, haria), in combination with a variety of leafy and tuberous ingredients. The dominance of both alkaline (characterized by Bacillus) and acid (dominated by LAB) fermentation pathways in NE India makes it an intriguing natural laboratory for comparative fermentation research, linking the trends observed in East/Southeast Asia and South Asia
(Das et al., 2016; Tomar et al., 2023).
Microbial ecology of Northeast Indian fermented foods
Traditional processing methods, ambient environmental microbiota and native substrates interact intricately to shape the microbial ecology of Northeast Indian fermented foods. Numerous fermentations throughout the region are controlled by spontaneous processes that depend on the natural microorganisms found on raw materials, utensils and preparation surfaces, according to thorough microbiological investigations
(Tamang et al., 2016). In the fermentation of bamboo shoots, vegetables and drinks, lactic acid bacteria (LAB) are the most prevalent microorganisms, whereas Bacillus species play a significant role in the fermentation of fish and soybeans.
Fermented fish products
Fermented fish items like ngari, hentak, shidal and namsing prominently feature proteolytic Bacillus species. Preliminary investigations using both culture techniques and molecular methods identified
Bacillus subtilis,
B.
licheniformis,
B.
cereus and
B.
pumilus as common isolates that play a role in protein breakdown, improve flavor and facilitate the production of bioactive peptides
(Majumdar et al., 2016; Thapa et al., 2004). These microorganisms decompose substantial fish proteins into peptides and free amino acids like glutamate, which enhance the umami taste. Besides proteolytic activity, Bacillus spp. also generates antimicrobial substances, alkaline enzymes and fibrinolytic peptides that may offer health advantages (
Muzaddadi, 2013). Lactic acid bacteria (LAB) such as Lactobacillus plantarum and L. fermentum are also found in fermented fish products, typically aiding in acidification, flavour enhancement and the suppression of pathogens.
Soybean fermentations
Fermentations based on soybeans including kinema, tungrymbai, hawaijar and bekang show a rich microbial diversity, with Bacillus subtilis group organisms being significantly prevalent (
Chettri and Tamang, 2015). Similar to Japanese natto and Korean cheonggukjang, these alkaline ferments undergo considerable protein degradation, leading to an increase in free amino acids, bioactive peptides and the transformation of isoflavone glycosides into more easily absorbable aglycones such as daidzein and genistein (
Do Prado et al., 2022;
Melini et al., 2019). The involvement of LAB, including species from Lactobacillus and Weissella, contributes to flavor enhancement and moderate acidification. It is found that amalyese,an important enzyme found in fermented soyabean hydrolyzes carbohydrates to give a sweet taste to the product. The organic acid content in fermented soyabean is higher but depends on different fermentation method
(Shin et al., 2020).
Bamboo shoot fermentations
Fermented bamboo shoot products such as khorisa, soibum, soidon and mesu possess a unique sourness primarily shaped by lactic acid bacteria (LAB). Culture-based studies consistently identify
Lactobacillus plantarum,
L.
brevis,
Pediococcus pentosaceus,
Weissella cibaria and
Leuconostoc mesenteroides as the principal species
(Das et al., 2016; Soibam and Ayam, 2018). Bamboo shoots naturally have cyanogenic glycosides, but LAB fermentation greatly diminishes cyanide levels, converting potentially harmful components into safe and nutritionally improved foods
(Bardhan et al., 2026).
Rice and millet-based fermented beverages
Beverages that contain alcohol or have low alcohol content, like apong (Assam), xaj-pani, jou (Tripura), chubitchi (Garo Hills) and zutho (Nagaland) are made using dried starter cultures that consist of a mixture of molds (Rhizopus, Mucor, Aspergillus), yeasts (Saccharomyces cerevisiae, Candida tropicalis) and LAB
(Ghosh et al., 2015; Tamang et al., 2020). These multi-organism starters resemble marcha, murcha and hamei used in Eastern Himalayan regions. Recent metagenomic analyses of Assamese rice beer starters feature complex microbial communities with significant functional potential, including genes for starch breakdown, alcohol fermentation, organic acid production, vitamin biosynthesis (B-complex) and stress tolerance
(Borah et al., 2021).
Fermented vegetables and mixed substrates
In Northeast India, leafy and assorted vegetables are often fermented through natural processes driven by lactic acid bacteria (LAB). Preparations like gundruk, fermented pumpkin shoots, mustard greens and mixed vegetable pickles display LAB communities that are comparable to those found in bamboo shoot fermentations, even though the makeup of the substrate significantly influences microbial succession
(Bardhan et al., 2026). Fermentations based on vegetables typically demonstrate a high potential for antioxidants due to the LAB-mediated release of phenolics and the natural phytochemical content present in leafy greens (
Sarma and Gupta, 2022).
Biochemical changes in fermented foods from Northeast India
Biochemical research indicates that fermentation significantly modifies the chemical structure, nutritional content and functional characteristics of fermented foods from Northeast India. Key biochemical processes include proteolysis, carbohydrate degradation, lipid modification, detoxification, vitamin synthesis and enhancement of phenolic compounds. Fig 4 shows that fermentation drives key biochemical processes including proteolysis, carbohydrate degradation, lipid modification, phenolic enhancement, vitamin synthesis and detoxification thereby improving the nutritional, functional and safety properties of foods Fermentations of fish and soybeans experience extensive proteolysis facilitated by Bacillus species. These microorganisms generate various proteases, peptidases and fibrinolytic enzymes that decompose large proteins into peptides and amino acids (
Chettri and Tamang, 2015;
Majumdar et al., 2016). Free amino acids like glutamate, alanine and leucine boost umami and kokumi flavours. Notably, bioactive peptides produced through the breakdown of proteins demonstrate antioxidant, antihypertensive (ACE-inhibitory), antimicrobial and fibrinolytic benefits. Fermentations based on cereals involve molds that produce amylolytic and saccharifying enzymes, transforming complex carbohydrates into sugars that can be fermented. Species like Rhizopus and Aspergillus plays an essential role in this mechanism
(Ghosh et al., 2015). The transformation of lipids in fermented fish products leads to unique flavours and possible health benefits. The activity of lipase from
Bacillus spp. generates free fatty acids, some of which can be oxidized into aldehydes and ketones that enhance aroma
(Majumdar et al., 2016). Factors cyanogenic glycosides found in bamboo shoots need to be detoxified before they can be consumed. LAB fermentation effectively decreases cyanide levels through both enzymatic breakdown and acid hydrolysis
(Das et al., 2016). Fermenting soybeans leads to a considerable reduction in trypsin inhibitors, phytic acid and tannins, thereby improving protein digestibility
(Tamang et al., 2016).
Functional roles and health implications
a) Antioxidant properties
Rice drinks, bamboo shoot products and pickled vegetables demonstrate significant antioxidant capabilities thanks to both microbial activity and components derived from the substrate. The process of fermentation with lactic acid bacteria (LAB) increases the concentration of free phenolic compounds and improves the ability to neutralize DPPH radicals
(Ghosh et al., 2015; Meena and Taneja, 2022). Additionally, fermented soy products and fish are rich in antioxidant peptides that counteract reactive oxygen species.
b) Anti-inflammatory and immunomodulatory effects
LAB strains obtained from conventionally fermented foods in Northeast Asia have exhibited anti-inflammatory properties, including the suppression of pro-inflammatory cytokines like TNF-α and IL-6 while promoting anti-inflammatory cytokines such as IL-10
(Shahbazi et al., 2021).
c) Gut microbiota modulation
Recent research indicates that fermented foods originating from Northeast Asia can change the makeup of gut microbiota. LAB and Bacillus strains display characteristics similar to probiotics, allowing them to survive gastric transit and temporarily colonize the gut
(Leeuwendaal et al., 2022). The fermentation of indigestible food components such dietary fibres, which produces short-chain fatty acids (SCFAs) like acetate, propionate and butyrate, is one of the gut microbiota’s primary functions. In addition to providing colonocytes with energy, these metabolites support the integrity of the intestinal barrier and control inflammatory reactions
(Koh et al., 2016).
The host immune system and the gut microbiota are intimately related. It promotes tolerance to helpful bacteria and guards against pathogenic invasion by supporting the growth and maturity of immune responses
(Chilton et al., 2015). Dysbiosis, defined as an imbalance in microbial composition, has been associated with a range of diseases, including inflammatory bowel disease (IBD), obesity, type 2 diabetes and even neurological disorders through the gut brain axis (
Sarma and Gupta, 2022). The Fig 5 illustrates that fermented foods provide multiple health benefits through antioxidant and anti-inflammatory activities, immunomodulatory effects and beneficial modulation of the gut microbiota, including potential probiotic effects.
Safety, risks and fermentation management
Differences in home fermentation processes lead to variable microbial profiles and nutrient content. Future efforts should focus on standardized starter cultures, regulated fermentation environments and enhanced quality assurance systems (
Devi Nongmaithem et al., 2023). Fermentation practices in Northeast India aid in the preservation of perishable foods within a humid subtropical climate, promote food security throughout the year and strengthen cultural identities
(Das et al., 2016; Mridul, 2018). Sustainable commercialization has the potential to bolster local economies while maintaining cultural authenticity. Issues related to biogenic amines (such as histamine), pathogens and various fermentation conditions have been documented
(Skowron et al., 2022).
Traditional fermented foods of Northeast India represent an important combination of indigenous knowledge, microbial diversity, nutritional enhancement and cultural heritage. Similar to globally recognized fermented foods such as kimchi, natto, miso, kefir and tempeh, these foods possess significant functional and probiotic potential due to the activity of beneficial microorganisms and fermentation-derived metabolites
(Tamang et al., 2020). However, compared with global fermented foods, many Northeast Indian fermented products remain scientifically underexplored despite their remarkable diversity.
Nutritional and functional importance
Fermentation improves the nutritional quality, digestibility, flavor and shelf life of foods through microbial activities such as proteolysis, carbohydrate degradation, vitamin synthesis and detoxification of anti-nutritional compounds (
Do Prado et al., 2022;
Tomar et al., 2023). Table 1 represented the fermented foods reported from Assam include fish-based, rice-based, vegetable, bamboo shoot and other traditional products, demonstrating considerable nutritional and functional diversity. These products provide proteins, minerals, dietary fibre, amino acids, organic acids and other bioactive compounds, while fermentation contributes to improved digestibility, preservation and development of characteristic flavours. Fermented soybean foods including kinema, hawaijar, tungrymbai and axone are rich in proteins, amino acids and bioactive peptides produced mainly by Bacillus subtilis group organisms (
Chettri and Tamang, 2015). In Manipur, hawaijar represents an important alkaline fermented soybean food characterized by high protein content, increased soluble nitrogen, conversion of isoflavone glycosides to aglycones and reduction of anti-nutritional factors shown in Table 2. Similarly, fermented fish products such as ngari possess enhanced flavor compounds and antioxidant peptides due to extensive protein breakdown
(Majumdar et al., 2016).
The fermented foods documented from Meghalaya further demonstrate the nutritional importance of traditional fermentation shown in Table 3. Tungrymbai is a protein-rich fermented soybean product with enhanced free amino acids and peptides and improved digestibility, whereas tungtap which is fermented dried fish provides protein and fat together with intensified flavour compounds. Fermented foods of Mizoram include soybean, pork-based and leafy vegetable products with different nutritional and functional properties shown in Table 4. Bekang, an alkaline fermented soybean food, is characterized by high protein, soluble nitrogen, peptides and reduced anti-nutritional factors. Nagaland, axone or akhuni is an important alkaline fermented soybean product with high protein, elevated soluble nitrogen, increased isoflavone aglycones and reduced trypsin inhibitors shown in Table 5. Fermented fish products are particularly important among the traditional foods of Tripura shown in Table 6. Shidal is characterized by high protein and fat, omega-3 fatty acids, calcium and phosphorus, while extensive proteolysis produces free amino acids and peptides. The fermented foods of Arunachal Pradesh apong, poka and jaan are carbohydrate-rich fermented beverages containing organic acids and some B-vitamins. Fermented leafy vegetables and algae-based foods provide fibre and micronutrients such as iron, calcium and β-carotene shown in Table 7. Sikkim’s fermented foods are nutritionally valuable, with Kinema providing high-quality protein and bioactive compounds, Mesu supplying fibre and detoxified bamboo shoots and Churpi contributing protein, fat, calcium and improved digestibility as shown in Table 8.
Lactic acid bacteria (LAB) and Bacillus species play major roles in fermentation by producing organic acids, enzymes, bacteriocins and bioactive compounds that improve preservation and functional properties
(Tamang et al., 2020). These foods therefore serve as promising natural functional foods and nutraceutical resources.
Fermented foods and gut microbiota
Recent studies suggest that traditional fermented foods may positively influence gut microbiota composition and intestinal health
(Leeuwendaal et al., 2022). LAB and Bacillus strains isolated from Northeast Indian fermented foods exhibit probiotic characteristics such as acid tolerance, bile resistance and antimicrobial activity (
Meena and Taneja, 2022). These microorganisms may help improve gut microbial balance and intestinal homeostasis.
The fermented foods of Assam shown in Table 1 contain diverse microbial communities, particularly LAB and
Bacillus species, associated with fermented fish, rice, vegetables and bamboo shoots. These microorganisms contribute to fermentation, preservation and the development of functional properties. In Manipur shown in Table 2, fermented soybean and bamboo shoot products are mainly associated with Bacillus and LAB. Their reported microbial diversity indicates potential functional and probiotic characteristics. The fermented foods of Meghalaya shown in Table 3 contain Bacillus, LAB, yeasts and moulds, particularly in fermented soybean, fish and rice-based products. These microorganisms contribute to nutrient transformation and characteristic fermentation properties. In Mizoram, fermented soybean and leafy vegetable products predominantly involve Bacillus and LAB shown in Table 4. Their microbial activities contribute to acidification, preservation and improvement of fermentation-related properties. The fermented foods of Nagaland, particularly axone, ghalo and zutho, involve Bacillus, LAB, yeasts and moulds shown in Table 5. This mixed microbial diversity contributes to the characteristic nutritional, sensory and fermentation properties of these traditional foods. In Tripura, fermented fish products such as shidal/seedal and berma are mainly associated with Bacillus and halotolerant bacteria, with some other microorganisms reported during fermentation shown in Table 6. These microbial communities contribute to proteolysis, flavour development and preservation. The fermented foods of Arunachal Pradesh include rice- and millet-based beverages, fermented dairy products and leafy vegetable and algae-based foods, their fermentation involves yeasts, moulds, LAB and milk-associated LAB shown in Table 7, contributing to fermentation, digestibility, preservation and characteristic food properties. In Sikkim shown in Table 8, Kinema is an alkaline fermented soybean food dominated by the
Bacillus subtilis group, with minor LAB and is characterized by high protein and soluble nitrogen content. Mesu, a fermented bamboo shoot product, is predominantly associated with LAB such as
Lactobacillus plantarum,
L.
brevis,
Pediococcus and
Weissella, contributing to acidification and preservation. Churpi, a fermented milk product, contains milk-associated LAB including
Lactobacillus,
Lactococcus and
Streptococcus and provides protein, fat and calcium while improving digestibility.
Fermentation-derived metabolites, especially short-chain fatty acids (SCFAs), contribute to immune regulation, intestinal barrier integrity and anti-inflammatory effects
(Koh et al., 2016). However, most studies are still limited to laboratory and animal investigations and more human clinical studies are required to validate their therapeutic benefits.
Industrial and commercial potential
Traditional fermented foods of Northeast India possess considerable commercial potential because of increasing global demand for probiotic and naturally fermented foods. Products such as fermented soybean foods, rice beverages and bamboo shoot ferments may be developed into value-added functional foods and nutraceutical products (
Devi Nongmaithem et al., 2023).
Commercialization could support local economies and preserve traditional food knowledge systems. However, large-scale production requires standardization of fermentation methods, starter cultures, packaging and quality control measures to ensure product consistency and safety
(Das et al., 2016).
Challenges and research gaps
Despite their nutritional and therapeutic importance, several challenges limit the wider acceptance and commercialization of Northeast Indian fermented foods. Traditional household fermentation practices often result in inconsistent microbial composition, product quality and safety
(Skowron et al., 2022). Risks associated with pathogenic contamination and biogenic amine formation remain important concerns.
Another major limitation is the lack of advanced molecular and clinical studies. Most available research is culture-dependent and descriptive. Application of metagenomics, metabolomics and multi-omics approaches can provide deeper understanding of microbial diversity, metabolic pathways and probiotic potential
(Koh et al., 2016). Furthermore, well-designed clinical studies are needed to establish scientifically validated health benefits.
Preservation of indigenous fermentation knowledge is also important, as modernization and changing food habits threaten many traditional practices. Sustainable documentation, scientific validation and community-based conservation strategies are therefore essential for protecting the culinary heritage of Northeast India while promoting its role in future functional food systems
(Ghosh et al., 2015; Dutta, 2018).
Critical evaluation, research restrictions and prospects
The majority of research is restricted to microbe identification, nutritional profile and in vitro analysis, despite earlier studies showing the nutritional and physiological significance of traditional fermented foods of Northeast India. There is still no scientific proof of their probiotic effectiveness, regulation of the gut microbiota and therapeutic advantages in people
(Devi et al., 2023; Marco et al., 2017). Furthermore, differences in conventional fermentation methods, raw materials and environmental circumstances lead to variable results and restrict the repeatability and comparability of previous research
(Skowron et al., 2022).
The restricted use of sophisticated molecular techniques is another significant drawback. The majority of published research uses culture-dependent techniques, which could lead to an underestimation of microbial diversity. To gain a deeper understanding of microbial succession, functional genes and metabolite synthesis during fermentation, metagenomics, metabolomics and other multi-omics methods must be integrated
(Ignat et al., 2020).
To confirm the impact of these fermented foods on gut microbiota and human health, future research should concentrate on standardised fermentation procedures, thorough food safety evaluations and carefully planned clinical trials. The scientific validation, sustainable commercialisation and international acceptance of indigenous fermented foods from Northeast India as useful dietary resources would be bolstered by such findings.
