Chakapura: The Fermented Mustard Probiotic of Assam

Chakapura, also known as Chak Hao in some communities, is a traditional fermented mustard seed product from the state of Assam in Northeast India. This pungent, flavorful condiment occupies a unique place in Assamese cuisine, distinct from the better known Kahudi and Kharoli, which are also fermented mustard preparations but involve different processes and microbial communities . Chakapura is typically prepared by grinding mustard seeds into a paste, wrapping the paste in specific plant leaves, and allowing it to undergo spontaneous fermentation. The result is a probiotic rich, enzyme dense paste used as a side dish, a digestive aid, and a flavor enhancer for various Assamese meals.

Unlike many other fermented foods that rely on lactic acid bacteria alone, Chakapura and its regional relatives are dominated by endospore forming Bacillus species, which contribute to its unique texture, flavor, and health benefits . This microbial distinction makes Chakapura a valuable addition to the family of traditional probiotic foods.

Cultural Roots and Nomenclature

The mustard based fermented products of Assam have been consumed for centuries, with each community developing its own variation. The general term for fermented mustard seeds in Assamese is Kahudi, while Kharoli refers to a version that includes an additional ingredient, typically dried fish or other flavorings . However, the specific preparation known as Chakapura or Chak Hao is distinguished by the method of fermentation, which involves wrapping the mustard paste in leaves, often of the Khorisa plant or other locally available species.

These local and artisanal condiments are slowly but steadily finding their way from household kitchens to urban platters. New cottage food industries are growing around these food items, catering to the needs of food enthusiasts who seek out traditional fermented foods for their unique organoleptic characteristics, nutritional composition, and perceived health benefits .

Traditional Significance

In Assamese households, fermented mustard products like Chakapura are consumed in small quantities as side dishes to the main meal. They are cherished due to their unique flavor, their ability to stimulate digestion, and their preservative qualities, which allow them to be stored for extended periods without refrigeration. The preparation of Chakapura is traditionally a household art, with recipes and techniques passed down through generations. The choice of leaves used to wrap the mustard paste, the duration of fermentation, and the addition of salt or other spices are all variables that distinguish one family's Chakapura from another's.

The Microbiology: A Bacillus Dominated System

Recent scientific research has provided significant insights into the microbial communities associated with traditional mustard seed fermentation in Assam. A 2022 study using advanced LC-MS based metabolomics and NGS based microbial diversity analysis revealed a distinctive microbial profile for these products .

Dominant Microorganisms

The key functional microbes present in fermented mustard preparations include:

Bacillus species

Unlike many fermented foods that are dominated by lactic acid bacteria, fermented mustard products in Assam are characterized by the dominance of endospore forming and proteolytic Bacillus species . Bacillus species are known for their ability to produce powerful enzymes, including proteases and amylases, which break down complex proteins and carbohydrates. The endospores of Bacillus are highly resistant to heat, acid, and other environmental stresses, allowing them to survive the fermentation process and remain viable in the final product.

Specific Bacillus strains identified in related fermented mustard samples include Bacillus flexus and Bacillus amyloliquefaciens . Bacillus amyloliquefaciens, in particular, is known for its production of bioactive compounds and enzymes that may contribute to the functional properties of the fermented product.

Paenibacillus species

These bacteria are related to Bacillus and have been identified in fermented mustard and bamboo shoot products from the region . Identified species include Paenibacillus favisporus, Paenibacillus cineris, and various unclassified Paenibacillus species .

Lysinthacillus species

The same 2022 study revealed the abundance of Lysinthacillus in Kharoli samples, indicating that different mustard based ferments may have distinct microbial signatures .

Staphylococcus species

Molecular identification of bacteria from fermented mustard seeds has shown that Staphylococcus species, including Staphylococcus fleurettii, Staphylococcus succinus, Staphylococcus virulinus, and Staphylococcus pasteuri, are also present in these products .

Lactic Acid Bacteria

While Bacillus species dominate, lactic acid bacteria are also present. Molecular analysis has identified Lactobacillus brevis and Lactobacillus Plantarum in fermented mustard and bamboo shoot samples . These LAB contribute to the tangy flavor profile and add to the probiotic diversity of the product.

Yeast like organisms

Fermented mustard samples have also yielded yeast like colonies, indicating that yeasts play a role in the fermentation ecosystem .

A comparison of the bacterial diversity in fermented mustard versus fermented bamboo shoot samples showed that Staphylococcus species were dominant in mustard seed samples, while Bacillus, Oceanobacillus, Lactobacillus, and Paenibacillus were more abundant in bamboo shoot samples . This suggests that the substrate significantly influences which microbes come to dominate the fermentation.

Bioactive Metabolites and Functional Compounds

The integrated metabolomics study of Kahudi and Kharoli revealed the abundance of many therapeutically important bioactive metabolites .

Identified Bioactive Metabolites

Sinapine

This alkaloid is found in mustard seeds and has documented antioxidant and radioprotective properties. Sinapine is known to cross the blood brain barrier and has been studied for its neuroprotective potential.

Indole 3 Carbinol

This compound is produced from glucosinolates present in mustard seeds during fermentation. Indole 3 carbinol has been extensively studied for its anticancer properties, particularly its ability to modulate estrogen metabolism and induce apoptosis in cancer cells.

Gamma Linolenic Acid (GLA)

An omega 6 fatty acid with anti inflammatory properties. GLA is known to support skin health, reduce inflammation, and may help manage conditions such as rheumatoid arthritis and eczema.

Beta Sitosterol Acetate

A plant sterol with documented cholesterol lowering and anti inflammatory effects. Beta sitosterol has also been studied for its potential benefits in benign prostatic hyperplasia.

3 Butylene Glucosinolate

A glucosinolate compound that, when hydrolyzed, produces bioactive isothiocyanates with anticancer and antimicrobial properties.

Erucic Acid

A long chain fatty acid found in mustard seeds. While high levels of erucic acid are subject to dietary restrictions in some contexts, in the small quantities consumed in fermented mustard condiments, it contributes to the unique fatty acid profile of the product.

The presence of these bioactive metabolites, combined with the live probiotic bacteria, makes Chakapura a functional food with potential health benefits beyond basic nutrition.

Probiotic Diversity and Peak Viability

The specific cell counts of microbes in Chakapura vary based on the preparation method and fermentation conditions, but scientific studies on related fermented mustard products provide useful benchmarks.

Viable Cell Counts

Research on fermented mustard seed samples has documented bacterial colony counts in the range of 10⁵ to 10⁶ CFU per gram . A study investigating fermented mustard samples from Nalbari and Dhekiajuli districts of Assam recorded counts of 113 x 10⁵ and 179 x 10⁶ per gram for different samples, with yeast counts ranging from 11 x 10⁵ to 25 x 10⁵ CFU per gram . These counts, while lower than those found in fermented dairy products, still provide a substantial dose of live microbes, particularly when the condiment is consumed regularly in small quantities.

The Peak Stage

The stage when probiotic diversity as well as count is at its highest is during the active fermentation period, typically after 3 to 7 days of fermentation at ambient temperature, before the product is transferred to longer term storage. At this point, the Bacillus species have completed their vegetative growth phase, producing enzymes that break down the mustard seed components, while LAB and other bacteria have also proliferated. Once the product is stored in a cool place or refrigerated, the metabolic activity of the microbes slows, though the endospores of Bacillus remain viable for extended periods.

Preparation Guidelines for Chakapura

The traditional preparation of Chakapura follows a specific methodology. The fermentation is spontaneous and uncontrolled, meaning it relies on the natural microbial communities present on the mustard seeds and the wrapping leaves . This increases the likelihood of product variations between batches, which is part of the artisanal character of the food.

Raw Materials

Black or brown mustard seeds (Brassia juncea or Brassica nigra)

Quantity: 200 grams. Fresh, high quality mustard seeds are essential.

Salt (sendha namak or common salt)

Quantity: 1 to 2 teaspoons, or to taste. Salt helps to control the fermentation by inhibiting undesirable microbes while allowing the desired halotolerant species to thrive.

Specific plant leaves

Quantity: Several large leaves. The type of leaf used varies by tradition. Options include banana leaves, turmeric leaves, or the leaves of the Khorisa plant (a wild relative of ginger). The leaves impart flavor and may contribute their own surface microbes to the fermentation.

Water

Quantity: As needed for grinding.

Optional additions

Crushed garlic, ginger, green chilies, or dried fish may be added to create regional or family specific variations.

Equipment

A traditional grinding stone (sil pata) or a heavy granite mortar and pestle

Used for grinding the mustard seeds into a smooth paste. A food processor can be used for convenience, but traditional stone grinding is believed to produce a superior texture and flavor.

Banana leaves or food grade plastic wrap

For wrapping the mustard paste to create an anaerobic environment that favors fermentation.

A clean glass jar or earthenware pot

For holding the wrapped paste during fermentation.

A weight or heavy object

Used to press the wrapped paste, ensuring even fermentation and proper texture.

Step by Step Recipe for Chakapura

1. Prepare the mustard seeds

Wash the mustard seeds thoroughly and drain them. Spread them on a clean cloth and allow them to air dry completely. The seeds should be dry before grinding to prevent premature clumping.

2. Grind the mustard seeds

If using a traditional grinding stone, add the mustard seeds to the stone and grind them with a circular motion, adding small amounts of water as needed, until a smooth, slightly coarse paste forms. If using a food processor, pulse the seeds with a small amount of water until a paste forms. Do not over process, or the paste may become too oily.

3. Add salt and optional ingredients

Transfer the mustard paste to a clean bowl. Add salt to taste. If using garlic, ginger, chilies, or other flavorings, grind them separately and mix them into the mustard paste.

4. Shape the paste

Take portions of the mustard paste and form them into flat patties or elongated rolls, approximately 5 to 7 cm in length and 1 to 2 cm in thickness.

5. Wrap the paste

If using banana leaves, pass the leaves briefly over an open flame to make them pliable. Cut the leaves into squares large enough to enclose the mustard patties completely. Place each patty on a leaf square and wrap it securely. Traditionally, the wrapped packages are tied with strips of the leaf or with kitchen twine.

6. Arrange for fermentation

Place the wrapped mustard packages in a clean glass jar or earthenware pot. Press them down gently to remove air pockets. Place a weight on top to keep the packages submerged in the liquid that will be released during fermentation.

7. Ferment

Cover the jar with a loose fitting lid or a breathable cloth secured with a rubber band. Place the jar in a cool, dark place with a consistent temperature between 20 and 30 degrees Celsius (68 and 86 degrees Fahrenheit). Allow the paste to ferment for 3 to 7 days .

8. Monitor the fermentation

Check the packages every few days. The mustard paste will release liquid, and the aroma will gradually shift from sharp and pungent to complex and tangy. The paste may develop a slightly grey or brownish tint on the surface; this is normal. Any appearance of fuzzy mold of green, black, or blue color indicates contamination, and the batch should be discarded.

9. Check for readiness

After 5 to 7 days, unwrap one package and taste the paste. Properly fermented Chakapura has a pungent, tangy, and savory flavor with a soft, spreadable texture. The initial sharp heat of the mustard should be mellowed by the fermentation, replaced by a more rounded, umami rich profile. The paste should have a pleasant, fermented aroma without any off putting smells.

10. Store

If the Chakapura is not consumed immediately, transfer the unwrapped paste to a clean glass jar. Press a piece of plastic wrap directly onto the surface of the paste to prevent air exposure, then seal the jar with an airtight lid. Store in the refrigerator, where it will keep for several months. The paste can also be left in its leaf wrappers and stored in a cool place for extended preservation.

Signs of Success

A properly made Chakapura has a soft, spreadable paste like consistency. The color ranges from yellow brown to grey brown. The aroma is pungent, tangy, and complex, with notes of fermented mustard and the specific leaf used for wrapping. The taste is savory, umami rich, and moderately pungent, with the sharp heat of raw mustard significantly reduced. The paste should be free of any off odors, bitterness, or visible mold.

Storage and Shelf Life

Properly fermented Chakapura stored in a sealed glass jar in the refrigerator will maintain its best quality for 2 to 4 months. Over time, the flavor may intensify and the color may darken. If stored at room temperature, the fermentation will continue, and the product will become increasingly sour and may eventually spoil. For longest shelf life, keep refrigerated. If any signs of mold, off odors, or slimy texture appear, discard the entire batch.

Troubleshooting Common Issues

Mold growth on the surface

Cause: Contamination by airborne mold spores, insufficient salt, or inadequate anaerobic conditions. Solution: Discard the affected portions or the entire batch. In future batches, ensure that the mustard paste is fully wrapped and that the jar is clean. Increasing the salt slightly may also help.

No fermentation activity (paste remains sharp and raw)

Cause: The temperature is too low for microbial activity, or the mustard seeds were treated with preservatives that inhibit fermentation. Solution: Move the jar to a warmer location between 25 and 30 degrees Celsius. Use organic mustard seeds from a reliable source.

Unpleasant or putrid smell

Cause: Contamination by undesirable bacteria. Solution: Discard the batch immediately. Ensure that all equipment is thoroughly sterilized and that the mustard paste was properly wrapped to create an anaerobic environment.

Paste becomes too dry or hard

Cause: Insufficient moisture in the mustard paste or inadequate sealing of the leaf wrappers. Solution: Add slightly more water when grinding the mustard seeds in the next batch. Ensure that the leaf wrappers are tightly sealed.

Bitter taste

Cause: Over fermentation or the use of poor quality mustard seeds. Solution: Reduce the fermentation time in future batches. Use fresh, high quality mustard seeds.

Functional and Clinical Benefits

Chakapura, like other fermented mustard products, offers several potential health benefits based on its microbial composition and bioactive metabolites.

Gut Health Support from Bacillus Probiotics

The dominance of Bacillus species in Chakapura is significant from a probiotic perspective. Bacillus species are spore forming bacteria, meaning they produce highly resilient endospores that can survive the acidic environment of the stomach, passage through the small intestine, and even the heat of cooking . Once in the large intestine, these spores can germinate into vegetative cells that provide probiotic benefits, including the production of enzymes, the inhibition of pathogenic bacteria, and the modulation of the gut microbial community.

Digestive Enzyme Production

Bacillus species are known for their robust enzyme producing capabilities. During fermentation, these bacteria produce proteases that break down proteins, amylases that break down starches, and lipases that break down fats. Consuming Chakapura introduces these enzymes into the digestive tract, potentially aiding in the digestion of other foods consumed in the same meal.

Anticancer Potential

The presence of indole 3 carbinol and sinapine in fermented mustard products suggests potential chemopreventive properties . Indole 3 carbinol has been extensively studied for its ability to modulate estrogen metabolism and induce apoptosis in various cancer cell lines . While these compounds are present in raw mustard seeds as well, fermentation may enhance their bioavailability.

Anti Inflammatory Properties

Gamma linolenic acid (GLA) and beta sitosterol acetate both have documented anti inflammatory effects . Regular consumption of small amounts of fermented mustard paste may contribute to the management of low grade chronic inflammation, though more research is needed.

Cardiovascular Health

Beta sitosterol acetate has been shown to lower cholesterol levels by competing with dietary cholesterol for absorption in the intestine . The fiber and phytosterol content of mustard seeds may also contribute to cardiovascular benefits.

Antimicrobial Activity

The organic acids and other bioactive compounds produced during fermentation create an environment that inhibits many foodborne pathogens. Historically, fermented condiments like Chakapura were valued for their preservative properties, allowing them to be stored without refrigeration and potentially contributing to food safety when consumed alongside other dishes.

Usage Note

Chakapura is a potent condiment and should be consumed in small quantities, typically 1 to 2 teaspoons per serving. It is traditionally eaten as a side dish with rice, dal, and vegetables, or used as a flavoring agent in curries and stir fries. The paste can also be spread on bread or mixed into salad dressings for a pungent, probiotic kick.

Individuals with histamine intolerance, mustard allergies, or compromised immune systems should consult a healthcare provider before consuming Chakapura. The product is naturally high in sodium due to the salt added during preparation. Those on sodium restricted diets should consume it sparingly. The fermentation process reduces but does not eliminate the pungent compounds in mustard; those with sensitive digestive systems may find the product irritating if consumed in excess.

The product is also a source of erucic acid. While the small quantities typically consumed are not considered a health concern, individuals with specific metabolic conditions may wish to consult their healthcare provider.

Chakapura represents a unique intersection of traditional food preservation, probiotic microbiology, and ethnobotanical knowledge. As scientific research continues to uncover the complex microbial and chemical profiles of these traditional ferments, their value as functional foods and as models for controlled fermentation systems becomes increasingly apparent.

x x x