The Dominant Microbes in Dhokla Batter
The signature soft and spongy texture of dhokla is a direct result of fermentation, a process driven by a specific community of microbes. When the batter, typically a mixture of rice and Bengal gram (chickpea) flour, is left to rest, it undergoes a natural fermentation. The stars of this process are Lactic Acid Bacteria (LAB), along with certain yeasts.
Among the LAB, two species are prominently associated with dhokla fermentation:
- Lactobacillus fermentum: A key player in the process, this bacterium is responsible for producing lactic acid, which imparts the characteristic sour flavor to the dhokla.
- Leuconostoc mesenteroides: This bacterium is essential for producing the carbon dioxide gas that leavens the batter and gives it its soft, airy structure.
In addition to these bacteria, specific yeasts, such as Hansenula silvicola, also contribute to the batter's rise and overall quality. This dynamic combination of microbes works synergistically to create the perfect dhokla texture and flavor.
How Microbes Create Dhokla's Signature Texture and Flavor
During fermentation, the microorganisms in the dhokla batter break down the carbohydrates present in the rice and lentils. This metabolic activity leads to two main outcomes that define the final product:
- Acidity and Flavor: The LAB consume sugars and produce lactic acid. This lowers the batter's pH, which not only gives dhokla its characteristic tangy taste but also helps to inhibit the growth of unwanted, spoilage-causing microbes.
- Leavening and Sponginess: The production of carbon dioxide gas, primarily by Leuconostoc mesenteroides, causes the batter to rise and become light. When the batter is later steamed, the trapped gas expands, creating the network of tiny air pockets that result in dhokla's famously spongy texture.
Biochemical Changes and Antinutrients
The fermentation process does more than just affect taste and texture; it also significantly improves the nutritional profile of the dhokla.
- Reduction of Antinutrients: Antinutrients such as phytic acid and tannins, naturally present in the raw ingredients, are broken down during fermentation. This makes the nutrients more bioavailable for human absorption.
- Enriched Nutrients: The microbial activity can also increase the content of certain vitamins, such as B-group vitamins and folic acid.
The Dhokla Safety Check: Fermentation vs. Contaminants
While dhokla fermentation is driven by beneficial microbes, the raw ingredients can sometimes be contaminated with foodborne pathogens like Bacillus cereus, Staphylococcus aureus, and Escherichia coli.
- Pathogen Control: The drop in pH during fermentation is an effective measure against many pathogens. The acidic environment is hostile to most common spoilage and disease-causing bacteria, limiting their growth.
- The Critical Role of Steaming: However, fermentation alone is not enough to guarantee safety. The steaming process is the critical final step that heats the batter to a temperature sufficient to kill remaining harmful microorganisms and their heat-sensitive toxins. Steaming is particularly important for killing heat-resistant spores, such as those from B. cereus, ensuring the final product is microbiologically safe for consumption.
Fermented Dhokla vs. Instant Dhokla
| Feature | Traditional Fermented Dhokla | Instant (Fruit Salt/Baking Soda) Dhokla |
|---|---|---|
| Leavening Agent | Naturally occurring Lactic Acid Bacteria (LAB) and yeasts from the environment and ingredients. | Chemical agents like Eno fruit salt (citric acid + sodium bicarbonate) or baking soda. |
| Time Required | A long fermentation period, typically 8-12 hours or overnight. | Almost instantaneous reaction upon adding the leavening agent just before steaming. |
| Flavor Profile | A deeper, more complex tangy and slightly sour taste due to lactic acid production. | A milder, less complex flavor, sometimes described as slightly bitter if too much baking soda is used. |
| Probiotic Content | Rich in beneficial probiotics that promote gut health, as they are a result of live culture fermentation. | Lacks probiotic content since chemical leavening agents are used and fermentation is skipped. |
| Nutritional Profile | Enhanced nutrient bioavailability (e.g., B-vitamins) and reduced antinutrients through fermentation. | Less nutritional enhancement compared to the fermented version, as the natural breakdown of antinutrients is bypassed. |
Conclusion
In conclusion, the answer to which bacteria is present in dhokla is a complex microbial symphony dominated by Lactic Acid Bacteria, particularly Lactobacillus fermentum and Leuconostoc mesenteroides, with yeasts also playing a supportive role. This natural process of fermentation is fundamental to creating dhokla's unique flavor, light texture, and enhanced nutritional benefits, including its probiotic properties. The fermentation also serves as an important first step in microbial safety by lowering the pH, but the final, and most crucial, safety step is steaming, which effectively eliminates remaining pathogens. Therefore, the perfect dhokla is a testament to the powerful and delicious collaboration between food ingredients and beneficial microorganisms. You can read more about the research behind dhokla's fermentation and nutritional value in this study: Preparation of antinutrients-reduced dhokla using response surface methodology.
