**3.4 Cereal and legume-based fermented foods**

Cereal and legume-based fermented foods are regarded as staple foods in their respective provinces. They are a major source of economical dietary energy and nutrients throughout the world. In Indian subcontinent, region-specific cereals or legumes are subjected to natural or controlled fermentation to obtain desirable end products through the involvement of desirable microorganisms, mainly LAB, yeasts, and fungi, and have been well documented [84–86], and these organisms have the ability to increase palatability, maintaining the quality, safety, and nutritional value of the raw materials. The successive phase of growth of microorganisms in the fermentation of cereals and legumes also favors the growth of yeasts, which often occurs as a component of mixed microflora and gives specific characteristics to the product [87].

Most foods such as *idli, dosa, dhokla, khadi, Punjabi warri, adai dosa, kallappam, ambali* or *pazhaiya soru, koozhu, nan,* and *parotta* are routine food products of the native population. For the preparation of this type of fermented food products, chiefly use cereals such as rice (*Oryza sativum*), wheat (*Triticum* spp.), ragi (*Eleusine coracana*), barley (*Hordeum vulgare*), whereas pulses include black gram, green gram, and red gram. These cereals and legumes are cultivated in India since the Indus valley civilization period, that is, 9000–5500 BC [88], and are commonly used as main components in the preparation of significant amounts of food products. They are one of the effective substrates for the preparation of functional foods combined with probiotics. Since these products are rich in non-digestible carbohydrates, which help in the growth of Lactobacilli and Bifidobacteria. They consist of water-soluble fibers such as β-glucan, galactooligosaccharides, fructooligosaccharides, and arabinoxylan, and these fibers can be digested by selective LAB strains [89].

In the preparation of fermented foods such as *idli, dosa, adai dosa, kallappam,* and *dhokla,* the batter is prepared from the basic ingredients such as milled rice (*Oryza sativus*) and dehulled Black gram (Phaseolus mungo), and left the batter to ferment overnight at room temperature. For this, sodium bicarbonate can be added to create anaerobic conditions for LAB and yeast growth. In case of *Kallappam* preparation, the batter can be supplemented with fermented toddy to provide the extra LAB source. Leuconostoc mesenteroides are the most commonly encountered bacterium [90]. *Lactobacillus* plantarum AS1 isolated from fermented food from Southern Indian *Kallappam* successfully prevented colonization of entero-virulent bacterium Vibrio parahaemolyticus in HT-29 cell line and colorectal cancer in male Wistar rats [91, 92].

Preparation of *Pazhaiya soru* or *ambali* (Fermented rice) involves adding water to the cooked rice and later incubating the mixture overnight. Before consuming buttermilk add salt directly [20]. In most parts of south India, farmers consume this as an early morning meal before heading to the farm-field. Major microbiota isolated from this type of food include *Lactobacillus plantarum, Lactobacillus fermentum, Leuconostoc mesenteroides*, *Pediococcus cerevisiae,* Pediococcus acidilactici*,* Enterococcus faecalis*,* and Weissella paramesenteroides*.*

*Koozhu* is a traditional South Indian fermented food, a type of porridge made from finger millet and claimed to be a nutritious food. It is included in the daily diet of rural agricultural workers and urban households [93]. It is also given to children at weaning age [94]. It is made from Kezhvaragu or Cumbu flour and broken rice in a clay pot. *Koozhu* is easily digested and cools the body; therefore, during the summer, street vendors sell it as a cool drink in Southern India. There is an increase in thiamine, riboflavin, and niacin contents during its fermentation [95, 96].

In India, there are a large proportion of traditional fermented foods that are still unexplored for the microbiota and therapeutic values. Most of the research work has been done on the following fermented food products.

#### *3.4.1 Idli*

Among the closely related types of traditional fermented foods based on the combination of cereal and legume is the *idli*. It is a white, fermented (acid-fermented), steamed product with a soft and spongy texture, more popular and consumed throughout Southern India. It has been documented that *idli* batter fermentation has been in use since 1100 AD [97]. It is the resulting product of naturally fermented batter made from washed and soaked milled rice (*Oryza sativus*) and dehulled Black gram (Phaseolus mungo). From a nutritional and health point of view, *idli* seems to be an ideal human food for all ages of people and at all times. Investigations into the primary aspects of *idli* batter fermentation were started as early as in 1955 at the Central Food Technological Research Institute, Mysore, India. Several researchers have used different proportions of Black gram cotyledons to rice ranging from 4:1 to 1:4 weight to weight (w/w) for making *idli* with a preference for 2:1 and 3:1 over 4:1 [77, 98–101].

Studies have demonstrated the optimum fermentation conditions for obtaining good *idli*s as well as the physiochemical and microbiological changes that occur during intermittent periods of incubation at varying temperatures [98, 102, 103]. Typically, the microorganisms that develop during the initial and subsequent soaking of the ingredients are sufficient to cause fermentation. The microbiological changes during the fermentation period have shown the involvement of different genera and species of LAB and yeasts. The main bacterial floras identified include *Lactobacillus* brevis*,* Leu*conostoc mesenteroides, Lactobacillus* delbrueckii, *Lactobacillus* lactis*, Lb.* 

*Indian Traditional Fermented Foods: The Role of Lactic Acid Bacteria DOI: http://dx.doi.org/10.5772/intechopen.110741*

*fermentum, Pediococcus cerevisiae,* and Str*eptococcus* faecalis, while the yeast flora comprised Torulopsis holmii*,* Torulopsis candida*, Candida kefyr, Candida cacaoi,* Can*dida* tropicalis*, Candida fragicola,* Hansenula anomala*,* and *Puccinia* graminis. Moreover, these studies have shown the presence of major microflora at different stages of *idli* fermentation [101, 102, 104–108].

Two important changes that occur during *idli* fermentation are acidification and the leavening of the batter. Comprehensive studies on the various changes that accompany *idli* batter fermentation have shown that in addition to a consistent increase in microbial populations, the pH dropped to 4.4–4.9 from an initial pH of 6.6 [102, 106]. Several attempts have been made to improve holding *idli* fermentation by standardizing various physicochemical factors. An increase in the fermentation rate of *idli* batter was observed to accompany a rise in temperature [98]. Fortification of *idli* batter with glucose at 1% level has shown a beneficial effect on the gas formation and leavening during fermentation [109]. Similarly, the relationship between microflora type and biochemical traits revealed an increase in the content of water-soluble group B vitamins during *idli* fermentation [110].

As a step toward convenience in preparation, the dry mix concept was proposed as early as in 1960 [98]. In a similar approach, a process related to an improved means of providing inoculum (LAB and yeast) in ready-to-use form *idli* fermentation was developed [111]. In order to reduce the fermentation time of *idli* batter and increase its shelf life of fermented *idli* batter, an Indian patent has been filed [112]. Simultaneously, the flavor profile of such controlled fermented *idli* batter has shown the presence of desirable flavor compounds such as ketones, diols, and acids for an 8-day storage period. This flavor profile can be a reliable qualitative and quantitative parameter for objective evaluation [113].

Plantaricin LP84, a bacteriocin produced by *Lactobacillus* planatrum NCIM 2084, was able to retard the growth of foodborne pathogens such as *Bacillus cereus* F 4810, *Escherichia coli* D 21, and Staph*ylococcus* aureus FRI 722 during *idli* batter fermentation [114]. Fermented *idli* is easy to digest and is often used as baby food. This is the prescribed diet in hospitals for patients undergoing treatment (**Figure 6**) [85].

#### *3.4.2 Dosa*

*Dosa* is a fermented, thin, crispy, baked, and pancake-like product widely consumed in southern and parts of western India. In recent years, *dosa* has become more

**Figure 6.** *Idli and batter (courtesy: Sharmis passions, Hebbars kitchen).*

**Figure 7.** *Dosa (courtesy: Madhura's recipe).*

prominent throughout India including in Indian restaurants around the world. The *dosa* batter preparation is nearly similar to the *idli* batter, except for the proportion of milled rice and Black gram dhal usage. In the preparation of *dosa* batter, an equal quantity of milled rice and dehulled black gram dhal is soaked in water for a period of 6–8 h at room temperature (25–30°C) and grinded into a fine paste using the required amount of water, that is, 2.0–2.5 parts by weight. Later allow the batter to undergo natural fermentation for a period of 10–12 h at room temperature (25–30°C). From this fermented batter, *dosa* can be made like thin, crispy, pancake-type product.

Even in fermented *dosa* batter also numerous biochemical changes occur due to the effect of lactic acid bacteria along with yeasts [115, 116]. The predominant species identified were *Leuconostoc mesenteroides, Lactobacillus fermentum, Lactobacillus delbrueckii, Pediococcus cerevisiae, Saccharomyces cerevisiae*, *Hansenula anomala*, and *Kluyveromyces* sp. Typically, these microorganisms come from raw materials such as rice and Black gram [106]. *Dosa* batter fermentation also resulted in increased biochemical attributes, including that of water-soluble group B vitamins such as thiamine, riboflavin, and cyanocobalamin.

Attempts have been made to prepare products similar to *dosa* by replacing Black gram with other legumes like soy beans. Soy bean-based *dosa* batter was found to be nutritious but less preferred organoleptically (**Figure 7**) [117].

## *3.4.3 Dhokla*

*Dhokla* is one of the famous steamed food products in the western part of India, especially in Gujarat and Maharashtra States. It is prepared with a mixture of Bengal gram (Cicer arietinum), dehulled black gram (Phaseolus mungo), and milled rice (Oryza sativa) in a ratio of 2:1:1. This composition gives the product a soft and spongy texture. The above-mentioned mixture of grains is soaked in water for 6 to 8 h and ground to a granular consistency. To the resultant batter, the curd is added to a proportion of 1:1.5 w/w, after which it is allowed to ferment for 16 to 18 h and then steamed the product. Usually, this product is consumed by seasoning with oil, spices, and coriander leaves for taste [85, 97].

Research studies have shown that the numbers of LAB and yeast cells are increased during the fermentation process. Major microorganisms such as *Lactobacillus fermentum*, *Leuconostoc mesenteroides*, and *Han. Silvicola* are present in this product, whereas biochemical changes such as pH, acidity, and volatile fatty acid content in the food product are also documented as influencing the increase in microbial counts [118].

*Indian Traditional Fermented Foods: The Role of Lactic Acid Bacteria DOI: http://dx.doi.org/10.5772/intechopen.110741*

**Figure 8.** *Dhokla (courtesy: Ram Asrey).*

One more study found that *dhokla* batter was prepared using *Lactobacillus* species that exhibited antibacterial activity against harmful microorganisms such as B*acillus* subtilis*,* Bac*illus* licheniformis, and B*revib*ac*illus* laterosporus present as contaminants before processing. But in another study, it was reported that the same harmful bacterial species grew well in the *dhokla* batter that was prepared using *Lactococcus* species due to a lack of antibacterial activity [119, 120]. These results indicate that those LAB have an antagonistic nature and are able to provide healthy food products in terms of safety (**Figure 8**).

#### *3.4.4 Kadhi*

It is a traditional fermented food, prepared by boiling lactic fermented and agitated *dahi* with 5 to 8% (w/w) Bengal gram flour, that is, besan flour as a thickening agent. It is consumed in most parts of India as a cooked food that has a slightly sour taste and gives it a classic baked flavor. Considering the potential use of antagonistic LAB, studies have been carried out to evaluate the effectiveness of the antibacterial properties of selected LAB for foodborne pathogenic and spoilage bacterial species occurring in pre-processing and post-processing contaminants in *kadhi*. The study highlighted the benefits of using pure cultures of LAB with antagonistic nature such as *Lactobacillus delbrueckii* ssp. *lactis* CFR 2023 and *Lactobacillus* delbrueckii ssp. *bulgaricus* CFR 2028 in *kadhi* preparation with desirable quality attributes and preservation against foodborne pathogens [63, 120].

LAB isolated from *khadi* showed antibacterial activity against S*taphylococcus* aureus, Escherichia coli*,* and P*seudomonas* aeruginosa as well as exhibited probiotic properties [121]. The effectiveness of antagonistic cultures of *Lactobacillus* species was evaluated in terms of microbiological and sensory parameters in *kadhi* during storage at ambient and refrigerated temperatures [119]. Research studies have attempted to modify the *kadhi* preparation to provide better nutritional status through the use of smaller quantities of Bengal gram flour obtained from pre-soaked seeds. Based on the sensory attributes and the characteristic consistency of *kadhi*, the product prepared using Bengal gram flour (from pre-soaked seeds at 40 mg/g) showed better acceptance compared to the product prepared by a conventional method using 100 mg/g of besan (**Figure 9**) [56].

#### *3.4.5 Punjabi warri*

It is a pulse-based dried product, commonly prepared in north India. They are spicy, hollow, crunchy, small fried balls and used as a condiment in cooking with vegetables, soups, or Indian sambhar (dhal-based spicy liquid). It is prepared using dehulled black gram (Phaseolus mungo), which needs to be soaked overnight in water

**Figure 9.** *Kadhi (courtesy: We recipes).*

and then ground into a soft batter. Different types of spices are added to this batter and made into small balls. After this allowed to ferment for a few hours and dried in an open space for 4 to 10 days [122].

Microbiological and biochemical aspects associated with Punjabi warri have been studied in some research investigations [106, 122]. These studies have established that the development and prevalence of microorganisms were affected by the seasons; summers are more favorable for bacteria and winters for yeasts. These microbial types tend to increase significantly as fermentation progresses. The microorganisms that are responsible for the fermentation of this product mainly include Leu*conostoc* mesenteroides*, Lactobacillus* fermentum, Str*eptococcus* faecalis, *Saccharomyces cerevisiae*, Pichia membranaefaciens*,* and *Trichosporon beigelii*. During this process, there is an increase in enzyme activity such as amylase and other proteinase, which leads to the enhancement of water-soluble B-vitamins such as thiamine, riboflavin, and cyanocobalamin. These biological changes influence the nutritional quality of food products.

Some research studies have shown that the use of *Lactobacillus* delbrueckii ssp. *bulgaricus* CFR 2028 and *Lactobacillus* delbrueckii ssp. *lactis* CFR 2023 in warri preparations exhibited antibacterial activity against food-borne pathogens like B*revib*ac*illus* laterosporus*,* Bac*illus* licheniformis, and *Bacillus subtilis*. The preparation of this product involves combined fermentation and drying processes where *Lactobacillus* species act as biopreservative. Hence, pathogenic microbial growth was stopped while the storage period of 10 days at room temperature [119, 120].

In addition to the above, there are several other documented cereal and legumebased traditional foods popular in specific regions of India. However, detailed scientific and technological studies have not been much documented on these foods.

#### **3.5 Milk and cereal/legume-based fermented foods**

#### *3.5.1 Rabadi*

*Rabadi* is a fermented drink most commonly used in the Rajasthan province of India. It is made from a combination of pearl millet flour (Pennisetum typhoideum) or wheat flour and buttermilk, using an earthenware vessel as a container and then keeping it for natural fermentation for 4 to 6 h at room temperature. This is followed by dilution of the product with water, cooking, and adding salt to taste. This process improves the level of LAB that can be served as health drinks [123].

*Rabadi* fermentation of freshly ground wheat millet flour brought about a significant increase in the HCl-extraction capacity of calcium, iron, copper, zinc, manganese, and
