Optimization of fermentation parameters and their impact on the final properties of the cereal-legume-based fermented product

The enhancement of food diversification through the utilization of underutilized crops is imperative at both national and household levels due to their inherent high nutritional value. Employing fermentation technology stands out as a promising approach for processing these crops at the household scale. Fermented foods exhibit attributes conducive to maintaining a healthy dietary regimen, as they are abundant in nutrients, cost-effective, easy to produce, and serve as potent sources of proteins and other essential dietary components for alleviating protein malnutrition, particularly in children. In the current study, experiments were conducted to standardise the process for formulating idli batter using blends of barnyard millet, black gram, and black soybean, employing fermentation technology. The experimental design followed the Box-Behnken approach, encompassing three levels of predicted variables: particle size (400, 500, and 600 μ), temperature (28, 32, and 36 °C), and fermentation time (8, 10, and 12 h). Various properties of the resultant idli batter influenced by fermentation parameters, including batter volume, pH, titratable acidity, and density, were meticulously examined. The observed batter volume ranged from 1 to 67 mL, pH from 5.7 to 4.58, titratable acidity from 0.36 to 0.67%, and density from 1.09 to 0.63 g/cm3. The optimal particle size of 400 μ, coupled with a fermentation temperature of 34.5 °C and a fermentation time of 12 h, yielded maximal expansion in batter volume, thereby contributing to the preparation of idli of superior quality. Additionally, the fermentation kinetics of the optimized batter were investigated to elucidate the growth patterns of microorganisms involved in the fermentation process. •The optimized ratio of barnyard millet, black soybean, and black gram was found to be 35:10:5.•Maximum batter volume was obtained at particle size of 400 µ, fermentation temperature and time of 34.5°C and12 h.•The fermentation kinetics of the optimized batter were investigated.