Process optimization of pearl millet-based fermented beverage components using response surface methodology and...

The majority of millets are produced in India, particularly pearl millet, which is more nutritious than both wheat and rice. Native to India, the "north-western semi-arid region" produces rabadi, a natural dairy beverage made from cereal and fermented by lactic acid bacteria. The three components of rabadi viz. pearl millet, buttermilk and deionized water were optimized by using Design Expert software trial version13.0.12.0. Rabadi was processed by using the traditional technique i.e., the three components were mixed in sterile conditions and fermented for 4 h at 37 °C and then cooked for 7-8 min at high flame and finally boiled. Parameters such as pH, viscosity, ash, moisture, total solids, antioxidants, total phenols, tannins, suspension stability, titratable acidity, total sugars, and reducing sugars were analysed for all 16 runs predicted by the software. 6.83 g of pearl millet, 42.44 ml of buttermilk, and 50.72 ml of deionized water were predicted to be the best formulation of rabadi, when using the set goal of maximizing the antioxidants, total phenols and minimizing the tannins. FTIR analysis was also carried out, after the final concentration optimization, to confirm the presence of phenolic compounds, antioxidants, carbohydrates, proteins and fatty acids.