Optimization of extraction process of inulin from Indian millets (jowar, bajra and ragi)-characterization and cost analysis.

Prebiotic biomolecule, namely, inulin was extracted from Indian millets, namely, jowar (Sorghum vulgare), bajra (Pennisetum glaucum) and ragi (Eleusine coracana). Through qualitative assessment using Fourier Transform Infrared spectroscopy, the presence of functional groups of inulin in the above mentioned Indian millets were verified. The values of degree of polymerization of inulin derived from jowar, bajra and ragi were determined to be 27, 39 and 23 respectively. A comparative analysis of growth of Lactobacillus casei was carried out in presence of both lactose and inulin extracted from three millets and the commercial one. It was observed that the bajra inulin and lactose combination exhibited the best bacterial growth. The prebiotic effectiveness of different varieties of inulin was calculated to be in the following order: bajra > jowar > ragi > commercial inulin. Therefore the results on bajra inulin were highlighted in this article. Inulin yield from bajra was optimized as a function of temperature, HCl concentration and heating period. The maximum inulin yield (0.4727 g/g bajra) was obtained at temperature 70 °C, HCl concentration of 0.8 M and heating period of 60 min. The prebiotic activity score of bajra inulin (= 3.2) was measured to be much higher than commercial inulin (= 1.0). Growth dynamics of Lactobacillus casei on lactose, bajra inulin and mixture of lactose and bajra inulin were found to be of Monod type, Haldane type and Multi-substrate-summative type respectively. The techno-economic analysis based on the production cost of inulin from raw bajra seeds suggested that it was much cheaper than commercial inulin.