Formulation of prebiotic, low glycemic index millet soups using foxtail, barnyard and kodo millet

Abstract

Optimization of foxtail, barnyard, and kodo millet, was carried out to formulate millet soup mix by adopting a mixture design. The physico chemical parameters such as pH, Total Soluble Solids (TSS), viscosity, color values (L*, a*, b*), quality characteristics such as soluble, insoluble total fiber, reducing sugar, total phenolic content, and various sensory parameters such as appearance, colour, aroma, taste, and overall acceptability were recorded to assess the effect of selected above three millets on the reconstituted millet soups. Optimization was done and a polynomial model was developed using Response Surface Methodology (RSM) relating to total fiber, antioxidant activity, prebiotic activity score, glycemic index and overall acceptability of the millet soups. Results revealed that there was a significant difference (p < 0.05) observed in the in the pH, TSS, viscosity among ten variations of millet soups. Similar statistical significance (p < 0.05) was noticed in the colour values. Quality characters such as reducing sugar, insoluble, and soluble dietary fiber values were also found to be different between the ten millet soup variations. Highest value of total phenolic content was recorded in MS6 variation with 7.5 gm of barnyard and 7.5 gm kodo millet flour in the millet soup. The overlay plots were used to attain the optimum formulation for the millet soups related to total dietary fiber, antioxidant activity, prebiotic score, glycemic index and overall acceptability which created the yellow region based on the optimized value. The results revealed that the optimum values for the predicted responses were 5.65 g, 24.96%, 0.36, 41.85, 7.65 for the total dietary fiber, antioxidant activity, prebiotic score, glycemic index and overall acceptability, respectively, which was attained from the optimum mixture of 2.14 gm foxtail millet flour, 5.76 gm barnyard millet flour, and 7.11 gm kodo millet flour. From the results the optimized millet soup can be categorized as low glycemic soup (GI < 55) with good prebiotic activity.