Effect of nutraceuticals (beta-glucan concentrate, flaxseed lignan concentrate and gamma oryzanol concentrate) on nutritional, textural, pasting, thermal, structural and morphological properties of corn and rice flour blend based RTE extrudates

Extrudates of corn and rice flour blend was prepared by substituting with low and high levels of beta-glucan isolated from barley flour, lignans isolated from flaxseed and gamma oryzanol isolated from rice bran oil using response surface methodology. All the optimized extrudates were characterized for their nutritional, textural, pasting, thermal, structural (X-ray diffraction (XRD)) and morphological (scanning electron microscopy (SEM)) properties. After extrusion, the fortified optimized samples retained 82.67 and 90.83% of beta-glucan, 86.31 and 66.66% of lignans and 71.33 and 51.67% of gamma oryzanol at their respective low and high levels. An increase in the textural hardness was reported in fortified samples as compared to control. A decline in the pasting characteristics was observed with substitution with each isolate in the all the flour blends. There was an increase in the Tonset, Tendset and Tpeak and decrease in the enthalpy of optimized fortified samples. XRD analysis showed that crystallinity decreased with the addition of beta-glucan concentrate as well as oryzanol concentrate but increased with the addition of lignan concentrate. SEM showed thicker cell walls and compactness with addition of beta-glucan and lignan concentrate. A higher level of cellular degradation was observed in the samples substituted with gamma oryzanol concentrate at both levels.