Effects of Extrusion Cooking Over Roasting on Retention of Nutritional Quality of Composite Flour Prepared From Soyabean, Millet, Corn and Rice Blend

The objective of this study was to compare the effects of extrusion cooking and roasting on the nutritional composition of the blend obtained from rice, soybean, millet and corn flours. Two different flour compositions with different proportions of ingredients were prepared. Roasting process was conducted at 160°C for a duration of 30 minutes, whereas extrusion cooking was performed at 129°C for approximately 5 minutes. Chemical analysis was carried out on all four samples. The findings revealed that the moisture and carbohydrate content in the extrusion-cooked samples (A and B) were higher than in the roasted samples (A’ and B’). In contrast, crude fat content, crude fiber content, and ash contents were higher in roasted samples (A’ and B’) compared to extrusion-cooked samples (A and B). The protein content of samples A, A’, B and B’ was found to be 10.67%, 8.47%, 14.64% and 9.18%, respectively. This proven protein content is higher in extruded composite flours (A and B). Additionally, calcium and iron contents were higher in the roasted samples, with sample B’ having the highest calcium and iron contents. Tannin content and phytic acid content was also higher in the roasted samples, with sample B’ having the highest tannin and phytic acid content. In conclusion, extrusion cooking increased nutritional content while reducing anti-nutritional components in the composite flour, suggesting its potential as a preferred processing method to maintain nutritional quality.