2021 Volume 27 Issue 2 Pages 211-219
Naked oat, rice and defatted flaxseed flour blends were extruded to prepare fresh extruded rice-shaped kernels (FER). Response surface methodology was adopted to evaluate influence of independent variables, that is, water feed rate (16–20 L/h) and zone 3 barrel temperature (90–110 °C) on the terminal product. Through results of the regression analysis, the predicted models were reasonable. Results showed that both the variables affected the responses studied, Overall, water feed rate was positively correlated with bulk density (BD) and hardness, whereas negatively with expansion ratio (ER), whereas temperature had the opposite relationship. FER with Run 5 (18 L/h, 124 °C) presented the lowest hardness (1 028 g) and Run 11 (18 L/h, 96 °C) the highest cohesiveness (0.767). FER with center points (18 L/h, 110 °C) had the highest lightness (50.70) and Run 4 (20 L/h, 100 °C) the highest retention rate of lignans (88.08%). The viscosity analysis showed that FER presented typical characteristics of extrudates, namely gelatinized starch. FER with Run 9 (21 L/h, 110 °C) presented the highest breakdown (586 cP), and Run 5 (18 L/h, 124 °C) presented the lowest setback (233 cP).
