Characterisation of Wheat–Oat Flour Extrudate: Physicochemical and Β-Glucan Attributes

Abstract

The objective of this study was to evaluate the effect of wheat–oat flour ratio on the physical properties and β-glucan characteristics of extrudates. Results showed that increasing the wheat–oat flour ratio resulted in a decrease in the water solubility index (r2=0.8567) and hardness (r2=0.9316), whereas the expansion ratio (r2=0.9307) and water absorption index (r2=0.9061) increased. Wheat flour generally caused an increase in L values from 57.81 to 62.94 providing bright samples. Few cells were observed at high wheat–oat flour ratios under a scanning electron microscope, and a smooth surface was noted. Meanwhile, the total (r2=0.9867) and soluble (r2=0.9848) β-glucan contents were inversely proportional to the wheat–oat flour ratio. Extrudates with added wheat flour had a high molecular weight, but wheat flour had no significant (P<0.05) effect on the viscosity of β-glucan extracts. Conclusively, incorporation of wheat flour at a wheat–oat flour ratio of 2.33 provides ready-to-eat food based on whole oat flour, on account of improving the texture and providing sufficient β-glucan contents (0.806 g/100 g) without significantly affecting β-glucan viscosity.