Extrusion Processing of Rice-Based Breakfast Cereals Enhanced with Tocopherol from a Chinese Medical Plant

Brown rice flour was mixed with a Chinese medical plant (Euryale ferox Salisb.) and processed to make ready-to-eat breakfast cereals using twinscrew extrusion. Levels of 15 and 20% feed moisture in flour, and 200 and 250 rpm screw speed were set, and the physicochemical properties and content of alpha-, beta-, gamma-, and delta-tocopherols were determined. The data showed that 15% feed moisture gave a low bulk density and water absorption index but a high expansion ratio and water solubility index. High screw speed (250 rpm) produced a result similar to that of 15% feed moisture. A sample with 85% brown rice flour with 15% E. ferox Salisb. retained the highest content of alpha-, beta-, gamma-, and delta-tocopherols (125, 6, 78, and 9 (mu)g/g), respectively. The optimum extrusion conditions determined were 15% E. ferox Salisb. mixed with brown rice at 15% feed moisture and at 250 rpm screw speed.