PREPARATION OF EXTRUDED PRODUCTS

Extrusion is a process that combines several unit operation including mixing. kneading, shearing, heating, cooling shaping and forming. It involves compressing, and working raw material eg. Flours, starches, proteins, salt, sugar and other minor ingredients to form a semi solid mass under a variety of controlled conditions and then forcing it to pass through a restricted opening such as a shaped hole or slot at a predetermined rate.

Heat in applied directly by steam injection or indirectly through a heated barrel. The final process temperature in the cooking extruder can be high as 200°C but the time of exposure to heat is relatively short (10-60 seconds). The extrusion cooking is also called a high temperature short time (HTST) process.

Extruded products

Rice based extruded products include sevai, idiappam, murukku (chakli) rice based vadagam etc. Rice based noodles and noodles from fermented rice flour are popular in China, Japan and the orient.