Explain extrusion cooking and its applications.

1. 1 · Open in two lines. Extrusion cooking is an HTST process in which moist starchy or protein food is cooked by heat, pressure and shear in a screw barrel and forced through a die.
2. 2 · Draw the extruder. [Diagram: feed hopper → screw in heated barrel → die → cutter → puffed product]
3. 3 · Process.
   • Mix and feed.
   • The screw kneads and cooks; starch gelatinises.
   • The die shapes; the pressure drop puffs; a knife cuts.
   • Dry, coat and pack.
4. 4 · Products. Puffed snacks, breakfast cereals, soya chunks, fortified rice kernels, weaning mixes, pasta (cold extrusion).
5. 5 · Advantages and limits. Versatile, continuous, shelf-stable, destroys antinutrients; costly, lowers available lysine.
6. 6 · Nutrition link. Soya chunks and fortified rice kernels improve protein and micronutrient supply in Indian diets.
7. 7 · Close in one line. Extrusion turns cheap cereals and pulses into ready-to-eat, shelf-stable foods.

Scoring tip: A labelled extruder sketch plus three Indian products answers this well.