Explain tray and tunnel drying with their advantages and disadvantages.

1. 1 · Open in two lines. Tray and tunnel dryers dry pieces of fruits and vegetables with heated, moving air under control.
2. 2 · Tray (cabinet) dryer.
   • Insulated cabinet, stacked mesh trays, fan and heater; batch.
   • Cheap and flexible; uneven drying, labour needed.
3. 3 · Draw a tray dryer. [Sketch: fan → heater → air across stacked trays → exhaust]
4. 4 · Tunnel dryer.
   • Trolleys of trays move through a long hot-air tunnel; semi-continuous.
   • Co-current (gentle, higher final moisture) or counter-current (drier product, scorching risk).
5. 5 · Uses. Vegetable and fruit slices, leaves, dried vegetable mixes.
6. 6 · Nutrition link. Cleaner and faster than sun drying, so more vitamin C and carotene survive.
7. 7 · Close in one line. Tray dryers suit small units; tunnels suit large-scale drying.

Scoring tip: A small sketch of each dryer and the co-current vs counter-current point lift this answer.