Explain sun drying of foods with its advantages and disadvantages.

1. 1 · Open in two lines. Sun drying is the oldest method of preservation: food is spread in the sun so heat and moving air remove water until microbes cannot grow.
2. 2 · Principle. Water activity falls and enzymes slow; drying passes through a constant-rate and a falling-rate period.
3. 3 · Pre-treatments.
   • Wash, peel, slice thin.
   • Blanch vegetables; sulphur or KMS dip for light-coloured fruits.
   • Salt or buttermilk soak (mor milagai); alkaline oil dip for grapes.
4. 4 · Indian products. Vadam, papad, mor milagai, red chillies, turmeric, amchur, raisins, dry fish.
5. 5 · Draw the drying curve. [Graph: moisture against time, showing the constant-rate and falling-rate periods]
6. 6 · Advantages and disadvantages.
   • Cheap, no fuel, simple, large quantities, rural income.
   • Weather-dependent, slow, dust, insects, birds, vitamin loss, needs space, uneven.
7. 7 · Nutrition link. Shade or solar drying keeps more carotene; dried leaf powders enrich supplementary foods.
8. 8 · Close in one line. Solar dryers keep the low cost of sun drying while cutting its hygiene and vitamin losses.

Scoring tip: Two columns of advantages and disadvantages plus four Indian products make a strong answer.