Post-Harvest Technology and Value Addition: Moisture, Milling and Storage
What this domain tests
Safe moisture levels, drying, cleaning and grading, rice milling and parboiling, storage, and small-scale value addition - plus the losses that occur when any step is skipped.
Core rules
- Safe storage moisture: paddy 12–14%, wheat 12%, jute fibre 8–10%. Grain above these levels heats and molds.
- Sequence: harvest at right maturity, thresh, clean, grade, dry, then store in clean, dry, fumigated bins or bags kept off the floor.
- Parboiling has three steps - soaking, steaming, drying - before milling; it gelatinises starch, reduces breakage and retains B vitamins.
- Cold storage holds potatoes at about 2–4°C; controlled-atmosphere stores cut respiration in fruits.
- Value addition in West Bengal: muri (puffed rice), chira (flaked rice), gur from date palm and sugarcane, potato chips, mango pickle, honey and jute handicrafts. Food businesses need FSSAI registration or licence.
Worked example
1,000 kg of paddy at 20% moisture is dried to a safe 14%. Dry matter is 800 kg and stays constant, so final weight = 800 ÷ 0.86 = 930 kg. Reasoning: solids do not evaporate; divide solids by the solid fraction of the target moisture.
Traps that cost marks
Confusing parboiling with milling; quoting 20% as safe moisture; drying in direct sun without a tarpaulin (cracking); storing bags against a damp wall.