Post-Harvest Management and Value Addition
Post-Harvest Management and Value Addition covers maturity indices, grading, storage and conversion of surplus produce into stable products.
Handling chain
Maturity indices vary by crop: mango on shoulder development and specific gravity, banana on angularity and peel colour, grape on TSS (16-18 Brix) and acid ratio, tomato on colour grade, onion on neck fall and dry skin. Harvest in the cool part of the day, avoid bruising, remove field heat, sort out diseased and injured fruit, grade by size and quality, pack in ventilated CFB boxes with liners. Low temperature slows respiration but every crop has a chilling threshold (banana and mango are injured below about 12 C). Controlled and modified atmosphere reduce oxygen and raise CO2. Ethylene or ethephon ripens banana and mango, while ventilation or potassium permanganate removes ethylene.
Value addition
Jam uses pulp with sugar to a final TSS near 68%; jelly uses clear fruit extract with acid and pectin; squash holds about 25% juice and 45% TSS with a permitted preservative; ketchup is tomato pulp with sugar, salt, vinegar and spices; pickle relies on salt and acid. Juice, RTS, chutney, dried and canned products extend shelf life. Labelling, date coding and FSSAI compliance belong in the answer.
Worked example. 100 L of mango squash at 25% juice needs 25 L of pulp. If pulp yield is 60% of fruit, fruit required = 25 / 0.60 = 42 kg. Reasoning: the juice percentage refers to the final product, not to the fruit; work back through the yield factor.
Traps that cost marks
- Storing banana at 4 C.
- Quoting jam TSS as 45%.
- Adding preservative before the sugar has dissolved.
- Treating ethylene as a disease rather than a ripening hormone.