Post-Harvest Technology and Value Addition
Domain 9 covers what happens between harvest and the consumer: maturity, respiration, handling, storage and processing into stable products.
Maturity and physiology
- Maturity indices: TSS, acidity, colour, firmness, days from flowering.
- Climacteric fruits ripen after harvest and respond to ethylene; non-climacteric fruits do not.
- Respiration and ethylene production drive perishability; cooling and controlled atmosphere slow both.
Handling and value addition
- Sorting, grading, prepackaging, cold storage, evaporatively cooled chambers.
- Products: jam (68-70 degrees Brix TSS), jelly (clear, from fruit extract), marmalade (with peel), squash and cordial, ketchup (25% TSS), pickle, dried and canned products.
- FSSAI standards and labelling apply to processed products.
Worked example
Deciding between jam and jelly from guava: guava is pectin-rich and acidic, so a clear extract sets into jelly; if the pulp is retained, the product is jam. Reasoning: jelly needs clarified juice, adequate pectin and acid at about pH 3.2-3.4, while jam uses crushed fruit. Both are preserved at 68-70 degrees Brix, which lowers water activity and checks microbial growth.
Marks-losing traps
- Using overripe fruit; pectin is already degraded.
- Calling any fruit product jam regardless of clarity.
- Storing climacteric fruit with ethylene-sensitive vegetables.
- Assuming squash needs only sugar, without acid or preservative.