Last reviewed 1 Oct 2026 · 7 min read
Respiration of harvested produce
After harvest, fruits and vegetables continue to respire, using stored sugars and oxygen and releasing CO₂, water and heat:
Respiratory quotient (RQ) — about 1.0 for carbohydrate substrates, above 1 for organic acid oxidation, below 1 for fats (about 0.7), and rises sharply when fermentation (anaerobic) starts (CO₂ without O₂ use). Heat of respiration causes warming and is a major refrigeration load.
Rate and temperature (Q₁₀)
A fruit has a respiration rate of 40 mg CO₂/kg·h at 20 °C, with .
- At 10 °C: mg/kg·h.
- At 0 °C: mg/kg·h.
Cooling from 20 °C to 0 °C reduces respiration by a factor of and thus roughly extends the storage life by a similar factor (other deterioration also slows).
Climacteric vs non-climacteric produce
| Group | Behaviour | Examples |
|---|---|---|
| Climacteric | A sharp rise in respiration and ethylene at ripening (climacteric peak); can ripen after harvest | Apple, banana, mango, papaya, guava, tomato, avocado, pear, peach, plum, kiwifruit |
| Non-climacteric | No peak; respiration falls slowly; ripen only on the plant | Citrus, grape, pineapple, strawberry, cherry, watermelon, pomegranate, cucumber, capsicum |
Ethylene
Ethylene (C₂H₄) is a gaseous plant hormone that triggers and speeds ripening, senescence, yellowing, sprouting and abscission; climacteric fruits produce much more (e.g., ripe apples, bananas, avocados). Effects: ripening, softening, loss of green colour (leafy vegetables), russet spotting (lettuce), off-flavour (bitter in carrot), sprouting; accelerates decay.
Control of ethylene:
| Method | Details |
|---|---|
| Ventilation | Flushes the gas out |
| Ethylene scrubbers/absorbers | Potassium permanganate (on alumina/zeolite) oxidises ethylene; catalytic oxidisers, ozone or UV photocatalysis |
| Low temperature and low O₂ (CA) | Reduces production and action |
| 1-MCP (1-methylcyclopropene) | Blocks the ethylene receptors; used on apples and others (commercial, approved formulations) |
| Separate storage of ethylene producers and sensitive crops | Basic rule |
Ripening chambers
- Controlled ripening of banana, mango, papaya, tomato by ethylene gas (about 100–150 ppm, from a cylinder or generator) at 18–20 °C and 85–95 % RH, for about 24 h, followed by ventilation to remove CO₂ and ethylene; banana ripening takes about 4–6 days with an appropriate temperature profile.
- Ethephon (2-chloroethylphosphonic acid) releases ethylene when dissolved in water at the proper pH — used for fruit dips or sprays at regulated doses.
- Calcium carbide (acetylene) for ripening is banned under FSSAI regulations in India — it is unsafe (it can contain traces of arsenic and phosphorus, damaging health). Approved alternatives are ethylene or ethephon in prescribed ways (check the current regulations).