FRUIT AND VEGETABLES: FRUIT RIPENING
Diagram
Ripening that goes on, or ripening that stops at picking
Climacteric fruit
Ripening brings a rise in respiration and ethylene. The fruit keeps ripening after picking.
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Non-climacteric fruit
No rise in respiration and ethylene at ripening. The fruit does not ripen after picking, so it must be picked ripe.
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The key point
One keeps changing after harvest, the other only changes while still on the plant.
Figure 1: Climacteric fruits keep ripening after picking; non-climacteric fruits do not. Drawn in our own style from the fruit physiology and postharvest chapters of Sinha et al., Handbook of Fruits and Fruit Processing, and the ethylene and ripening discussion in Peter Scott, Physiology and Behaviour of Plants. Note: this source is chapter level, so the article states the distinction plainly and gives only the examples the books name.
Introduction
Climacteric and non-climacteric fruits both ripen, but they ripen in different ways. A climacteric fruit shows a rise in respiration and a rise in ethylene as it ripens, and it keeps ripening after it is picked. A non-climacteric fruit shows no such rise, and it does not ripen after picking, so it must be picked when it is already ripe. That difference decides when each fruit is harvested and how it is stored and ripened.
Sinha et al. cover fruit physiology and postharvest handling, and Scott covers ethylene and ripening fruits. The FTN Post-Harvest Technology notes, Unit 2, cover postharvest operations. This article follows those sources, and it states plainly where the source is chapter level rather than a head to head passage.
Quick comparison
Table 1: Climacteric fruits compared with non-climacteric fruits
| Aspect | Climacteric fruits | Non-climacteric fruits |
|---|---|---|
| Ripening after picking | Keeps ripening after picking | Does not ripen after picking |
| Respiration at ripening | Rises sharply, the climacteric rise | Stays steady, no rise |
| Ethylene at ripening | Rises sharply, and ethylene drives ripening | Stays low, and ethylene does not drive ripening |
| Harvest timing | Can be picked mature but unripe, and ripened later | Must be picked ripe, because no ripening follows |
| Examples | Banana, apple, mango, tomato, avocado, pear | Citrus fruits, grape, strawberry, pineapple, cherry |
| Starch change | Starch turns to sugar as the fruit ripens, as in banana | Little starch to turn to sugar, because the fruit is picked ripe |
| Softening | Softens as it ripens after picking | Softens little after picking |
| Storage | Can be stored unripe and ripened when wanted, with ethylene and temperature control | Must be kept cold to slow decay, because ripening cannot be managed after picking |
| Eating quality | Develops sweetness, aroma and colour after picking | Eating quality is fixed at picking, and only decay follows |
| Handling risk | Bruising and over ripening in storage and transport | Decay and water loss, because the fruit is already ripe at picking |
Scientific explanation
Definition
A climacteric fruit is a fruit that shows a sharp rise in respiration and in ethylene production as it ripens, and that keeps ripening after it is picked. A non-climacteric fruit is a fruit that shows no such rise in respiration and ethylene at ripening, and that does not ripen after it is picked. The terms describe the ripening pattern, not the species alone, and the books cover them in their fruit physiology and postharvest chapters.
Working principle
In a climacteric fruit, ripening starts a burst of respiration and a burst of ethylene, and the ethylene then drives more ripening, so starch turns to sugar, the flesh softens, colour changes and aroma develops, even after the fruit has left the tree. That is why a banana picked green turns yellow and sweet in the shop. In a non-climacteric fruit, there is no burst, and the fruit only ripens while it is still on the plant, drawing sugar and flavour from the plant. Once picked, it does not sweeten or soften further, and it only loses water and decays.
Apparatus
The books used here name no laboratory apparatus for telling the two apart, so no apparatus list is given.
Measurement procedure
The books used here name no single standard laboratory procedure for telling the two apart in one test. The distinction is made by following respiration and ethylene over time after picking: a rise marks a climacteric fruit, and no rise marks a non-climacteric fruit. The books give no worked food example with numbers for this comparison, so none is given.
Factors affecting readings
Temperature changes the speed of ripening in climacteric fruits, and cold slows it. Ethylene in the store can ripen climacteric fruits together. Maturity at picking decides how well a climacteric fruit ripens later, and a fruit picked too early never ripens well. For non-climacteric fruits, temperature and humidity decide how fast the picked ripe fruit decays.
Formulas and calculations
The books used here give no formula for this comparison, so no formula or worked calculation is given.
Industrial applications
- Climacteric fruits are picked mature and unripe, shipped firm, and ripened near the market.
- Non-climacteric fruits are picked ripe and shipped cold, because they cannot ripen later.
- Bananas are ripened with ethylene in ripening rooms before sale.
- Citrus fruits are picked ripe and kept cold to slow decay.
- Tomatoes, a climacteric fruit, are picked mature and green and ripened for sale.
Advantages and limitations
- Climacteric fruits: advantage: can be shipped firm and ripened when wanted. Limitation: can over ripen quickly in storage if ethylene and temperature are not controlled.
- Non-climacteric fruits: advantage: picked ripe, so eating quality is ready at harvest. Limitation: cannot be picked early to survive long transport, and decay starts at once.
- Climacteric fruits: advantage: ripening can be managed with temperature and ethylene. Limitation: a fruit picked too early never develops full flavour.
FAQ
Is a tomato climacteric?
Yes. Tomato is a climacteric fruit: it keeps ripening after picking, with a rise in respiration and ethylene.
Can a strawberry ripen after picking?
No. Strawberry is non-climacteric, so it does not ripen after picking and must be picked ripe.
Why are bananas picked green?
Banana is climacteric, so it can be picked mature and unripe, shipped firm, and ripened later.
What is the climacteric rise?
It is the sharp rise in respiration, with a rise in ethylene, that marks ripening in climacteric fruits.
References and further reading
- FTN Post-Harvest Technology notes, Unit 2 (postharvest operations).
- N. K. Sinha et al. (eds.), Handbook of Fruits and Fruit Processing, Wiley, 2012 (Google Books page read).
- Peter Scott, Physiology and Behaviour of Plants, Wiley, 2008 (Google Books page read).
