The ripening process for bananas is typically as follows:
1) Green bananas in cartons or open crates are loaded into the ripening room (fruit pulp
temperature should not be lower than 14 ºC as lower temperatures can damage the
2) The room is closed and thermally controlled until the pulp temperature reaches 15-
17oC. This temperature is controlled and maintained by a thermostat. During summer
conditions or for direct field produce, a refrigeration system will cool the room to
maintain the set temperature and remove the heat of respiration.
3) Ethylene is supplied into the room at a concentration of around 100-400ppm (0.01 -
0.04%). The room is then kept closed for 24 hours. The ethylene acts as a catalyst
initiating the hormonal process of ripening.
4) At the end of this time the room is ventilated to clear the ethylene gas and the carbon
dioxide released due to increased respiration during the initial ripening phase.
5) The room temperature is controlled between 17oC to 15oC over three or four days.
The fruit pulp may reach a temperature of 32oC during this process and gases,
including carbon dioxide, are evolved in substantial quantities. Most of these gases
would normally be vented off by ripening room operators to maintain the carbon
dioxide level below 1%, as carbon dioxide levels above 7% inhibits further ripening.
6) The room is finally ventilated and the ripe fruit removed. A common way of
ventilating involves opening the doors for at least five, and usually fifteen, minutes
before entry is made. Extractor fans may also be used.
N.B. The amount of ethylene gas required for a ripening room is normally calculated on the
free air space after the bananas have been loaded (i.e. if bananas take up 35% of the room
size, the amount of ethylene required is calculated for the remaining 65% free air space.
Method of introducing ethylene gas
Ethylene generators which use a catalytic process to produce pure ethylene gas from a
solution containing mainly ethyl alcohol (ethanol) but which may have trace quantities of
other ingredients (e.g. methanol). The solution (sometimes known as 'ripening fluid') is
poured into a reservoir on the ethylene generator where it is slowly fed to an internal heater
which vaporises the ethanol which then passes to the catalytic converter. Each litre of
solution produces about 0.33-0.4 m3 of ethylene gas.
The hazards from this process fall into two main categories:
1) If the introduction of ethylene is uncontrolled there is a risk that the ethylene may
reach or exceed the lower explosive limit (LEL) of 3.1% and be ignited by
unprotected electrical apparatus or gas heating systems or other incendiary sources,
resulting in a fire or explosion.
2) Formation of flammable gas/air mixtures may result from spillage of ethanol-based
solution used in ethylene generators.
Toxicity and asphyxiation
There are also potential acute risks from oxygen depletion and from the accumulation of
other gases such as carbon dioxide; these health risks are exacerbated by the enclosed nature
of the process:
3) Oxygen deficiency in the room may result from excess addition of ethylene or
ethylene-nitrogen mixture from cylinders.
4) The evolution of carbon dioxide during the fruit ripening process may result in a toxic
or asphyxiating atmosphere. For example high levels of carbon dioxide may cause
loss of consciousness and death from respiratory failure. Other effects such as
headache and exhaustion occur at much lower exposure levels.
Ripening rooms (5 each) for Banana, Mango, Papaya
External RoomSize (Lx B x H) 7000 x 5000 x 4000 mm( 4 Nos.)
Roomtemperature &RH. 10 to 15 °C /90 to 95%
AmbientTemperature 2 °C (min) and45 °C (max)
ProductincomingTemperature 20 °C
ProductIncomingRate 10 MT per roomper batch
CoolingTime 24 Hrs
InsulationMaterial PUF panels,80 mm
Manual slidingdoor1500 mm x2100 mm PCGIboth
Type of condenser
Type of compressor
Total numberof units
1 x 40000 Btu/hr
1 nosper room
Outside nearthe chambers
Steamtype ,modulatingone foreachroom
Fan unit& damper
PowerRequirement 4 x 10 Kw,3 Ph, 415 V, 50 Hz
• Temperature dependence of the ripening process:
1. Too high: irregular ripening of the fruit / poor keeping quality (> 18°C)
2. Higher: rapid ripening / difficult to control
3. Lower: slower ripening / possibly slight taste degradation
4. Too low: chilling injury (< 12°C)
• Dependent on gas composition (O2 / CO2) – CO2 above 7% inhibits ripening.
The ripening process consists of the following steps:
o Bringing pulp between 15 to 17 ºC prior gassing.
• Gassing with Ethylene.
o Uniform Air Flow around produce.
o Uniform exposure to ethylene.
• Stepped or continuous temperature control.
o Temperature distribution inside the ripening chamber
o Temperature distribution within the pallets
o Temperature distribution within box
• Regular ventilation.
o Uniform Air Flow around produce.
o Controlled CO2 buildup.