Agriculture Reference
In-Depth Information
the skin oxidizes as brown and black stains and can lead to downgrading
of fruit. Other concerns are diseases, particularly crown rot, which may
af ect the whole carton and promote uneven fruit ripening. Because of weak
pedicels, the fi ngers of some cultivars fall from the hand during ripening,
exposing the pulp.
Plantains have a tougher skin than bananas and so there is less danger
of causing harm to them by improper handling; in general they should be
treated the same way as bananas, but in most instances they use less elaborate
systems for harvest, transport to the packing house and packing than for
bananas.
Plantain boxes weigh 22.6 kg. Alternatively, green plantains are partially
ripened, peeled and frozen, with a heat treatment to minimize enzymatic
browning reactions.
Ripening
Dessert bananas are allowed to ripen and are chiefl y eaten raw when they
have low starch, high sugar and developed fl avour. Plantains have high starch
content and are eaten when green or ripe after boiling, frying or roasting. The
conversion of starch to sugar during ripening of plantain-type bananas is less
complete than in dessert bananas (Fig. 8.8).
The ripening process for the export dessert-type bananas is normally
carried out by specialists under controlled conditions just before distribution
and marketing to consumers. When bananas are allowed to ripen naturally,
it is dii cult to predict when fruit will be ready to eat. Under controlled
ripening conditions, ethylene is supplied from compressed gas cylinders,
ethylene generators or ethylene-generating chemicals, such as ethephon.
Commercially, bananas are treated with about 100 ppm ethylene for about
24 h under controlled temperature and humidity conditions and ventilation
to prevent carbon dioxide (CO
2
) build-up. Newer systems pressurize the
room to allow uniform ethylene distribution and temperature. Temperature
control allows fruit to be ripened on a specifi c schedule to colour stage 3 for
distribution in from 4 days at 19°C to 10 days at 14.5°C. The humidity control
has a signifi cant impact on the fi nal skin colour developed and fl esh softening.
In local markets, fruits are ripened by covering with a tarpaulin or cloth
after inserting a packet of calcium carbide (0.3 g/l) to generate acetylene.
Acetylene is a 100 times less ef ective analogue of ethylene. A prolifi c ethylene-
producing ripening fruit, such as avocado, can also be used as an ethylene
source, as can burning of incense sticks or young leaves of a number of trees,
such as gliricidia (
Gliricidia sepium
Stend) (Acedo and Bautista, 1991).
