Agriculture Reference
In-Depth Information
the bunch emerged. The maturity is checked by determining the caliper of the
middle fi nger of the outer whorl of the second hand. When the caliper reading
is between 31 and 41 mm in diameter, the bunch is ready to harvest. If the
caliper reading is less than the 31-41 mm minimum, the fi nger is rechecked
the next week, and if after the week the caliper is still too small, the bunch
will be harvested and fruit sent to the local market. In this way, over-aged
fruit are not exported. If over-aged fruit are included in export fruit shipment,
it is possible that they will start to ripen in transit and induce ripening of the
whole shipment.
Small growers tend to harvest bunches when more than three-quarters
mature with little angularity and at fully rounded stage. More mature fruit
have a shorter postharvest life and are more liable to be sunburnt and split.
Other criteria used to judge maturity include drying of leaves, drying of stylar
ends and days from bunch emergence. The days from bunch emergence can
vary from 7 to 24 weeks, depending upon cultivar, season, crop management
and environment. Other measures include pulp to peel ratio and skin fi rmness.
The bunch is removed from the plant by cutting a notch in the pseudostem
while supporting the bunch with a pole and slowly lowering it on to the
shoulder pad of a harvester. The stem is then fully cut, leaving a 300 mm
peduncle. The bunches are transported to the packing shed on padded trailers
or on an overhead cable system. Dehanding can be performed in the fi eld, with
the hands transported to the packing shed on padded trailers. Care is essential
in these steps to avoid any mechanical injury that would reduce fruit quality.
Plantains in the tropics are harvested for export about 11 weeks after
fl ower emergence, and colour ribbons are again used as a guide to establish
bunch age. Plantain maturity standards vary widely and lead to considerable
variation in product quality.
Postharvest treatments
Bunch covers are removed in the fi eld or after the bunches reach the covered
packing shed. Bunches must be protected from exposure to direct sunlight to
avoid sunburn injury during transportation and at the packing-shed holding
area. Hands are removed with a sharp, curved knife or curved chisel, leaving
part of the crown attached. The hands, irrespective of whether dehanding
takes place in the fi eld or in the packing shed, are placed in clean water to
remove dirt and latex exuding from the cut crown; this should last a minimum
of 20 min. Care is needed to avoid the build-up of fungal spores in the water of
the wash tank, by frequent changes and the use of chlorine.
The hands are removed from the tank and sometimes cut into clusters of
adjacent fi ngers, with defective fi ngers being removed. The clusters are placed
in trays that pass through a fungicide-treatment spray or dip on a conveyor.
The conveyor then passes the trays to a packing station, where weight
