Orange

Harvesting maturity:

The assessment of the readiness of citrus fruit for harvest presents some problems for small-scale producers because:
• citrus fruits do not ripen further after harvest. To reach their full flavour and
sweetness they must be left on the tree to ripen;
• in the tropics citrus often remain green when they are fully ripe internally
and do not develop an orange-yellow colour on the tree. The development
of the orange-yellow skin colour can be artificially induced after harvest (degreening).

These facts make it very difficult to assess harvest maturity just from the
appearance of the fruit on the tree. Small-scale producers marketing their own
fruit will be able to assess the readiness of their fruit on several counts, which will
vary in different situations, for example:
• Skin colour: where it develops normally, this will be a good guide to ripeness; if normal skin colour does not develop, maturity may be indicated by a change in the shade of green shown by the skin; lemons change from dark green to a silvery-green appearance at maturity;
• Size: experienced growers may evaluate maturity by considering size as well as with other characteristics, such as slight changes in skin colour; and
• Internal condition of fruit: if a few typical fruit thought to be mature are cut in two, they can be considered ripe if:
1. The juice has developed full flavour and is sweet;
2. The fruit pulp has developed to the normal colour; and
3. Juice drips from the half-fruit when the cut surface is held vertically.

Harvesting method.

Although the skin of citrus fruit is relatively tough and can
tolerate some degree of pressure, it is easily cut or punctured, providing access to
the serious post-harvest decay diseases: blue and green mould. Every care must be
taken to avoid cutting or puncturing the skin of citrus fruits at all times. Clippers or
secateurs should be used to remove the fruit from the tree. Fruit may be pulled by
hand, but there is danger that the stem may be pulled out of the fruit, damaging
the skin, or of damage to the tree providing an entry point for field diseases. Not
more than 0.5 cm of stem should be left attached to the fruit. If the fruit is mature
or ripe this piece of stem will dry up and fall off, leaving only the flower calyx
(button) attached to the fruit. As it is harvested, citrus fruit should be placed in
picking bags worn by the harvester or in plastic buckets.

Field handling. Harvested fruit is taken in the harvesting container either directly
to the packing facility or to the field assembly point, where it is emptied into field
containers. At either point the fruit should be protected from exposure to sunlight
and rain while awaiting packing or movement to the packing house.


Field handling.

Harvested fruit is taken in the harvesting container either directly
to the packing facility or to the field assembly point, where it is emptied into field
containers. At either point the fruit should be protected from exposure to sunlight
and rain while awaiting packing or movement to the packing house.


Post-harvest

Selection:
Before it is packed the fruit should be sorted to eliminate all foreign
material, such as leaves and twigs. The fruit is then inspected and pieces which are
unripe, immature, undersized, damaged or decaying should be discarded. The
extent to which superficial skin damage can be tolerated will depend upon the
market. Local consumers may be more concerned about the eating quality of
produce than its external appearance.

Size grading:
Where citrus fruits are to be pattern-packed in custom-made cardboard boxes it is usually an advantage to grading it into size categories. The differences between categories will depend on the type of fruit. Citrus sent to local markets in wooden crates will usually be size-graded by the retailer at the point of sale.

Packing. Citrus for sale in local and internal urban markets is packed in a variety of
containers. Baskets, wooden boxes, sacks, bags, factory-made wooden crates and
cardboard boxes are all used. Most citrus from large scale commercial production
are now packed in telescopic cardboard boxes. The recommended outside
dimensions for the boxes are 50x 30x 30 cm. These can be stacked eight boxes per
layer on standard 1 x 1.2 m pallets. The capacity of these boxes is about 18-20 kg.
Wooden crates can also be used for citrus provided they do not have sharp edges
or splinters which will damage the skin of the fruit. Wooden crates should not
exceed 25 kg capacity. Larger crates are difficult to handle and if dropped can
severely damage the contents. Citrus fruits can be packed a little above the top of
the box so that they are under slight pressure when the box is closed. This prevents
movement of fruit within the box during transport and handling and allows for
natural shrinkage.


Post-harvest treatments.

Citrus produced for local and other internal markets
should not require specific post-harvest treatments provided it is handled carefully
and packed properly. Commercially grown citrus for export is normally washed,
treated with fungicide and wax-coated on highly automated packing lines. There
may be occasions where citrus for internal urban markets requires fungicide
treatment. Where this is necessary, the fruit should be washed and dried after
sorting, then treated with fungicide and dried before packing. In those countries
where some types of citrus remain green when ripe it is not usually necessary to
de-green them for market. De-greening will only change the color of the skin of
citrus fruits. It will not ripen them internally. De-greening is carried out by
exposing the fruit to ethylene gas under controlled environmental conditions. It
can only add to the cost of the fruit to the consumer, without any compensation in
eating quality. However, we are aware that most consumers purchase with the
eyes, therefore yellow/orange color is preferable to the green one.

Experience has shown that it is the care taken with preparation of the fruit for shipping which very largely determines whether individual batches withstand the rigors of transport. Such preparation for shipping is carried out in packing houses. These include:


Post-ripening of green or unsatisfactorily colored fruit to achieve a salable peel color in ripening rooms.


Removal of dirt, sooty mold, spraying residues and scale insects in washers.


Finishing of oranges which do not develop the typical orange color, but instead remain pale gold, green or with green spots, in a dye bath at temperatures of 45 - 50°C. Fruit treated in this way must be marked accordingly with a stamp (color added).


Coating with a layer of wax and treatment with preservatives and marking accordingly.


Grading of the fruits by size (gaging), color and other external features.


Counting, weighing and packing. Marking each package with details of number of fruit, quality class, variety and origin.


Storage until shipment in cold stores.

Waxing to prevent loss of aroma and weight is required because the washing process removes the natural wax layer. The film of wax sprayed onto the peel only partially seals the pores so that the fruits are still able to respire.

Oranges are mainly transported in cartons, standard boxes, half-boxes, wire-bound boxes and fruit crates made of corrugated board or wood. They are sometimes also transported in net bag

Oranges are mainly transported in cartons, standard boxes, half-boxes, wire-bound boxes and fruit crates made of corrugated board or wood. They are sometimes also transported in net bags.


Citrus for sale in local and internal urban markets is packed in a variety of
containers. Baskets, wooden boxes, sacks, bags, factory-made wooden crates and
cardboard boxes are all used. Most citrus from large scale commercial production
are now packed in telescopic cardboard boxes. The recommended outside
dimensions for the boxes are 50x 30x 30 cm. These can be stacked eight boxes per
layer on standard 1 x 1.2 m pallets. The capacity of these boxes is about 18-20 kg.
Wooden crates can also be used for citrus provided they do not have sharp edges
or splinters which will damage the skin of the fruit. Wooden crates should not
exceed 25 kg capacity. Larger crates are difficult to handle and if dropped can
severely damage the contents. Citrus fruits can be packed a little above the top of
the box so that they are under slight pressure when the box is closed. This prevents
movement of fruit within the box during transport and handling and allows for
natural shrinkage.

Oranges are mainly transported in cartons, standard boxes, half-boxes, wire-bound boxes and fruit crates made of corrugated board or wood. They are sometimes also transported in net bags.