Coconuts
| Infobox on Coconuts | |
|---|---|
| Example of Coconuts |  |
| Facts | |
| Origin | - |
| Stowage factor (in m3/t) | - |
| Humidity / moisture |
|
| Ventilation | - |
| Risk factors | - |
Coconuts
Description
Postharvest cooling, handling and storage of (fresh) Coconuts
| Freshness facts | |
| Optimum carrying temperature | 0°C to 1,5°C (see text) |
| Highest freezing point | -0,9°C |
| Acceptable products temperature at loading
into container |
Max. 2°C above carrying temperature |
| Optimum humidity | 75% to 85% |
| Ventilation
(air exchange) settings for containers |
5 m3/hr |
| Storage life | 2 months |
| Climateric/non-climacteric | Non climacteric |
| Ethylene production | Very low |
| Ethylene sensitivity | There are no reports of sensitivity to ethylene |
| Modified/controlled atmosphere | - |
| Potential benefits | - |
| Availability | On demand |
Harvesting and handling
Coconuts are the stone fruits of the coconut palm which flourish best in tropical coastal regions (salt spray). The native habitat of the coconut palm is not known with certainty because coconuts can float for considerable distances in seawater without losing their ability to germinate. As a result, coconuts palms are now to be found on tropical beaches worldwide.
50 - 120 fruit may be harvested from a single coconut palm. Each fruit weighs 1 - 2.5 kg.
A longitudinal section through a coconut reveals the following structure: the coconut is enclosed in a leathery, glossy outer skin (exocarp), which is of a yellow-green to yellow-brown colour and is watertight. Under the exocarp is a spongy, fibrous husk (coir) or mesocarp, which is 4 - 6 cm in thickness. This layer corresponds to the flesh (pulp) of other fruit. The fibrous husk is removed from the hard nut with a spike. The fibres are processed to produce carpeting, mats and the like. Removal of the coir reveals the familiar coconut. The outer layer of the coconut is a brown, very hard endocarp, approx. 0.5 cm thick, which is a rounded, triangular stone, the blunt end of which has three "eyes", i.e. germ pores set in pits.
Moving inwards, the following layer is the solid endosperm, an oily layer 1 - 2 cm in thickness which is protected by a brown seed coat and, once dried, yields copra. The seed coat contains antioxidants which protect the oil-rich seed from atmospheric oxygen so preventing it from becoming rancid (oxidative rancidity).
The kernel is hollow and 95% full of clear coconut milk (liquid endosperm).
Coconuts which are intended for transport have generally already had the outermost two layers removed.
Young coconuts are harvested 6 to 9 months after flowering, as the nut approaches full size and the skin is still green and the short stem on the top of the individual coconuts that originally held the male flowers (‘rat-tail’) becomes half green and brown. In immature nuts, the skin surface around the calyx (cap) on the top of coconuts is creamy-white or a whitish yellow. When the area surrounding the cap is green the coconut is regarded as mature and is 10 to 12 months old. At maturity the skin begins to change from green to yellow then brown and the ‘rat tail’ is entirely brown.
Coconuts which are 6 - 7 months in age contain the most milk. As ripening continues, the coconut milk solidifies to form white kernel or flesh (copra). Once all the milk has solidified, the flesh takes on a soapy flavour, becomes inedible and is worthless.
Maturity, size, freedom from blemishes, cracking, freedom from fibre of husked coconuts, and wet mouldy eyes are major quality characteristics.
Fresh coconuts are mainly eaten raw. Further coconut products: sterilized coconut milk for alcoholic drinks (e.g. pina colada), desiccated coconut, coconut fat, Coconut Oil, coconut fibres, copra.
In order to ensure safe transport, bags with de-husked coconuts must be stowed and secured in the means of transport in such a manner that they cannot slip or shift during transport. Attention must also be paid to stowage patterns which may be required as a result of special considerations, such as ventilation measures.
Coconuts are extremely sensitive to pressure, impact and jolting/vibration. Incorrect handling quickly results in smashed and burst fruit, which are worthless and also give rise to mould and rot on adjacent, unblemished nuts. There is also a risk that the nuts will burst under excessive stack pressure. Hooks must not be used.
Shipment / Storage
Cooling and storage of fresh Coconuts
Room-cooling is generally used for pre-cooling mature husked nuts. Forced-air and hydro-cooling are acceptable. A rapid temperature change of 8°C can cause cracking.
Mature coconuts with husk can be kept at ambient conditions for 3 to 5 months before the liquid endosperm has evaporated, the shell has cracked because of desiccation or sprouting has occurred.
Storage at 0°C to 1,5°C and 75% to 85% RH is possible for up to 2 months for mature, de-husked coconuts and 13°C to 16°C and 80% to 85% RH for 2 weeks or less. Low RH and high temperature should be avoided.
As ripening continues, the coconut milk solidifies in the fruit to form white kernel or flesh. Once all the milk has solidified, the flesh takes on a soapy flavour, becomes inedible and is worthless. As a result, coconuts have only a limited storage life (up to a maximum of 2 months).
Young coconuts are normally held at 3°C to 6°C with 90% to 95% RH, while wrapped, trimmed and shaped fruit can be held for 3 to 4 weeks. Shaped young coconuts treated with 0,5% to 1% sodium meta-bisulfite, can be held at ambient temperature for 2 days before browning occurs, while those treated with 2% sodium meta-bisulfite can be held at ambient temperature for 2 to 7 days. Young coconuts that have not been de-husked can be stored for a longer period than de-husked or trimmed/shaped young coconut. During storage, the taste of de-husked or trimmed/shaped coconuts sours earlier than of non-dehusked coconuts. The husk acts as insulator and may increase the storage-life of young coconuts.
Coconuts produce ripening gases (particularly CO2) as a result of the respiration processes which continue postharvest. Hence, some fresh air ventilation is required.
When stored at 0°C, immature nuts have green skins that turn brown after 7 days; few other changes occur in other quality characteristics at this temperature.
Controlled atmosphere considerations
No data are available on CA storage. Mature de-husked coconuts are waxed or film-wrapped to reduce water loss. Immature husked nuts can also be film-wrapped or waxed, however the outside colour changes rapidly from white to brown unless dipped into sodium bisulfite.
Desiccated Coconuts
This is the kernel of the coconut dried and prepared. Can be shipped in 5-ply kraft paper bags with a polythene liner. Prone to infestation by weevils. Weevils are not inherent in the commodity but penetrate from outside. Infestation may be due to the copra beetle and the sawtooth corn beetle which will attack the coconut if it is in proximity to infested commodities. Infested coconut can usually be screened and fumigated. In order to avoid contamination at source there must be strict cleanliness and prompt closure and sealing of bags after filling. After packing the coconut should be kept clear of any commodity liable to be infested.
If wet damaged in transit, coconut will develop mould and become rancid. Coconut is liable to become yellow and rancid with age, but only after several years.
For coconut 'cracking' see: http://pdf.usaid.gov/pdf_docs/pnacy843.pdf