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Agriculture > Plantation Crops > Cashew (Anacardium occidentale)

Harvesting & Storage

Harvesting

Economic bearing in cashew commences after 3rd year of planting. After producing clusters of flowers, cashews produce the edible apple, and also a nut encased in a heavy shell, which is the true cashew fruit. The cashew tree flowers for two or three months and fruit matures about two months after the bloom. The cashew nut forms first at the end of the stem. Subsequently, the stem swells to form the "apple" with the nut attached externally.The cashew nut is 2.5-4.0 cm (1.0-1.5 inches) long and kidney shaped. Its shell is about 5 mm thick, with a soft leathery outer skin and a thin hard inner skin.

The harvesting and processing of cashew is very labour intensive. When fully ripe, it falls to the ground. Harvesting generally involves collecting the nuts once they have dropped to the ground after maturing. Workers scour the area and detach the nut from the fruit. For the nuts to be easily traced, the surface under the tree has to be free from weeds. In some places, the whole area under the tree is swept free of dry leaves. The nuts are generally collected in baskets or sacks. Cashew fruit are generally left to fall to the ground before being collected, as this is an indication that the kernel is mature. If fruit are picked from the trees, the cashew apple will be ripe, but the kernel will still be immature.

The quantity of nuts, which can be harvested, depends upon the yield of the trees. The yield starting from 1 kg in 3rd- 4th year, goes on increasing as the canopy develops and one can expect more that 10 kgs. of nuts in 8 to 10 years old plant depending on management. Where many nuts fall together, much less time is required for walking in search of them. On average, each individual can harvest a maximum of 50 kg per day. A very limited number of nuts fall at the beginning of the production season. A peak in the number of nuts falling is gradually attained and production slowly declines.

In very dry climates where the topsoil remains dry overnight, nuts can be left under the trees for several weeks without their quality being affected. However, where humidity of the air or soil causes moisture and dew formation, the nuts should be reaped at least twice a week. This is not very economical, unless it is carried out on smallholdings with relatively high labour intensity, as there will not be adequate numbers of nuts to harvest sufficient quantities to achieve collection levels of 50 kg per day (Ohler, 1979).

Apples to be used for processing into products such as jam or juices, should be picked from the tree before they fall naturally. On falling to the ground, apples may become damaged. Once damaged, the apples may ferment and deteriorate quite rapidly. The riper the apple, the sweeter the taste. It is therefore recommended that the apple is picked as it is about to fall. At this stage the nut is fully-grown and is ripe and ready for harvest.

Apples which are not within reach of the picker’s hands can be harvested using a small basket or sack attached to a ring at the end of a long stick. Fully ripe apples will drop into the sack when the tree is shaken. Apples that have not matured completely, should be cut off with a small knife attached to the stick. The nuts must remain attached to the apple, since some juice may be lost on their removal.

The cashew apple will only keep for 24 hours after it has been picked. Transporting large quantities of apples is difficult for this reason . When stacked in layers, apples may burst and lose their juice because of the weight on top of them.

Storage

Technical requirements for storage are dependent on weather conditions. As cashew nuts are usually produced in climates with a long dry season, simple buildings with concrete floors and walls, and roofs of corrugated metal, should provide adequate storage.

Certain prerequisites must be satisfied to ensure safe storage:

  1. a waterproof, dry floor;

  2. a firm and secure roof;

  3. openings in the wall must be protected in order to prevent water from entering the room;

  4. headroom must be adequate, so as to allow the bags in a stack to be moved around if large quantities are to be stored;

  5. the store should be easily inspected: there must be sufficient clearance between the wall and the bags, so as to allow individuals to walk around and check the condition of the stack;

  6. the stack must be placed on a raised wooden platform, in order to prevent moisture from being drawn from the floor to the nuts

Infestation of harvested nuts

Raw cashew nuts, stored in sacks, sometimes in the open awaiting shipment, and frequently without protection from rain, are subject to infestation through the stem-end, and this may go under detected until damage has progressed to the point of heavy loss. Infestation also occurs in the shelled kernels at various stages of handling.

Post-harvest handling

The nut is encased in a rock hard shell that is virtually impossible to penetrate after harvest. In order to extract the nut, the whole shell is soaked in water, softened by steaming, and carefully air-dried to the final moisture content (9 percent). Each nut is hand massaged and cracked via a manual process that entails putting the nut against one sharp blade and bringing another blade, which is on a foot powered lever, through the outer shell. The blade on the foot lever is raised by an enthusiastic stomp allowing the outer shell to separate from the nut. The nut inside is carefully picked out of the outer shell using a nut pick.

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