The harvesting and processing of cashew is very labour intensive. Goa, practices a unique harvesting system. In other parts of India, fruits are picked from the trees. This is because the fruit is thrown away as they do not have any use for it. If done so, the cashew apple will be ripe, but the kernel will still be immature.
In Goa however a “Feni” a local variety of liquor is extracted from the cashew apple and generates additional revenue for the farmers. Hence, the fruit is as important as the nut and picked only when it is fully ripe. When fully ripe, the cashew apple falls to the ground. This is an indication that the kernel is mature. At this stage the nut is fully-grown for about two weeks and is ripe and ready for harvest. The riper the apple, the sweeter the taste.
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. The nuts are generally collected in baskets or sacks. Although activities are labour intensive and time consuming, they are not heavy and women and children can help.
Cashew nuts are dried in the sun to reduce the moisture content of the nut and to mature the seed in the infra-red and ultra-violet rays of the sun.
Cashew nuts should keep for 12 months or more. Moisture content may cause deterioration of the kernel due to mould or bacterial attack, or enzyme action. The nuts are hence dried after harvesting to preserve their quality.
Sun drying of cashew nuts are done on specially prepared drying floors, The drying areas are smooth and slightly sloping, so as to allow rainwater to run off. The nuts sare constantly raked in order to ensure that they all receive the same benefit of the sun’s rays and therefore they are dried evenly.
The nuts must be prepared for the removal of shells. The nuts are roasted in a steam boiler in order to avoid scorching during the roasting operation. The application of heat to the nut releases the CNSL and makes the shell brittle, thus facilitating extraction of the kernel when breaking the shell open.
The objective of shelling is to produce clean, whole kernels, which are free of cracks. Shelling has always been manually performed in India. Other countries have difficulty in competing with the great skill of Indian workers. India has therefore enjoyed a virtual monopoly of cashew processing for a long time
Shelling is 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 nutpick. After shelling, shell pieces and kernels are separated, and the unshelled nuts are returned to the shelling operation.
The shelled kernel is covered with the testa, the removal of which is facilitated by drying the shelled kernel, to produce the blanched kernel. Drying causes shrinkage of the kernel, thereby allowing the testa to be easily removed either mechanically, or by hand with a knife. Drying also protects the kernel from pest and fungal attack at this vulnerable stage.
Drying usually takes six – eight hours, at a temperature of around 70°C- 75.C. A uniform temperature throughout the drier is essential to avoid under-drying or scorching. A Tray dryer is used, for drying cashew kernels. The dryer contains a series of mesh-bottom trays that are slotted into the drying cabinet. The trays are of a size that can be lifted when full. Hot air circulates over the trays and is exhausted through the chimney. Cashew oil cakes are burned to provide the heat source.
At this stage, the testa is loosely attached to the kernel, although a few kernels may have already lost the testa during prior operations. Those parts still attached to the kernel, can be removed by scraping of the testa with a blunt knife, which is the most effective way of removing it. It is essential that the testa is removed with minimum pieces. It is also essential that the entire testa is removed. The testa is gently scrapped with a blunt knife and removed.
At the end of the day, the removed testa is winnowed and all cashew pieces removed. The dust and very fine pieces that cannot be peeled, together with the diseased pieces, are classified as refuse. The browns kernels, which are not been separated out during the shelling operation, are removed and discarded.
Strict cleanliness in the peeling operation is observed in the peeling room and its facilities, by all personnel. All workers follow basic codes of hygiene.
The peeled kernels are vulnerable to insect infestation and mould growth. They are also prone to rodent attack and are stored in rodent-proof containers or rooms.
In order to safeguard and guarantee quality, producers and exporters have introduced quality standards which must be met by cashew exporters.
Cashew kernels are selected on the basis of the number per unit weight, in accordance with the weight of the kernels. They are also classified either as wholes, chips, splits, butts or baby bits, in accordance with the integrity of the kernel. White or ivory kernels are preferred over brown ones. There is a maximum permitted moisture level (both for raw cashews and cashew kernels) and the product must be free from insects, mould, rancidity and extraneous materials.
The highest price is paid for better quality kernels of the W180 and W210 grades which are the largest and heaviest grades.
The grading operation is important since it is the last opportunity for quality control of the kernels. After the kernels are extracted from the shells, dried and peeled, they are graded for export according to size and condition. The grading system is known as the American Standard, which is also incorporated in the Indian Government export criteria. Kernels are categorized on the basis of colour and condition. Peeled cashew nuts can be classified into between 11 and 24 grades. These are roughly divided into three groups: white whole, white pieces and scorched grades. The three groups are further broken down as follows:
W180 (super Large): Between 120 and 180 kernels per lb (266-395 per kg)
W210 (large): Between 200 and 210 kernels per lb (395-465 per kg)
W240: Between 230 and 240 kernels per lb (485-530 per kg)
W280: Between 270 and 280 kernels per lb (575-620 per kg)
W320: Between 300 and 320 kernels per lb (660-706 per kg)
W450: Between 400 and 450 kernels per lb (880-990 per kg)
Butts: A kernel broken cleanly across the section of the nut.
Splits: A kernel which has broken down the natural line of cleavage to forma cotyledon.
Pieces: A kernel which has broken across the section but does not qualify for a butt and is above a specific size.
Small pieces: As above but smaller.
Baby bits: Very small pieces of kernel which are white in colour.
Wholes: Whole kernels that have been slightly scorched during the process but are otherwise sound. These are not graded according to size.
Butts: Butts that have been scorched.
Splits: Splits that have been scorched.
Pieces: As for pieces, but which have been scorched during processing and contain all but the very small pieces.
Throughout the grading of white whole kernels, the weight must be constantly checked. This is done with the use of a small counter scale with 250g (½lb) of graded kernels accurately weighed out and counted. From this, the count per kg (or per pound) can be calculated.
Quality has emerged, ahead of price, as the most vital criterion for any item if it is seeking entry into the global market. Quality aspects include safety, reliability, durability and acceptability of the product to the consumer. Small-scale processors have to match the standards set by importers, consumers and standards agencies. Quality assurance procedures are an essential element of any processing operation to ensure product consistency between different batches.
The normal packaging used for the export of kernels is air-tight cans or flexi packs of 25lbs (11.34 kg) weight capacity. The packaging material needs to be impermeable, since cashew kernels are subject to rancidity and go stale very quickly. Cashews are packed in cans made out of food grade electrolytic tin plates or flexi packs
After filling and weighing, all the air from the tins are removed by creating a vacuum in each and subsequently substituting it with carbon dioxide (CO2). The advantages of packing cashew kernels in carbon dioxide are two-fold. Firstly, carbon dioxide will not support life so any infestation that may have been present is therefore arrested. The kernels are therefore tightly sealed, thus preventing movement and breakage during transport.
Cashew kernels are offered to US and EU in food grade flexi packs wherein the kernels are packed under vacuum with CO2 and N2 in the ration of 60:40. This is the most accepted packing of cashew kernels, as the buyers don’t have to bother much to dispose off the cans after taking out the kernels.