Areca Nut Curing

Areca nut (Areca catechu) is popularly known in India as Supari and Shrivardhani. In Meghalaya it is named as Kwai. It thrives in the area owing to heavy rainfall and good drainage. The areca nut is a shade loving plant. The climatic conditions of Meghalaya suit the trees due to the high rainfall (3000 mm). Steep slopes allow continual drainage and clouds provide enough shade for the luxuriant growth of the plant. There is around 6200 hectare area under nut cultivation, which yield around 4200 to 5900 tonnes of the produce every year in the state. Areca nut is considered to be a native of Malaya. This is extensively grown in North Eastern part as well as peninsular Indian region. The palm is tall and slender with a smooth whitish stem reaching a height of 12 to 18m. The stem surmounted by a crown of pinnate leaves. 1-2 m long among which the pinnate is confluent. The fruit is ovoid which is approximately 2.25 cm across and 3.79-6.00 cm long. The fully ripe fruits look bright orange. The pericarp (60%) is hard and fibrous and the kernel (seed 40%) is called areca nut. The nut is about 2.25-3.25 cm in diameter, 2.00-3.00 cm long, varying in shape from conical to spherical and brown in colour with the white tints.

Method of Consumption and Curing in NE Region

The fruit (nut) is consumed in different manners. The crudest way is to get the ripe fresh fruit, shell it with a knife and then cut it into four pieces. One such piece is consumed (chewed) with lime and betel leaf. Ripe fruits are generally harvested for a large scale sale. The nut is also consumed after curing in water. The fresh fruits with husk (little less ripe) are cured in flowing water for some period. The process helps in loosening the husk. This way husk can come out from the nut by hand. About 22% of husk still remains over which is removed with the help of knife. The nut is consumed along with lime and betel leaf and relished by the local khasis. The curing is mainly for taste, improvement in colour and easy removal of husk. These practices are common in Meghalaya.

Assam and Tripura also grow areca nut extensively. In Tripura state the dry nut is consumed in small pieces with betel leaf and lime. No special type of curing is practiced in the state. Nuts are cured in Upper Assam by keeping the fruits in the pits. A circular pit is dug in the open area around the houses. The size of the pits varies from 2 to 3 m in diameter and 3 to 4 m in depth as required. The pit is plastered with leaves and cowdung at the bottom and inside on the wall. The freshly harvested fruits are charged normally in April and early May for curing. The upper half-meter layer is again filled with leaves, cowdung up to the ground level. Then the pits are opened in December to January for sale and consumption of the cured produce. Another popular method of processing of nuts in Assam consists of boiling of the immature fruit for about 2 hours after the removal of husk and drying in the sun. The produce is known as Chikani. Such fruits are relished by local Assamese people. The modern methods of nut- producing consists of reducing the nut into slices, wafers or grits, followed by drying, flavouring, scenting, colouring and softening. Such processed nut is chewed with betel leaf and eaten sometimes directly.

The water used to be changed every week. Now the areca nuts are cured collectively as a community project in the Ri-War area of Meghalaya (near Cherrapunjee). A typical curing of Areca nut (figure above) consists of the following components;

1. Curing pond: A pond for the curing of Areca nut is constructed of stones and masonry. It is normally in the size of 15m length, 10m width and 2.5m depth. Such a pond can take 150 baskets of nuts. The size and shape of a pond may vary as per requirement and the land scape of the area; however the depth remains the same.

2. Water flowing Channel: The perennial stream is the main requisite for the location of a pond. In the typical arrangement, water flow is diverted from the upstream of the nearby pond at one end and outlet is kept diagonally opposite of the inlet. The water level maintained 2.35 m from the bottom with the continuous flow.

3. Holding basket: The holding baskets are locally (Nongpriang village) prepared of bamboo by matting of the size of 1m diameter a top and 2.65 m height with the square bottom of 0.65m. The matting is done with 1 cm bamboo strips by keeping the 3 cm perforation. Each basket has a capacity to hold 1200 kg of areca nut which is equivalent to 12 gunny bags of areca nut.

4. Raising basket: A small bamboo basket is used for raising the cured fruit from the pond. This basket is matted in the size of 36 cm diameter a top, 30 cm high with the square base of 16 cm.

The Method

The pond is at first fragmented into the square of 90 cm x 90 cm each at the top with frames made of the strong bamboo. Thus the holding baskets of 1 m diameter when inserted into these squares could be reduced to that size. The bamboo frames hold the individual baskets and keep them vertical. These baskets are filled with the freshly harvested areca nut. Fruits normally float on the water. The baskets are therefore covered with jute clothes and stone weights are kept over them in order to ensure the proper curing. Once the areca nuts are charged into the holding baskets, then they are not disturbed till the curing is completed. No special care is required except the maintenance of the water level of the pond and water flow. The minimum water flow is assured (361it/min) to prevent the fruits from being spoiled. Excess water flow is considered good for keeping the fruit fresh.

The criteria for adequate curing are: (i) Yellow colour turns prominently bright yellow and (ii) the husk gets freed from kernels. The normal curing time is around 4 to 5 months. The fruits are then taken out from the pond. The fruits are sometimes cured for one and half months and disposed as and when demand for them arises. Once the fruits are raised from one holding basket then that basket should be completely raised out otherwise the rest of the fruits will be spoiled. The loss in curing is generally 15-30% of the total weight. The loss can be minimized by keeping the same lot in one basket. The units of fresh fruits and nuts in one kg amount to 42 and 75 in number respectively. The dry nuts in one kg however amount to 135 in number. Curing improves colour, taste and freshness of the nut. Cured kernels are less astringent and are better to chew and taste.

Economics

These ponds are constructed by local masons. The cost of the construction of the pond approximates Rs. 20,000/- not including the channel-outlet for water. The owner charges Rs. 50/- per basket (1200 kg) from the growers. Thus one pond owner earns minimum Rs. 7,000/- per 150 baskets capacity pond for one curing. Such curing is done twice a year, and thus utilizing its full capacity.

Preservation of Fruits

Fully ripe arecanuts after preserving are used throughout the year. These are quite very popular in Kerala and Assam. In Assam, fresh fruits are preserved in thick layers of mud. This product is known as Bura Tamul. In Kerala, fresh fruits are stored by steeping in water, resulting in discolouration of outer husk and foul smell due to bacterial attack but the inner core is well preserved. This product is known as Neettadakka. Use of a solution containing sodium benzoate (0.1 %) and potassium metabisulphate (0.2%) acidified to a pH of 3.5-4.0 with hydrochloric acid for steeping ripe nuts after initial heat blanching is suggested to eliminate the foul smell and improve the quality of nuts.

Dried ripe nuts: The most popular trade form of arecanut is dried whole nut known as Chali or Kottapak.  Ripe nuts are dried in the sun for 35-40 days, dehusked and marketed as whole nuts. The optimum moisture content is around 12%. Inadequate drying results in fungal infection and in a poor quality product. Depending on size, different grades of decrease order are Moti, Srivardhan, Jamnagar and Jini. The main producing states of Chali are Kerala, Karnataka, Assam and Maharashtra. To facilitate drying and dehusking, the fruits are cut longitudinally into 2 halves and sun-dried for 10 days. The kernels are scooped out and given a final drying. This product, known as Pareha, is popular in Kerala and Karnataka. Mechanical driers are also used to make Chali. Drying takes 60-70 hours over a period of 7-8 days at 45° - 75°C. The dehusking can be done using a manually-operated arecanut dehusker developed by CPCRI, Kasaragod. About 40 kg chali can be made within a period of 8 hours.

Kalipak:  It is another important processed product of arecanut. Kerala and Karnataka are main producers of Kalipak. Tender nuts of 6-7 months are dehusked, cut into pieces, boiled with water or a diluted extract from previous boiling, coated with kali and dried. Kali coating can be repeated 3-4 times to get a glossy appearance. Kali is the concentrated extract obtained after 3-4 batches of boiling. The kalipak is known by different names depending on number, shape and size of the cuts. Api or unde (without any cuts), batlu (transverse cut into halves), choor (several longitudinal cuts), podi (both longitudinal and transverse cuts) and erazel (transverse thin slices). Iylon is another variety made from green nuts which are cut transversely into 5-6 discs and without kali coating. During preparation of kalipak, the tannin content is reduced substantially. A well-dried product with a dark brown colour, glossy appearance, crisp chewing feel, well-toned astringency and absence of over-mature nuts are rated superior.

Scented supari: It is made both from chali and kalipak. Chali supari is more popular. The dried nuts are broken into bits, blended with spices and flavour mixture and packed in butter paper. Instead of raw spices, essential oils are used for easy blending, with coconut gratings to avoid microbial growth. Saccharin is occasionally used for sweetening. Rose essence and menthol are commonly used for flavouring.

Uses of Arecanut Constituents and Byproducts

• Tannins: Polyphenols or tannins from the major constituent of the nut. Tender nut contains tannins 30-37 %, while ripe nuts have only 16-22 %. The areca tannins obtained as byproduct from tender nut processing can be utilized for drying clothes, leather, rope, for making black writing ink along with ferrous sulphate, as an adhesive in plywood manufacture and even as food colour.

• Fat: The nuts contain 8-12 % fat, which is extractable with organic solvents like hexane or chloroform. The fat is rich in myristic acid and can be a good source of myristic acid and its derivatives. Refining of fat with alkai makes it edible. It can be mixed with cocoa fat for confectionery products and as an extender to cocoa butter for various products. It can be a substitute for vanaspati in preparations of sweets and biscuits.

• Alkaloids: Arecanut has 1.5% of alkaloids such as arecoline, arecoline, arecaidine guvacine, idoguvacine and guvacolidine. Of them, arecoline alone accounts for 0.24 %. They possess anthelmintic property and are effective against tapeworms and rounworms. It is also used as a CNS depressant drug. It has got anti-bacterial property and inhibits the growth of Escherichia coli, Staphylococcus typhi and Staphylococcus aureus. The blood sugar lowering effect of arecoline is mentioned in Ayurveda.

• Areca husk: The husk of arecanut constitutes 60-80% of the total weight of fresh nut. Several processes have been developed for utilization of areca husk for making hard boards, plastic boards and brown wrapping paper. The husk fibre extracted by soaking in water for 3 weeks and beating with a mallet can be used for thick boards, fluffy cushions and non-woven fabrics. It can be a good source of furfural and xylose for industrial applications.

• Areca stem and leaf sheath: Arecanut stem is a useful building material. Its timber can be used for making a variety of elegant utility articles like rulers, shelves and waste-paper baskets, due to its hardness. Hollow stem can be used as drainage and irrigation pipes. A process has been developed at CPCRI, Kasaragod, for making plyboards from leaf sheath for tea chest, sint case and file board manufacture. The CFTRI, Mysore, has developed a machine for making cups and throw-away plates which can substitute the paper plates.