Eugenia caryophylla: Clove plant Morphology, Cultivation practices, Processing and Economic importance

Economic Botany-Morphology, Cultivation and uses of Clove plant

Clove

Botanical Name: Eugenia caryophylla              Family: Myratacae            Common Name: Laung

Morphology

 It is a small evergreen tree belongs to family Myratacae. It grows up to 20m height but when cultivated it reaches up to 10m.

·       The stem form conical crown when young and become pyramidal or cylindrical when mature.  It is erect and has grey bark.

·         Leaves are simple, arranged oppositely. They have a leathery and shiny texture on the upper (adaxial) surface, and are aromatic when crushed. New leaves are bright pink in colour and turn light green and glossy. Each leaf is around 10cm long and 5cm wide, elliptic or oblong, very narrowly attenuated at the base, and point upwards.

·       The clove tree is composed of leaves and buds (the commercial part of the tree) and the flowering bud production begins four years after plantation.

·       The flowers can appear seperate or in an infloroscence that starts from leaf axils. Flowers are arranged in form of terminal clusters. Unopened flower buds are green first, then slowly change to pink or red or crimson, then finally bright red when in full bloom.

·       Each flower bud consists of a peduncle (Hypnthium), four distinct triangular calyx lobes, four crimson unopened petals surrounding numerous stamens and a central columnar style. The hypanthium represents the enlargement of the receptacle. The bicarpellary inferior ovary is enclosed by a more or less fleshy receptacle. The hypanthium is a small angular peduncle, flattened at the base. It has numerous oil glands that impart a characteristic aromatic odour.

·       The leaves, unripe fruit and broken clove including the stalk are all aromatic and yield essential oil to pink or red or crimson, then finally bright red when in full bloom.

·       The tree becomes fully mature in 20 years and can bear fruit for more than 80 years. The flower buds gradually develop in colour and are ready for collecting when they turn bright red. Cloves are handpicked before the flower opens. Harvested cloves are 0.5-0.75 inches long and consist of stems with four unopened petals which form a small ball in the center.

·       The fruit is Berry and in many cases it is edible.

Cultivation: Eugenia caryophylla is a small symmetrical evergreen tree. Crimson red flowers are produced in clusters often in wild growing plants, but under cultivation the trees are not allowed to bloom. The flower buds are Hand picked when they are dull red and then sun dried on a mat or in a kiln. Good quality cloves are bold, plump, rough but not wrinkled. The clove tree thrives best in deep volcanic, loamy soil, and requires a warm humid climate. Clove is propagated by seeds, which are usually planted in nurseries and then transplanted into the field.

Processing of Clove:-

Harvesting: Time for harvesting is when the clove tree is of 6-8 years old. The timing of harvest of the clove buds is critical. The buds should be harvested before the purple or crimson flowers start to develop. Clusters of flower buds are hand-picked from the branches. It is important that the branches are not removed or damaged as this will reduce the yield of future crops. The correct time of harvest is when the outer green leaves (the calyx) of the flower bud change from olive green to yellow pink and before the petals fall to expose the stamens.

Drying: The drying process takes about four to five days. The final moisture content of the dried cloves should be 8-10%. The clove buds will first be cleaned and washed manually and then sun dried. Solar drying is the cheapest and popular mode of drying agricultural products. The dry clove bud enters to the milling unit in which milling and pulverization operations are carried out.

Winnowing & Grinding:  Winnowing is done to remove dust and other foreign matter. Small cleaning machines are available that use a blower to remove the dirt and dust. Other than that traditional processes like using basket for removing dust can also be considered for small scales. Grinding can be a method of adding value to a product. However, it is not advisable to grind spices. After grinding, spices are more vulnerable to spoilage. The flavour and aroma compounds are not stable and will quickly disappear from ground products.

Packaging: Cloves can be packaged in polythene bags of various sizes according to the market demand. The bags should be sealed to prevent moisture entering. Sealing machines can be used to seal the bags. Attractive labels should be applied to the products. The label needs to contain all relevant product and legal information

Storage: Dried cloves must be stored away from direct sunlight and must be stored in moisture-proof packaging materials. Also ensure that the cloves are fully dried before storage. Moisture will cause the cloves to rot and starts fermentation. The stored cloves should be inspected regularly for signs of spoilage or moisture. If they have absorbed moisture, they should be re-dried.

Phytochemicals                                                                           

The compound eugenol is responsible for most of the characteristic aroma of cloves. Eugenol comprises 72–90% of the essential oil extracted from cloves, and is the compound most responsible for clove aroma.