Elettaria cardamomum (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

1, habit fruiting clump; 2, leaf; 3, part of inflorescence; 4, flower; 5, fruits; 6, seed with aril

Elettaria cardamomum (L.) Maton

Protologue: Trans. Linn. Soc. London 10: 254, t. 5 (1811).

Family: Zingiberaceae

Chromosome number: 2n = 48, 50, 52

Synonyms

• Amomum cardamomum L. (1753),
• A. repens Sonnerat (1782),
• Alpinia cardamomum (L.) Roxb. (1819).

Vernacular names

• Cardamom, true cardamom, small cardamom (En)
• Cardamome (Fr)
• Indonesia: kapulaga sabrang (general), kapol (Sundanese), kapolaga (Sundanese)
• Malaysia: biah pelaga
• Burma (Myanmar): bala, pala, panlat
• Cambodia: krako sbat
• Laos: hma:k hnè:ngx
• Thailand: krawan-thet (central)
• Vietnam= trúc sa, bạch dậu khấu

Origin and geographic distribution

E. cardamomum occurs wild in gaps in the evergreen montane monsoon forests of the western Ghats in southern India and the western highlands in Sri Lanka. It is possibly also truly wild in Burma (Myanmar), Indo-China and Malesia, and has been introduced into other parts of the tropics. Introduction into Guatemala in the 1920s was particularly successful and a sizable production and export developed.

Uses

Cardamom is the dried fruit of E. cardamomum. The major use of cardamom is for domestic culinary purposes. The spice is used in the form of the whole fruit, the decorticated seeds, or the ground seeds. In Asia, cardamom plays an important role in a variety of spiced rice, vegetable and meat dishes. It is used to flavour coffee and tea and is an important ingredient of curries. In the food and beverage industry it is used for flavouring confectionery, a range of baked goods, prepared savoury dishes, and a range of beverages. Locally it is a masticatory often included in the betel quid, and industrially it is used to a small extent in flavouring tobacco.

Cardamom is included in several pharmacopoeias. It is considered tonic to the heart, stomachic, laxative, diuretic, and carminative. It lessens inflammation, headache, earache, toothache, and alleviates disorders of the liver, chest and throat. Cardamom is commonly given in instances of snake bite and scorpion sting, but it is not an antidote.

Cardamom essential oil is produced in small quantities in some western spice-importing countries and also in India, Guatemala and Sri Lanka. It is mainly used in the flavouring of processed foods, but also in certain beverages such as cordials, bitters and liqueurs and occasionally in perfumery. In the United States cardamom oil is "generally recognized as safe” (GRAS 2240/2241). The maximum permitted level in food products is about 0.01%.

Cardamom oleoresin, which is also produced in some western spice-importing countries and in India, has similar applications to the essential oil but is used less extensively. Both the oil and oleoresin tend to develop off-flavours when exposed to the air for prolonged periods, so their use is generally confined to meat products with a short shelf-life, such as sausages.

Production and international trade

True cardamom is one of the highest-priced spices on the market. It is traded internationally predominantly in the form of whole fruits, to a much lesser extent as decorticated seeds. The major suppliers are Guatemala, India, Sri Lanka and Tanzania, with Papua New Guinea being a relatively new player on the world market. Average annual production in the 1990s was 10 000 t, with Guatemala providing 5000 t, India 4000 t, and the rest of the world 1000 t. The cultivated area in the 1970s was about 90 000 ha in India. The major consumers are the Arab countries in the Middle East (flavouring of coffee and tea) and the Scandinavian countries (flavouring of baked goods and pastries).

Properties

The dried fruit of cardamom contains an essential oil, fixed (fatty) oil, pigments, protein, cellulose, pentosans, sugars, starch, silica, calcium oxalate and minerals. The approximate composition of dried fruits per 100 g is water 20 g, protein 10 g, fat 2 g, carbohydrates 42 g, fibre 20 g, ash 6 g. The major constituent of the seeds is starch (up to 50%) while in the capsule (husk) it is crude fibre (up to 31%). Whole cardamom fruits usually have an essential-oil content of 3.5-7%. The essential oil is located predominantly in the seeds which comprise 59-79% of the whole dried fruit weight. The seeds of freshly harvested cardamom may contain as much as 11% essential oil, but the husk rarely contains more than 1%. Cardamom oil is best obtained by steam distillation of freshly decorticated seed. It is a colourless or pale yellow oil which darkens on exposure to light. The essential oil comprises mainly 1,8-cineole (20-60%) and α-terpinyl acetate (20-53%) together with smaller amounts of other oxygenated monoterpenes, monoterpene hydrocarbons and sesquiterpenes. This oil gives cardamom the pleasant aroma and the characteristic warm, slightly pungent taste. A monograph on the physiological properties of cardamom oil has been published by the Research Institute for Fragrance Materials (RIFM).

The fatty oil content of the fruit has been reported to range from 1-10%; the oil is predominantly located in the seed. Ten fatty acids have been identified, with the major constituents being palmitic (28-38%), oleic (43-44%) and linoleic acid (2-16%). The relative abundance of the fatty acids apparently differs according to the cultivar grown, because high stearic acid contents (18-38%) have also been reported.

The 1000-seed weight is about 20-25 g.

Composition

Cardamom oil (from India) (Source: Gopalakrishnan, 1994)

• 38.8% 1,8-cineole
• 24.6% α-terpinyl acetate
• 6.2% β-pinene
• 5.7% linalool
• 4.2% sabinene
• 4.0% limonene
• 3.4% α-terpineol
• 2.3% α-pinene
• 2.0% terpinen-4-ol
• 1.0% linalyl acetate
• 0.8% geranyl acetate
• 0.2% geraniol
• trace nerolidol (unknown isomer)
• 93.2% total

Cardamom oil (from India) (Source: Variyar & Bandyopadhyay, 1995)

• 49.0% α-terpinyl acetate
• 24.7% 1,8-cineole
• 5.8% linalool
• 4.6% linalyl acetate
• 2.7% α-terpineol
• 2.5% geraniol
• 1.9% terpinen-4-ol
• 1.4% sabinene
• 1.2% myrcene
• 1.2% nerolidol (unknown isomer)
• 0.9% limonene
• 0.9% nerol
• 0.4% β-caryophyllene
• 0.4% α-pinene
• 97.6% total

Adulterations and substitutes

The cardamom substitutes ("false" cardamoms) that sometimes appear in trade and may be confused with true cardamom are derived mainly from species of Amomum and Aframomum K. Schumann. The most important one in Indonesia is round cardamom (Amomum compactum Soland. ex Maton). Other species labelled and used as "false” cardamoms in South-East Asia (see Chapter on "Minor spices” and "Spice plants with other primary use”) include Amomum acre Valeton, A. krervanh Pierre ex Gagnepain, A. ochreum Ridley, A. testaceum Ridley, A. uliginosum J.G. König ex Retz., A. xanthioides Wallich ex Baker and A. xanthophlebium Baker. The "false” cardamoms found outside South-East Asia include Amomum aromaticum Roxb. and A. subulatum Roxb. (Eastern Himalayas), Alpinia globosa Horan. (Indo-China and China), Aframomum corrorima (Braun) Jansen (Ethiopia), A. daniellii K. Schumann (Cameroon) and A. melegueta (Roscoe) K. Schumann (West Africa).

Cardamom oil is sometimes adulterated with 1,8-cineole and α-terpinyl acetate from cheaper sources.

Description

• Robust perennial herb, up to 5 m tall, growing in a thick clump, with branched rhizomes from which arise 10-20 erect leafy shoots (composed of the leaf sheaths) and numerous decumbent flowering shoots.
• Leaves distichous; petiole (free part) up to 2.5 cm long, sheathing at base and together with other sheaths forming the pseudostem; ligule entire, up to 1 cm long; blade lanceolate, 25-100 cm × 5-15 cm, apex acuminate, dark green and glabrous above, light green and glabrous or pubescent beneath.
• Inflorescence a prostrate (seldom erect) panicle, up to 1.2 m long, arising from the rhizome at the base of a leafy shoot; bracts alternate, lanceolate, up to 3 cm × 1 cm, each with an axillary, usually 2-3-flowered cincinnus; bracteole tubular, up to 2.5 cm long.
• Flowers bisexual, zygomorphic, about 4 cm long; calyx tubular, up to 2 cm long, with 2-3 teeth, green; corolla tubular, 3-lobed, tube as long as the calyx, lobes 1-1.5 cm long, pale green; labellum obovate, 1.5-2 cm long, up to 1 cm wide, obscurely 3-lobed, white but streaked with violet; lateral staminodes inconspicuous, subulate; anther sessile, thecas about 1 cm long, parallel, connective prolonged into a short crest; pistil with 2-3 mm long ovary, style slightly longer than anther, stigma capitate, small.
• Fruit a globose or subcylindrical trilocular capsule, 1-2(- 5) cm long, pale green to yellow, drying brown.
• Seeds 15-20 per fruit, angled, about 3 mm long, rugose, dark brown, aromatic, with thin mucilaginous aril.

Growth and development

Cardamom seeds germinate 5-7 weeks after sowing but germination is irregular and may continue even up to one year. Cardamom comes into bearing about 3 years after field planting, which may be 4-5 years after sowing. The economic life is 10-15 years. Flowers are self-sterile, therefore it is necessary to plant a mixture of clones. Pollination is by bees and ants. Flowering may occur throughout the year. The flowers open from the base of the panicle upwards over a long period, sometimes even more than one year. Flower buds require about 30 days from initiation to full bloom. Anthesis takes place predominantly during the early hours of the day. Pollen is shed mainly between 6 and 8 a.m., whereas the stigma is most receptive between 8 and 10 a.m. on the day the flower opens. Capsule development takes a further 110 days. After the panicles have flowered, fruited and died, the vegetative shoots bearing them also die off.

Other botanical information

Elettaria Maton is a small genus with 3-4 species in East and South-East Asia. The botanical identity of E. cardamomum is no longer contentious; what is problematic is the vernacular name "cardamom” for the spice which is often also used for many other taxa, particularly Amomum species (see adulterations and substitutes).

E. cardamomum is rather variable and 2 botanical varieties have been distinguished in the literature, one for the wild taxon and one for the cultivated forms:

• var. major Thwaites. This is the name given to the wild cardamoms that are particularly common in Sri Lanka and southern India. Plants are very robust (up to 5 m tall), inflorescences are erect, fruits elongate (up to 5 cm long) containing many large, but less aromatic seeds, which are also used like true cardamom.

• var. cardamomum (syn. var. minor Watt, var. minuscula Burkill). This is the botanical name for the cultivated cardamoms, which however, could better be classified and named as cultivar groups. Compared with the wild cardamoms, cultivated cardamoms are usually smaller plants (up to 3 m) with longer, prostrate inflorescences bearing more flowers producing smaller, subglobose fruits (1-2 cm diameter) with seeds that are more aromatic. The cultivated cardamoms can be grouped into many cultivar groups, the 2 most important ones being:

• • cv. group Malabar. Plants less than 3 m tall, leaves 30-45 cm long, panicles prostrate on ground 60-90 cm long, fruit small, globose, rounded or ovoid, lightly ribbed. Plants susceptible to katte virus.

• • cv. group Mysore. Plants resemble the wild cardamoms more; the fruits are fusiform, 3-angled, ribbed. They are more suited to higher elevations and show some resistance to katte virus.

Ecology

Evergreen montane forest land supplies the most favourable environment for cardamom, with soils varying from deep forest loam to white quartz gravel with only a shallow zone of humus accumulation. Cardamom is a plant of the early succession stage and appears in natural or man-made forest clearings but is not found in forests with an undisturbed canopy. On sloping land it may grow well in pockets of soil among boulders. In the main production areas in southern India and Sri Lanka, cardamom is grown at altitudes of 600-1500 m. A uniformly distributed rainfall of 2500-3800 mm per year is considered optimal. The tolerable range extends from 1500-5800 mm; months with less than 125 mm rainfall have to be regarded as drought months. Drought periods during the formation of the inflorescence or during flowering will preclude seed production and cannot be overcome by sufficient precipitation at a later stage. Successive droughts in two or more years endanger the plant as a whole. Optimum annual mean temperatures are considered to be around 22 °C. The diurnal temperature may vary between 10 °C and 35 °C. In the lowlands (annual mean temperatures > 24 °C) cardamom only propagates vegetatively; the plants do not grow where annual mean temperatures are < 17°C.

Cardamom does not tolerate prolonged exposure to direct sunlight; about 50% is thought to be optimal. Strong winds may topple cardamom plants as their root system is weak. Desiccation by dry winds is a serious threat, especially to young seedlings, but may also affect adult plants.

The crop does best in little-disturbed soils well supplied with organic matter and, since it does not tolerate waterlogging, with good drainage.

Propagation and planting

Cardamom is easily propagated vegetatively by division of rhizomes, but the transmission of mosaic virus is then a major problem. Several clones should be planted, to overcome self-incompatibility. The rhizomes of large clumps of growing plants are dug out and divided into small pieces, each with at least one old and one young shoot, which are planted in prepared holes. This method gives earlier yields than seedlings, but the supply of planting material is often limited.

For large-scale production it is common practice to sow selected seeds in specially prepared nursery beds. Cardamom seeds are best sown immediately after harvest because they remain viable for only 7-10 days. About 1 kg seed (50 000 seeds) will furnish enough plants for 1 ha in the field. The seedlings are transplanted to another nursery after 3-6 months when 15 cm tall, and are planted out in the field when 1-2 years old. The young plants are planted in pits, often 60 cm × 60 cm and 45 cm deep, which may be filled with surface soil, leaf mould, and, if possible, with some manure. Field spacing is 1.5-3 m × 1.5-3 m, leading to 1000-4000 clumps/ha. Shade is provided by planting cardamom either in montane forest after clearing the underbrush, or under planted shade trees. Cardamom is often intercropped in e.g. coffee, tea, areca nut or pepper.

Clonal propagation through tissue culture has been successful using rootstocks of seedlings raised in vitro. Differentiation of shoot buds, roots and leaves leading to the development of plantlets could be induced.

Husbandry

The young cardamom plants need careful attention in their first year. They need to be sprayed occasionally with Bordeaux mixture to prevent fungal attack and they must also be weeded regularly to keep down the regenerating undergrowth. After-care consists of occasional weeding, removal of old and dying stems, mulching, regulation of shade, manuring, and gap filling. Heavy applications of organic matter are recommended, supplemented by inorganic fertilizers (per ha 45-70 kg N, 35-45 kg P₂O₅, 45-100 kg K₂O).

Diseases and pests

The most important disease of cardamom in southern India is the mosaic virus known as katte or marble disease, transmitted by the banana aphid Pentalonia nigronervosa. Planting of diseased rhizomes is a serious source of infection. The only control measures appear to be the careful roguing of affected plants and the planting of non-affected seedlings. A nursery leaf rot, caused by Coniothyrium sp. or Phyllosticta sp., results in spotting and eventual rotting of the leaves in the nursery. The disease is worst in the wet season, but it may be controlled by timely application of Bordeaux mixture. Another disease is a rhizome or root rot causing a gradual decline in vigour of the plants. Rhizomes are often found to be rotten and covered with fungal mycelia of Cephalosporium sp., Pythium aphanidermatum and P. vexans. Affected plants may contain the rhizome borer Prodioctes haematicus. Control measures for the disease have not been properly investigated. Other diseases of minor economic importance include a leaf rust (Uredo elettariae) and a leaf-spot (Chlamydomyces palmarum).

Pests of cardamom include the thrips Taeniothrips cardamomi, affecting all cardamom growing districts in India. It lives in the leaf sheaths and the floral bracts. In extreme cases the flowers fail to set and this may cause a severe loss of crop. It may check fruit development and lead to malformations. The pest may be controlled by Gammexane dust containing the active principle BHC. The hairy caterpillar Eupterote mollifera (syn. E. canaraica) may appear in enormous swarms, attacking the leaves and defoliating entire clumps. It is a general forest pest which attacks cardamom incidentally, but a serious outbreak can do a great deal of damage. Collection and destruction of the pupae assists in control, as does spraying the plants with insecticides. A number of borers attack cardamom: the weevil Prodioctes haematicus bores into the rhizomes; the shoot and capsule borer Dichocrosis punctiferalis is one of the commonest stem borers in the tropics, affecting not only cardamom, but also castor, ginger and turmeric; the pod borer Lampides elpis is a minor pest; the tingid bug Stephanitis typicus may breed in numbers on cardamom leaves; there are records of attacks by some unidentified root borers and a number of polyphagous coccids and lepidopterous larvae. Damage is frequently caused by rats, monkeys, porcupines, wild pigs and birds.

Harvesting

Fruits are picked when fully developed but still green. For quality it is important that the seeds within the green pods have changed colour from white to brown or black. Fully ripe fruits tend to split on drying and do not give a good colour when dry, whereas small immature fruits result in an uneven, shrivelled and badly coloured appearance. Because the fruits ripen very irregularly, they should be harvested individually at the correct stage of ripeness. They also need to be picked with care so that they are not bruised or broken. In spite of the very uneven ripening, it may be advantageous to cut whole spikes, sacrificing the very immature fruits to get the others in the best possible condition.

Yield

The first small crop of cardamom is usually obtained in the third year after field planting (4-5 years after sowing). Higher yields are obtained in subsequent years continuing till the plants are 10-15 years old. The average yield of dry capsules from a well-maintained cardamom plantation may reach 110-170 kg/ha, but 45-80 kg/ha would represent the more usual level.

Handling after harvest

In the usual procedure, the freshly picked green cardamom fruits are first washed to free them from adhering dirt, then the stalks are clipped off with scissors. There are several ways of drying the fruit to reduce the moisture content from about 75% at harvest to 13% for safe storage. Green fruits are usually flue-cured in special curing rooms to arrest vegetative development and fix the green colour. Sun-drying is common practice, sometimes followed by bleaching in sulphur fumes. The main resulting quality categories are: whole green cardamom (flue-cured), whole bleached cardamom (sun-dried and bleached), whole straw-coloured cardamom (sun-dried), decorticated seeds (resulting from poor processing). The market deals in cardamom under names referring to appearance rather than origin. Packing methods must take into account the requirements for quality preservation during storage, and are based on controlling the moisture content, and the avoidance of physical damage and excessive heat. In the case of green cardamom, light must also be excluded. Green cardamom should be packed in wooden boxes or tins lined with heavy-gauge black polythene, metal foil or waterproof paper. Grinding almost exclusively takes place in the consuming countries.

Cardamom oil is produced commercially by steam distillation of crushed fruits. In general, recently harvested cardamom which has not suffered excessive essential-oil loss should be employed in order to obtain a good yield. Complete distillation is necessary to obtain the full flavour character of the oil (at least 4 hours distillation to produce the full ester content of the oil). Cardamom oil deteriorates in storage, not because of evaporation losses as is the case with the spice, but because of chemical transformations.

Cardamom oleoresin is produced on a relatively small scale. Solvent extraction yield is about 10%, the essential-oil content ranges from 50-60%, and the replacement strength is about 1 kg of oleoresin to 20 kg of the ground spice.

Genetic resources

A collection of cardamom germplasm is maintained by the Research Institute for Spice and Medicinal Crops, Bogor, Indonesia. A large germplasm collection is maintained by the National Repository of Plant Genetic Resources in Idukki, India.

Breeding

Considerable variation occurs in cardamom, because it is cross-pollinated. Some selection work is being performed in India. Several high-yielding cultivars have been released (ICRI-1, ICRI-2, ICRI-3, ICRI-4). Careful screening of single plant selections made from indigenous cardamom, and subsequent cloning, will lead to improved planting materials, capable of outyielding the cultivated bulk cardamom. Resistance to katte mosaic and thrips should be sought by hybridization, followed by clonal propagation.

Prospects

True cardamom and its derived products have a secure market without much prospect of dramatic changes. World trade in true cardamom shows a fairly small, but steady long-term growth in consumption. However, cardamom seems to be very vulnerable to diseases and pests.

Literature

• Burtt, B.L. & Smith, R.M., 1983. Zingiberaceae. Elettaria. In: Dassanayake, M.D. & Fosberg, F.R. (Editors): A revised handbook to the flora of Ceylon. Vol. 4. Amerind Publishing Co., New Delhi, India. pp. 528-530.
• Kumaresan, D., Regupathy, A. & Baskaran, P., 1988. Pests of spices. Rajalakshmi Publications, Nagercoil, Tamil Nadu, India. 141 pp.
• Lewis, Y.S., Nambudri, E.S. & Philip, T., 1966. Composition of cardamom oils. Perfum. essent. Oil Rec. 57: 623-628.
• Nair, M.R.G.K., 1978. Cardamom. In: A monograph on crop pests of Kerala and their control. Kerala Agricultural University Vellanikkara, Kerala, India. pp. 65-74.
• Parameswar, N.S., 1973. Floral biology of cardamom (Elettaria cardamomum Maton). Mysore Journal of Agricultural Science 7: 205-213.
• Purseglove, J.W., Brown, E.G., Green, C.L. & Robbins, S.R.J., 1981. Spices. Vol. 2. Longman, Harlow, Essex, United Kingdom. pp. 581-643.
• Samarawira, I., 1972. Cardamom. World Crops 24(2): 76-78.
• Shankaracharya, N.B. & Natarajan, C.P., 1971. Cardamom: chemistry, technology and uses. Indian Food Packer 25: 28-36.
• Suratman, Djauhariya, E. & Sudiarto, 1987. Plasma nutfah kapulaga [Cardamom germplasm]. Edisi Khusus Penelitian Tanaman Rempah dan Obat 3(1): 64-69.

Sources of illustrations

Koorders, S.H., 1913. Exkursionsflora von Java [Excursion flora of Java]. Vol. 4. Atlas. Gustav Fischer Verlag, Jena, Germany. Fig. 566, p. 320 (leaf); Schumann, K., 1904. Zingiberaceae. In: Engler, A. (Editor): Das Pflanzenreich [The plant kingdom]. Vol. 4, Fam. 46. W. Engelmann, Leipzig, Germany. Fig. 33, p. 268 (inflorescence, flower, fruits, seed with aril); Lewis, Y.S., 1984. Spices and herbs for the food industry. Food Trade Press, Orpington, United Kingdom. Photograph, p. 48 (habit fruiting clump). Redrawn and adapted by P. Verheij-Hayes.

Authors

• T.H. Wardini & A. Thomas