Carum carvi (PROSEA)
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Introduction |
Carum carvi L.
- Protologue: Sp. pl.: 263 (1753).
- Family: Umbelliferae
- Chromosome number: 2n = 20
Synonyms
- Carum velenovskyi Rohlena (1903)
Vernacular names
- Caraway (En).
- Carvi (Fr)
- Thailand: hom-pom (northern)
Origin and distribution
The species consists of a winter (biennial) and a spring (annual) type. The latter is indigenous to the eastern part of the Mediterranean including Egypt. The winter type is native to the mountain ranges of Eurasia and along the draining rivers flowing from them. It is cultivated in East-European countries and the Netherlands.
Unless otherwise specified it is the spring type that is described and referred to below, because of its relevance for South-East Asia.
Uses
The small dried caraway fruit, an achene usually referred to as seed, has a characteristic distinct taste and pleasant smell, and is mainly used as a spice. It is one of the spicy fruits of Indian cooking. In large parts of Europe and northern America the whole fruit is used in bakery products, and for flavouring meat and various dishes.
An essential oil is obtained by steam distillation from the fruits. The oil is extensively used as a flavour component in major food products, including alcoholic (e.g. the well-known Scandinavian Akvavit) and non-alcoholic beverages, in cosmetic products such as soap, perfume and toothpaste, and in pharmaceutical preparations. In the United States the regulatory status "generally recognized as safe" has been accorded to caraway (GRAS 2236) and caraway fruit oil (GRAS 2238). The maximum permitted level for caraway oil in food products is about 0.02%. Consumption of caraway enhances lactation of breast-feeding women. Caraway fruit and the oil are regarded medicinally as carminative and stomachic. The activity of the essential oil in a daily dose of 3-6 drops is spasmolytic, anti-microbial, and it is applied for dyspeptic complaints such as mild gastro-intestinal spasm, bloating and fullness. These qualities are attributed to the major component of the oil, carvone. Carvone has been shown to possess certain cancer-preventive properties. It is also effective as an anti-sprouting agent in stored consumption potatoes and seed potatoes, controlling most storage fungi at the same time. It is also used as disinfectant and as insect repellant. In Germany caraway plants with immature fruits are a highly regarded component in herbal meadows, producing herbal hay enhancing lactation in dairy cattle.
Production and international trade
As it is a world market commodity, market forces determine the price of caraway. Since the market is usually oversupplied, caraway prices are chronically low. In times of scarcity prices increase rapidly and quite dramatically. Subsequently, production areas increase, resulting in overproduction. At the same time, in traditional areas, much of the fruit is home-grown or collected in the wild.
The major producers of winter-type caraway are the Netherlands, Poland, Hungary and Russia. The spring type is produced in Egypt and western India.
The United States is a major importer of caraway fruit and oil, with average annual imports in the early 1990s of 3000 t fruit and 4 t oil. In the United States the price of 1 kg of fruits is about US$ 1, of 1 kg oil US$ 33. Average annual world production of caraway oil is estimated at 30 t, with a total value of about US$ 1 million.
Properties
Per 100 g edible portion dried caraway fruits contain: water 10 g, protein 20 g, fat 14 g, carbohydrates 37 g, fibre 13 g, ash 6 g (Ca 689 mg, Fe 16 mg, Mg 258 mg, P 568 mg, K 1.4 g, Na 17 mg, Zn 6 mg), vitamin A 363 IU. The energy value is about 1395 kJ/100 g.
Carefully produced caraway fruit of the spring (annual) type, airdried to 10-12% moisture, contains 1.5-5.0% of caraway essential oil, depending on year and soil conditions; 1000-fruit weight is 4-5 g. Fruit of the winter (biennial) type has a content of 3.0-7.0% oil, depending on year of production and time of harvesting: early harvesting gives a slightly smaller fruit and a higher oil content; 1000-fruit weight is 3.0-4.5 g. On account of its superior oil content the biennial fruit has the better quality, i.e. a stonger taste.
The oil consists largely of two monoterpenic components: d-carvone or S-(+)-carvone (45-60%) and d-limonene or S-(+)-limonene (35-55%). d-Carvone is responsible for the characteristic flavour and biological properties.
The stereoisomer L-(-)-carvone occurs in the sapodilla or chicle-tree fruit (Manilkara zapota (L.) P. van Royen) of South America and has a quite different taste.
Unlike dill (Anethum graveolens L.), the other plant parts of caraway do not contain carvone or limonene.
A monograph on the physiological properties of caraway oil has been published by the Research Institute for Fragrance Materials (RIFM).
Composition
Caraway oil (from Israel) (Source: Putievsky et al., 1994)
- 49.0% carvone
- 48.0% limonene
- 0.4% myrcene
- 0.3% trans-carveol
- 0.3% trans-dihydrocarvone
- 0.2% dihydrocarveol
- 0.1% cis-dihydrocarvone
- 0.1% cis-carveol
- 0.1% β-caryophyllene
- 0.1% linalool
- 0.1% α-pinene
- 0.1% sabinene
- 0.1% β-phellandrene
- trace α-terpinene
- trace β-pinene
- trace camphene
- trace para-cymene
- trace terpinolene
- 98.8% total
Caraway oil (from France) (Source: Bourrel et al., 1995)
- 50.1% carvone
- 45.4% limonene
- 1.4% dihydrocarveol
- 1.0% dihydrocarvone
- 0.3% myrcene
- 0.3% trans-carveol
- 0.2% para-cymene
- 0.2% p-mentha-1,3-dien-7-al
- 0.1% γ-terpinene
- 0.1% sabinene
- trace α-pinene
- 99.1% total
Adulterations and substitutes
Oil from the fruit of dill contains 20-50% d-carvone, and could serve as a substitute for caraway oil. Caraway oil often is adulterated with synthetic d-carvone.
Description
- A glabrous, erect, annual or biennial herb, 0.5-1.5 m tall. Taproot fusiform to cylindrical, strong, thick, fleshy and long. Stem terete, up to 2 cm in diameter, hollow, striate, branching in upper part.
- Leaves alternate, in approximately 2/5 arrangement, compound, bright green; petiole up to 13 cm long, upper ones gradually shorter, uppermost absent, all of them with a sheath with membranous margin and auriculate apex; blade subtriangular in outline, 6-15 cm × 2-8 cm, 2-3-pinnate, lowest leaf segments at least twice as long as wide, ultimate lobes linear-lanceolate to linear, 3-25 mm long.
- Inflorescence a compound umbel, 4-8 cm in diameter, terminal; peduncle up to 11 cm long; bracts and bracteoles absent or few, bracts occasionally leaf-like; primary rays 3-16, unequal, 0.5-6 cm long; secondary rays 6-16, unequal, up to 1 cm long; umbellets about 1 cm in diameter.
- Flowers bisexual, protandrous, usually white, sometimes pinkish; calyx absent; petals 5, obcordate with short inflexed apex, about 1.5 mm × 1 mm; stamens 5; styles 2, recurved, with enlarged base forming the stylopodium, stigma capitate.
- Fruit a schizocarp, ellipsoidal, laterally compressed, 3-5 mm long, splitting into 2 mericarps; mericarp often falcate, 5-ribbed, brown, with wide, solitary vittae.
Growth and development
Germination of the seed is immediate but growth of the tiny seedlings is rather slow. Seed dormancy can cause problems in Mediterranean countries. In the Netherlands flower initiation of the spring type starts 6-12 weeks after sowing, with another 4-8 weeks to maturity. The sequence of flowering in umbels and umbellets is from the outside to the inside. The inner umbellets and the latest formed umbels tend to produce predominantly male flowers. In bisexual flowers protandry is the rule and hence the plants must cross-fertilize, pollen being carried by wind and insects. Dry, sunny weather is optimal for insect activity and also for pollen dissemination, and thus for good seed set.
Other botanical information
There do not seem to be any vernacular names for caraway in any of the South-East Asian countries. Burkill is the only author to mention "jintan” as a Malay name for caraway; however, his description of caraway contains information derived from cumin (Cuminum cyminum L.). The fruit of the two crops is very similar in outward appearance and may easily be confused. If in doubt, bite the fruit, the taste is very different and distinctive. Jintan is clearly cumin, usually in the form of ground fruit. Caraway fruit is not marketed in ground form.
The two major cultivars of winter caraway in the Netherlands are "Volhouden" and "Bleija". "Volhouden" shatters its fruits easily at maturity, necessitating swathing prior to harvesting so as to reduce the risk of considerable losses at harvesting. However, threshing and cleaning is easy, and its fruit is well suited for use as a spice. "Bleija" fruits are non-shattering, giving better yield security, but usually two rounds of threshing are required to get rid of fruit stalks.
Two cultivars of spring caraway have been commercially released in the Netherlands: "Karzo" and "Springcar", both with a non-shattering fruit.
Northern Eurasian winters are sufficiently protracted to vernalize winter caraway plants, provided the plants are of a sufficient size, i.e. have grown a taproot of at least 8 mm in diameter. Such plants require 6-8 weeks exposure to temperatures below 10 °C.
Ecology
Spring caraway thrives in the cool short days of the eastern Mediterranean winter and of the Indian plains. Biennial winter caraway occurs naturally in meadows, grassland, forest edges, along roads and rivers and as a weed in fields, from sea-level up to 4000 m altitude.
Propagation and planting
Caraway is propagated by seed. The small seed requires an even, well-prepared seedbed. Seed is sown about 1-2 cm deep in rows 20-30 cm apart, or broadcast at a rate of 5-10 kg/ha. In Israel, a plant stand of 60 per m2 gives the best per ha yield.
Micropropagation using in vitro culture of tissues derived from petiole, hypocotyl and seedling shoot tip has been reported.
Husbandry
Weeding is recommended during establishment of the crop. Application of 75-100 kg N/ha is recommended to stimulate root development.
Diseases and pests
In the Netherlands, the main disease of spring caraway is the soilborne Sclerotinia stem rot, which can only be controlled by wide crop rotation. As concerns potential insect pests, the carrot fly attacks caraway roots. Birds and mice can be major pests.
Harvesting
The crop may be left to die and dry in the field prior to harvesting, unless the cultivar has shattering fruit.
Yield
Yields in the Netherlands are in the order of 1.0-1.8 t/ha.
Handling after harvest
Threshing should be done with care, to ensure that stalks and other materials are properly removed from the fruits, since the trade is very strict in this respect. The fruits should be dried (in the air or artificially at 30 °C) to a moisture content of about 12%. The fruit stores and transports very well.
The essential oil is commercially extracted from the fruit by super-heated steam.
Genetic resources
Accessions of spring caraway may be available from the national gene banks of Egypt and Israel. A few are in the Netherlands gene bank.
Breeding
Since caraway is basically outbreeding, recurrent population improvement is basic for seed breeding. Limited breeding work is in progress in Egypt and Israel. Breeding annual cultivars adapted to European spring and summer conditions yielded the Dutch cultivars Karzo and Springcar.
Prospects
Unless there is a breakthrough in the market, such as the regular use of carvone from caraway fruit in the agriculture and pharmaceutical industries, the continued overproduction and chronically low prices will remain a disincentive to invest in crop improvement. However, limited cultivation of an annual caraway cultivar locally adapted to the cooler climates of the mountainous zones in South-East Asia may supply the local medicinal and culinary demand, which is currently met from Indian sources. At the same time, caraway with its distinct flavour may in due course be a stimulating addition to the existing range of spices available in South-East Asia.
Literature
- Furmanowa, M., Sowinska, D. & Pietrosiuk, A., 1991. Carum carvi L. (caraway): in vitro culture, embryogenesis, and the production of aromatic compounds. In: Bajaj, Y.P.S. (Editor): Biotechnology in agriculture and forestry 15. Medicinal and aromatic plants III. Springer Verlag, Berlin, Germany. pp. 176-192.
- Németh, E. (Editor), 1998. Caraway - the genus Carum. Medicinal and aromatic plants - Industrial profiles. Harwood Academic Publishers, Amsterdam, the Netherlands. 200 pp.
- Toxopeus, H. & Bouwmeester, H.J., 1993. Improvement of caraway essential oil and carvone production in the Netherlands. Industrial Crops and Products 1: 295-301.
- van Steenis, C.G.G.J. (Editor), 1949. Flora Malesiana. Series I. Volume 4. Kluwer Academic Publishers, Dordrecht, the Netherlands. p. 133.
- Wander, J.G.N., 1994. Teelt van karwij [Cultivation of caraway]. Teelthandleiding No 60. Proefstation voor de Akkerbouw en de Groenteteelt in de Vollegrond, Lelystad, the Netherlands. 32 pp.
Sources of illustrations
Ross-Craig, S., 1958. Drawings of British Plants. Part 12. Umbelliferae. G. Bell & Sons, London, United Kingdom. Plate 19. Redrawn and adapted by P. Verheij-Hayes.
Authors
- H. Toxopeus & J.H. Lubberts
