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| Plate XXI: CITRON, Citrus medica |
The citron is borne by a slow-growing shrub or small tree reaching 8 to 15 ft (2.4-4.5 m) high with stiff branches and stiff twigs and short or long spines in the leaf axils. The leaflets are evergreen, lemon-scented, ovate-lanceolate or ovate elliptic, 2 1/2 to 7 in (6.25-18 cm) long; leathery, with short, wingless or nearly wingless petioles; the flower buds are large and white or purplish; the fragrant flowers about 1 1/2 in (4 cm) wide, in short clusters, are mostly perfect but some male because of pistil abortion; 4- to 5-petalled, often pinkish or purplish on the outside, with 30 to 60 stamens. The fruit is fragrant, mostly oblong, obovoid or oval, occasionally pyriform, but highly variable; various shapes and smooth or rough fruits sometimes occurring on the same branch; one form is deeply divided from the apex into slender sections; frequently there is a protruding style; size also varies greatly from 3 1/2 to 9 in or even 1 ft (9-22.8 or 30 cm) long; peel is yellow when fully ripe; usually rough and bumpy but sometimes smooth; mostly very thick, fleshy, tightly clinging; pulp pale-yellow or greenish divided into as many as 14 or 15 segments, firm, not very juicy, acid or sweet; contains numerous monoembryonic seeds, ovoid, smooth, white within.
The citron's place of origin is unknown but seeds were found in Mesopotamian excavations dating back to 4000 B.C. The armies of Alexander the Great are thought to have carried the citron to the Mediterranean region about 300 B.C. A Jewish coin struck in 136 B.C. bore a representation of the citron on one side. A Chinese writer in AD 300 spoke of a gift of "40 Chinese bushels of citrons from Ta-ch'in" in AD 284. Ta-ch'in is understood to mean the Roman Empire. The citron was a staple, commercial food item in Rome in AD 301. There are wild citron trees in Chittagong, Sitakund Hill, Khasi and Garo hills of northern India. Dioscorides mentioned citron in the 1st Century AD and Pliny called it malus medica, malus Assyria and citrus in AD 177. The fruit was imported into Greece from Persia (now Iran). Greek colonists began growing the citron in Palestine about 200 B.C. The tree is assumed to have been successfully introduced into Italy in the 3rd Century. The trees were mostly destroyed by barbarians in the 4th Century but those in the "Kingdom of Naples" and in Sardinia and Sicily survived. By the year 1003, the citron was commonly cultivated at Salerno and fruits (called poma cedrina) were presented as a token of gratitude to Norman lords. For centuries, this area supplied citron to the Jews in Italy, France and Germany for their Feast of the Tabernacles (sukkot) ceremony. Moses had specified the cone of the cedar, hadar (kedros in Greek) and when it fell into disfavor it was replaced by the citron, and the Palestine Greeks called the latter kedromelon (cedar apple). Kedros was Latinized as cedrus and this evolved into citrus, and subsequently into citron. For many years, most Citrus species were identified as botanical varieties of Citrus medica.
Spaniards probably brought the citron with other Citrus species to St. Augustine, Florida, though it could have survived there only in greenhouses. The tree was introduced into Puerto Rico in 1640. Commercial citron culture and processing began in California in 1880. The trees suffered severe cold damage in 1913 and, within a few years, the project was abandoned. From 1926 to 1936, there were scattered small plantings of citron in Florida, and particularly one on Terra Ceia Island, supplying fruits to the Hills Brothers Canning Company. The groves eventually succumbed to cold and today the citron is grown in southern Florida only occasionally as a curiosity. The main producing areas of citron for food use are Sicily, Corsica and Crete and other islands off the coasts of Italy, Greece and France, and the neighboring mainland. Citron is also grown commercially in the central, mountainous coffee regions of Puerto Rico. Some is candied locally but most is shipped in brine to the United States and Europe. Citron is casually grown in several other islands of the Caribbean and in Central and South America. It has been rather commonly grown in Brazil for many years. There have long been scattered citron trees in the Cauca Valley of Colombia. After 5 years of study, horticulturists decided in 1964 that commercial culture could be profitable. Citron trees are not uncommon in some of the Pacific Islands but are rare in the Philippines.
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| Plate XXII: FINGERED CITRON, Citrus medica var. sarcodactylus |
Citron cultivars are mainly of two types: 1) those with pinkish new growth, purple flower buds and purple-tinted petals, acid pulp and dark inner seed coat and chalazal spot; 2) those with no pink or purple tint in the new growth nor the flowers, with non-acid pulp, colorless inner seed coat, and pale-yellow chalazal spot. Among the better-known cultivars are:
'Corsican'–origin unknown but the leading citron of Corsica; introduced into the United States around 1891 and apparently the cultivar grown in California; ellipsoid or faintly obovate, furrowed at base; large; peel yellow, rough, lumpy, very thick, fleshy; pulp crisp, non-juicy, non-acid, seedy. Tree small, spreading, moderately thorny with some large spines.
'Diamante' ('Cedro Liscio'; possibly the same as 'Italian' and 'Sicilian')–of unknown origin but the leading cultivar in Italy and preferred by processor's elsewhere; long-oval or ellipsoid, furrowed at base, broadly nippled at apex; peel yellow, smooth or faintly ribbed; very thick, fleshy; pulp crisp, non-juicy, acid; seedy. Tree small, spreading, thorny as 'Corsican'. Very similar is a cultivar called "Earle" in Cuba.
'Etrog' ('Ethrog', 'Atrog'; C. medica var. Ethrog Engl.)–the leading cultivar in Israel; ellipsoid, spindle-shaped or lemon-like with moderate neck and often with persistent style at base; usually with prominent nipple at apex; medium-small as harvested; if not picked early, it will remain on the tree, continuing to enlarge for years until the branch cannot support it. For ritual use, the fruit should be about 5 oz (142 g) and not oblong in form. Peel is yellow, semi-rough and bumpy, faintly ribbed, thick, fleshy; flesh is crisp, firm, with little juice; acid; seedy. Tree is small, not vigorous; leaves rounded at apex and cupped. This cultivar has been the official citron for use in the Feast of the Tabernacles ritual but if unavailable any yellow, unblemished, lemon-sized citron with adhering style can be substituted.
'Fingered Citron', Plate XXI, ('Buddha's Hand', or 'Buddha's Fingers'; C. medica var. sarcodactylus Swing.); called fu shou in China, bushukon in Japan, limau jari, jeruk tangan, limau kerat lingtang, in Malaya; djerook tangan in Indonesia; som-mu in Thailand; phât thu in Vietnam. The fruit is corrugated, wholly or partly split into about 5 finger-like segments, with little or no flesh; seedless or with loose seeds. The fruit is highly fragrant and is placed as an offering on temple altars. It is commonly grown in China and Japan; is candied in China.
In India, there are several named types, in addition to the 'Fingered', in the northwest:
'Bajoura'–small, with thin peel, much acid juice.
'Chhangura'–believed to be the wild form and commonly found in a natural state; fruit rough, small, without pulp.
'Madhankri' or 'Madhkunkur'–fruit large with sweetish pulp.
'Turunj'–fruit large, with thick peel, the white inner part sweet and edible; pulp scant, dry, acid. Leaves are oblong and distinctly notched at the apex.
The citron tree is highly sensitive to frost; does not enter winter dormancy as early as other Citrus species. Foliage and fruit easily damaged by very intense heat and drought. Best citron locations are those where there are no extremes of temperature.
The soils where the citron is grown vary considerably, but the tree requires good aeration.
Citron trees are grown readily from cuttings taken from branches 2 to 4 years old and quickly buried deeply in soil without defoliation. For quicker growth, the citron may be budded onto rough lemon, grapefruit, sour orange or sweet orange but the fruits do not attain the size of those produced from cuttings, and the citron tends to overgrow the rootstock. Rough lemon has been found too susceptible to gummosis to be employed as a rootstock for citron in Colombia. The 'Etrog', to be acceptable for ritual use, must not be budded or grafted.
The citron tree tends to put out water sprouts that should be eliminated, and the grower should prune branches hanging so low that they touch the ground with the weight of the fruit. Italian producers keep the tree low and stake the branches, and may even trim off the thorns, to avoid scarring of the fruits. The trees begin to bear when 3 years old and reach peak production in 15 years; die in about 25 years.
In 'Etrog' orchards, the Israeli growers are careful to take every precaution to protect the fruit, tying the fruiting branch securely in place and trimming away any twigs that might touch the fruit. To avoid moving irrigation equipment through the groves, the trees are manually watered and frequently sprayed to eliminate destructive insects.
If citrons are allowed to fully ripen on the tree they will be very aromatic and the peel yellow, the inner peel very tender. In India, a fruiting branch may be bent down and the immature fruit put into a jar shaped like a human head (or other form) so that the mature fruit will be of the same shape. These are sold as curiosities and are said to be intensely fragrant.
The citron tree blooms nearly all year, but mostly in spring and the spring blooms produce the major part of the crop. The fruit is dark-green when young, takes 3 months to turn yellow. To retain the green color, firmness and uniformity desired by the dealers in candied citron, the fruit must be picked when only 5 to 6 in (12.5-15 cm) long and 3 to 4 in (7.5-10 cm) wide. Mature trees yield an average of 66 lbs (30 kg) per year but exceptional trees have borne as much as 150 to 220 lbs (68-100 kg). 'Etrog' fruits are wrapped in hemp fiber immediately after picking. Those for local use are inspected by rabbis, and those for export by agents of the Ministry of Agriculture.
The citron tree is undoubtedly subject to most of the pests that attack other Citrus species. The citrus bud mite (Eriophyes sheldoni), citrus rust mite (Phyllocoptruta oleivora), and snow scale (Unaspis citri) are among its major enemies.
Horticulturists in Florida report that citron trees in this state are nearly always unthrifty, are subject to gummosis, and usually in a state of decline and dieback, and are accordingly poor bearers.
Branch knot, caused by the fungus Sphaeropsis tumefaciens, was first noticed on citron trees in Puerto Rico in 1977. By 1983, it had become a serious threat to the local citron industry. The deformations become large and necrotic, lead to witches' broom, dieback and breaking of branches.
The most important part of the citron is the peel which is a fairly important article in international trade. The fruits are halved, depulped, immersed in seawater or ordinary salt water to ferment for about 40 days, the brine being changed every 2 weeks; rinsed, put in denser brine in wooden barrels for storage and for export. After partial de-salting and boiling to soften the peel, it is candied in a strong sucrose/glucose solution. The candied peel is sun-dried or put up in jars for future use. Candying is done mainly in England, France and the United States. The candied peel is widely employed in the food industry, especially as an ingredient in fruit cake, plum pudding, buns, sweet rolls and candy.
Puerto Rican food technologists reported in 1970 that the desalted citron could be dehydrated in a hot air tray dryer at 108º F (42.22º C), reducing the weight by 95% to lower costs of shipment, then stored in polyethylene bags and later reconstituted and candied. In 1979, after further experiments, it was announced that fresh citron cubes, blanched for 1/2 minute in water at 170º F (76.7º C) can be candied and the product is equal in quality to the brined and candied peel, and this procedure saves the costs of salt, storage, and shipping of heavy barrels. If the citron lacks flavor, a few orange or lemon leaves may be added to the sirup.
The fruit of the wild 'Chhangura' is pickled in India. In Indonesia, citron peel is eaten raw with rice. The entire fruit of the 'Fingered citron' is eaten.
If there is sufficient juice in the better cultivars, it is utilized for beverages and to make desserts. In Guatemala, it is used as flavoring for carbonated soft-drinks. In Malaya, citron juice is used as a substitute for the juice of imported, expensive lemons. A product called "citron water" is made in Barbados and shipped to France for flavoring wine and vermouth.
In order to expand the market for citron, Puerto Rican workers have established that the green-mature fruits can be peeled by immersing in a boiling lye solution to save the labor of hand-peeling and then the fruits can be made into marmalade, jelly, and fruit bars that are crusty on the outside, soft within.
In Spain, a sirup made from the peel is used to flavor unpalatable medical preparations.
Food Value Per 100 g of Edible Portion*
| Moisture | 87.1 g |
| Protein | 0.081 g |
| Fat | 0.04 g |
| Fiber | 1.1 g |
| Ash | 0.41 g |
| Calcium | 36.5 mg |
| Phosphorus | 16.0 mg |
| Iron | 0.55 mg |
| Carotene | 0.009 mg |
| Thiamine | 0.052 mg |
| Riboflavin | 0.029 mg |
| Niacin | 0.125 mg |
| Ascorbic Acid | 368 mg |
Fruit: Chinese and Japanese people prize the citron for its fragrance and it is a common practice in central and northern China to carry a ripe fruit in the hand or place the fruit in a dish on a table to perfume the air of a room. The dried fruits are put with stored clothing to repel moths. In southern China, the juice is used to wash fine linen. Formerly, the essential oil was distilled from the peel for use in perfumery.
Leaves and twigs: In some of the South Pacific islands, "Cedrat Petitgrain Oil" is distilled from the leaves and twigs of citron trees for the French perfume industry.
Flowers: The flowers have been distilled for essential oil which has limited use in scent manufacturing.
Wood: Branches of the citron tree are used as walking-sticks in India. The wood is white, rather hard and heavy, and of fine grain. In India, it is used for agricultural implements.
Medicinal Uses: In ancient times and in the Middle Ages, the 'Etrog' was employed as a remedy for seasickness, pulmonary troubles, intestinal ailments and other disorders. Citron juice with wine was considered an effective purgative to rid the system of poison. In India, the peel is a remedy for dysentery and is eaten to overcome halitosis. The distilled juice is given as a sedative. The candied peel is sold in China as a stomachic, stimulant, expectorant and tonic. In West Tropical Africa, the citron is used only as a medicine, particularly against rheumatism. The flowers are used medicinally by the Chinese. In Malaya, a decoction of the fruit is taken to drive off evil spirits. A decoction of the shoots of wild plants is administered to improve appetite, relieve stomachache and expel intestinal worms. The leaf juice, combined with that of Polygonum and Indigofera is taken after childbirth. A leaf infusion is given as an antispasmodic. In Southeast Asia, citron seeds are given as a vennifuge. In Panama, they are ground up and combined with other ingredients and given as an antidote for poison. The essential oil of the peel is regarded as an antibiotic.