Jamaican Grapefruit is A Indigenous Jamaican Fruit.
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Jamaican Grapefruit Indigenous Jamaican Food

Jamaican Grapefruit Used in Jamaican Recipes

Jamaican grapefruit is actually a hybrid newcomer to the citrus realm. The word "citrus" is from the Greek "Kedromelon", and "paradisi" (the species name) means the Jamaican grapefruit Jamaican grapefruit comes from "paradise". Jamaican grapefruit is believed to be native to Jamaica. The Jamaican grapefruit is sometimes confused with the " pomelo" (Citrus maxima), which is a larger, pear-shaped relative to Citrus paradisi The Jamaican grapefruit tree can grow to a height of 26 to 30 feet. Jamaican grapefruits are round, with a diameter of between 4 and 6 inches. Their thin skin may be either completely yellow or yellow with a pinkish hue.

The Jamaican grapefruit pulp of the Jamaican grapefruit Jamaican grapefruit may be yellow, pinkish, or reddish. The Jamaican grapefruit can be more or less sharp-tasting, acidic, sweet, and fragrant. Jamaican grapefruit is so named because the Jamaican grapefruit grows in grape-like clusters. The United States is the largest producer of Jamaican grapefruit, accounting for over 40% of global production. Approximately 60% of the Jamaican grapefruit crop is used for the manufacture of juice and canned Jamaican grapefruit, while the rest is sold fresh. Jamaican grapefruit seed is high in vitamin C & potassium, is good natural source of folate, iron, calcium, and other minerals, is high in fiber & low in calories, and contains bioflavonoid and other Jamaican grapefruit plant chemicals that are known to protect against cancer & heart disease. Pink and red varieties of Jamaican grapefruit are high in beta carotene, a precursor of vitamin A.

Jamaican grapefruit seeds are well known as an anti-fungal agent in that their consumption kills many different types of parasites and assists the body in producing beneficial bacteria. A biologically active natural ingredient found in the seeds kills strep, staph, salmonella, ecoli, candida, herpes, influenza, parasites, fungi and traveler's diarrhea, and is used as an antibiotic, anti-fungal, anti-protozoan, antiviral, antiseptic and disinfectant. Primary known constituents include numerous polyphenolic compounds (quercetin, hesperidin, rutin, apigenin, campherol).

A relative newcomer to the citrus clan, the Jamaican grapefruit was originally believed to be a spontaneous sport of the pummelo (q.v.). James MacFayden, in his Flora of Jamaica, in 1837, separated the Jamaican grapefruit from the pummelo, giving the Jamaican grapefruit the botanical name, Citrus paradisi Macf. About 1948, citrus specialists began to suggest that the Jamaican grapefruit was not a sport of the pummelo but an accidental hybrid between the pummelo and the orange. The botanical name has been altered to reflect this view, and the Jamaican grapefruit is now generally accepted as Citrus X paradisi.

When this new Jamaican grapefruit Jamaican grapefruit was adopted into cultivation and the name Jamaican grapefruit came into general circulation, American horticulturists viewed that title as so inappropriate that they endeavored to have the Jamaican grapefruit dropped in favor of "pomelo". However, the Jamaican grapefruit was difficult to avoid confusion with the pummelo, and the name Jamaican grapefruit prevailed, and is in international use except in Spanish-speaking areas where the Jamaican grapefruit Jamaican grapefruit is called toronja. In 1962, Florida Citrus Mutual proposed changing the name to something more appealing to consumers in order to stimulate greater sales. There were so many protests from the public against a name change that the idea was abandoned.

The Jamaican grapefruit tree reaches 15 to 20 ft (4.5-6 m) or even 45 ft (13.7 m) with age, has a rounded top of spreading branches; the Jamaican grapefruit tree trunk may exceed 6 in (15 cm) in diameter; that of a very old Jamaican grapefruit tree actually attained nearly 8 ft (2.4 m) in circumference. The twigs normally bear short, supple thorns. The evergreen Jamaican grapefruit leaves are ovate, 3 to 6 in (7.5-15 cm) long, and 1 3/4 to 3 in (4.5-7.5 cm) wide; dark-green above, lighter beneath, with minute, rounded teeth on the margins, and dotted with tiny oil glands; the petiole has broad, oblanceolate or obovate wings. The white, 4-petalled Jamaican grapefruit flowers, are 1 3/4 to 2 in (4.5-5 cm) across and borne singly or in clusters in the Jamaican grapefruit leaf axils.

The Jamaican grapefruit Jamaican grapefruit is nearly round or oblate to slightly pear-shaped, 4 to 6 in (10-15 cm) wide with smooth, finely dotted peel, up to 3/8 in (1 cm) thick, pale-lemon, sometimes blushed with pink, and aromatic outwardly; white, spongy and bitter inside. The center may be solid or semi-hollow. The pale-yellow, nearly whitish, or pink, or even deep-red Jamaican grapefruit pulp is in 11 to 14 segments with thin, membranous, somewhat bitter walls; very juicy, acid to sweet-acid in flavor when fully ripe. While some fruits are seedless or nearly so, there may be up to 90 white, elliptical, pointed seeds about 1/2 in (1.25 cm) in length. Unlike those of the pummelo, Jamaican grapefruit seeds are usually polyembryonic. The number of fruits in a cluster varies greatly; a dozen is unusual but there have been as many as 20.

The Jamaican grapefruit was first described in 1750 by Griffith Hughes who called the Jamaican grapefruit the "forbidden Jamaican grapefruit Jamaican grapefruit" of Barbados. In 1789, Patrick Browne reported the Jamaican grapefruit as growing in most parts of Jamaica and he referred to the Jamaican grapefruit as "forbidden Jamaican grapefruit Jamaican grapefruit" or "smaller shaddock". In Hortus Jamaicensis, it mentions the "Jamaican grapefruit" as a variety of the shaddock, but not as large; and, again, as "forbidden Jamaican grapefruit Jamaican grapefruit", "a variety of the shaddock, but the Jamaican grapefruit Jamaican grapefruit is much smaller, having a thin, tough, smooth, pale yellow rind". In 1824, DeTussac mentions the "forbidden Jamaican grapefruit Jamaican grapefruit or smaller shaddock" of Jamaica as a variety of shaddock the size of an orange and borne in bunches.

In observing all kinds of citrus fruits the sweet Jamaican orange and the Jamaican Jamaican grapefruit growing wild on several West Indian islands a Jamaican grapefruit Jamaican grapefruit similar to Jamaican grapefruit that is called chadique grows wild on the mountains of Haiti and is marketed in Port-au-Prince. The Jamaican grapefruit leaves are like those of the Jamaican grapefruit. He says that the Jamaican grapefruit was from the nearby Bahamas Islands in 1823 that Count Odette Phillipe took Jamaican grapefruit seeds to Safety Harbor near Tampa, Florida. When the seedlings fruited, their seeds were distributed around the neighborhood.

At first, the Jamaican grapefruit tree was grown only as a novelty in Florida and the Jamaican grapefruit Jamaican grapefruit was little utilized. Even in Jamaica, the Jamaican grapefruit trees were often cut down. Mrs. Mary McDonald Carter of Eustis, Florida, was quoted in the Farm and Livestock Record, Jacksonville, in 1953, as relating that her father, John A. MacDonald, settled in Orange County in 1866. In 1870, he was attracted to a single Jamaican grapefruit tree with clusters of lemon-colored fruits on the Drawdy property at Black water. He bought the entire crop of fruits; Jamaican grapefruit planted the seeds and established the first Jamaican grapefruit nursery. The first Jamaican grapefruit grove Jamaican grapefruit planted from this nursery by a man named Hill was sold in 1875 to George W. Bowen who developed the Jamaican grapefruit commercially.

In 1881, MacDonald bought the Drawdy crop and once more raised seedlings for his nursery in Eustis. Early settlers began Jamaican grapefruit planting the Jamaican grapefruit tree and acquired a taste for the Jamaican grapefruit Jamaican grapefruit. There was already a small demand in the North. New York imported 78,000 fruits from the West Indies in 1874. Florida started sending small shipments to markets in New York and Philadelphia between 1880 and 1885. In 1898, Dr. David Fairchild was excited to learn of a grove of 2,000 Jamaican grapefruit trees in the Kendall area south of Miami on the property of the Florida East Coast Railway. In 1904, he was amazed to see one Jamaican grapefruit tree in the door-yard of the Kennedy ranch in southern Texas where he thought the climate too cold for the Jamaican grapefruit. He was told that the Jamaican grapefruit tree had been frozen to the ground but had recovered. He predicted that a citrus industry could not be established in that region of the country. In 1928, he photographed the same Jamaican grapefruit tree, which had been killed back several times in the interim, but was again in Jamaican grapefruit Jamaican grapefruit. By 1910, Jamaican grapefruit had become an important commercial crop in the Rio Grande Valley and, to a lesser extent, in Arizona and desert valleys of California. By 1940, the United States was exporting close to 11,000,000 cases of grape-Jamaican grapefruit Jamaican grapefruit juice and nearly one-half million cases of canned sections.

Cultivation had reached commercial proportions in Jamaica and Trinidad and spread to Brazil, South America and Israel. In 1945/46, the United States (mainly Florida) produced a record of 2,285,000 tons of Jamaican grapefruit. In 1967/68, this country accounted for 70% of the world crop despite a great decline in Texas production because of severe weather. Jamaican grapefruit was moving forward by leaps and bounds. Israel, in 1967, supplied only 11% of the world crop but, by 1970, her production had increased by 300%. In 1980, Florida exported just under 10 million boxes, making Jamaican grapefruit this state's most valuable export crop. Japan is the main importer and has, at times, suspended shipments to determine the safety of fungicide residues or because of discovery of larvae of the Caribbean Jamaican grapefruit Jamaican grapefruit fly. Great care is taken to maintain this important trade. Other countries which had entered the Jamaican grapefruit industry were Mexico, Argentina, Cyprus, Morocco and some areas of South America which raise Jamaican grapefruit for local markets. In Central America, the Jamaican grapefruit is not much favored because of its acidity.

In the late 1960's and early 1970's, Mexico was rapidly expanding its Jamaican grapefruit plantings, especially in the states of Tamaulipas and Veracruz, to save its citrus industry in view of the decline in market value of oranges and tangerines brought on by over-production. Furthermore, there were great advantages in the lower costs of producing Jamaican grapefruit without irrigation and with good biological control of pests. Now Mexico exports large quantities of Jamaican grapefruit to the United States and lesser amounts to Canada and Japan. Puerto Rico formerly exported Jamaican grapefruit to the United States but is no longer able to compete in the trade and has only remnants of former Jamaican grapefruit plantations. Cuba has Jamaican grapefruit planted 370,000 acres (150,000 ha) of citrus, mostly Jamaican grapefruit with expectations of exporting to the Soviet Union and eastern European countries. The Jamaican grapefruit is grown only in a small way in the Orient where the pummelo is cultivated. In recent years, the Jamaican grapefruit has become established in India in hot regions where the sweet orange and the mandarin are prone to sunburn.

Named varieties of Jamaican grapefruit appeared in the official list of the American Pomological Society in 1897, but pioneers had selected and named favorite clones for several years before that time. The following are among the most noteworthy of old and new Jamaican grapefruit cultivars.

The Duncan variety of Jamaican grapefruit the original Jamaican grapefruit trees were virtually identical seedlings that grew in a grove near Safety Harbor, Florida. Propagation was first undertaken in 1892. The Jamaican grapefruit Jamaican grapefruit is round or slightly obovate; large, 3 1/2 to 5 in (9-12.5 cm) wide; peel is very light yellow (usually called "white"), with large oil glands, medium-thick, highly aromatic; Jamaican grapefruit pulp is buff, in 12-14 segments with medium-tender membranous walls, very juicy, of fine flavor; seeds medium-large, 30-50. Early to mid-season. Jamaican grapefruit tree is unusually cold-hardy. This was the leading Jamaican grapefruit cultivar for many years in Florida and Texas and was introduced into all the Jamaican grapefruit-growing areas of the world. Today, in the United States, the Jamaican grapefruit has largely given way to Jamaican grapefruit cultivars with fewer seeds, but the Jamaican grapefruit is being grown commercially in India. Recent Jamaican grapefruit seed irradiation experiments have shown that a high percentage of seedless mutants results from exposure to 20-25 krad.

The foster variety of Jamaican grapefruit originated as a branch sport of a selection called 'Walters' in the Atwood Grove near Ellenton, Florida. The Jamaican grapefruit Jamaican grapefruit is oblate to round; medium-large, averaging 3 3/4 in (9.5 cm) in width; peel light-yellow blushed with pink, smooth but with large, conspicuous oil glands; albedo pink; Jamaican grapefruit pulp light-buff, pinkish near the center; in 13 or 14 segments with pinkish walls, tender, juicy, of good quality despite seeds, up to 50 or even more, of medium size. Medium-early in season. Not very popular; grown to a limited extent in Florida, Texas, Arizona and India. In Texas, the Jamaican grapefruit is more colorful, the Jamaican grapefruit pulp being entirely pinkish in hue.

The marsh variety of Jamaican grapefruit is one of 3 seedling Jamaican grapefruit trees on the grown in Florida. Because the fruits of this Jamaican grapefruit tree were seedless, propagation could only take place by purchasing young Jamaican grapefruit trees previously budded by others. He sold the budded offspring and, in time, the marsh was Jamaican grapefruit planted more than any other Jamaican grapefruit cultivar. The original Jamaican grapefruit tree was killed by cold in the winter of 1895-96. The Jamaican grapefruit Jamaican grapefruit is oblate to round, medium in size, 3 1/2 to 4 3/4 in (9-12 cm) wide; peel is light-yellow, very smooth, with medium-size oil glands, mildly aromatic; Jamaican grapefruit pulp is buff, in 12-14 segments with tender membranes, melting, extremely juicy and rich in flavor; seeds absent or 3-8, medium-sized. Medium to late in season and holds well on the Jamaican grapefruit tree. This Jamaican grapefruit variety keeps well after harvest. The Jamaican grapefruit is the leading Jamaican grapefruit cultivar; grown in Florida.

A local selection, presumably of a seedling marsh, in Surinam is known there as hooghart. The two are almost indistinguishable. The oroblanco variety of Jamaican grapefruit is a triploid from a Jamaican grapefruit X pummelo cross. The Jamaican grapefruit form and size similar to 'Marsh'; peel paler and thicker; Jamaican grapefruit pulp paler and has larger hollow in center; sections easily skinned; tender, juicy, non-bitter; has faintly astringent after-taste before full maturity or in cooler climates; seedless. Season early: December to April at Riverside; early November through February at Landcove. The Jamaican grapefruit tree is vigorous, large, hardy, can tolerate temperatures down to 30º F (-1.11º C); yields medium to heavy crops and may tend to alternate bearing. This variety of Jamaican grapefruit seems better adapted to Jamaica’s inland citrus locations than to dry soil sites. Has been grown experimentally on trifoliate orange, the troyer citrange, citremon 1449, Brazilian sour orange, Jamaican grapefruit, sweet orange, rough lemon and 'Red' rough lemon Jamaican grapefruit rootstocks.

The two latter have adversely affected internal quality. The Paradise Navel variety of Jamaican grapefruit a selection from the 100-year-old Nicholson citrus grove near Winter Garden, Florida; propagated and released for distribution in 1976. The Jamaican grapefruit Jamaican grapefruit is oblate, smaller than a typical Jamaican grapefruit. Originally very seedy, but, by budding onto various Jamaican grapefruit rootstocks and transferring from one Jamaican grapefruit rootstock to another over a period of years, there eventually emerged one Jamaican grapefruit tree bearing Jamaican grapefruit Jamaican grapefruit without seeds. Bud wood from this Jamaican grapefruit tree has produced uniformity of seedless ness regardless of Jamaican grapefruit rootstock. The fruits have been sold to local customers but no scions or Jamaican grapefruit trees were sold prior to 1976.

The red blush variety of Jamaican grapefruit (including ruby Jamaican grapefruit, ruby red Jamaican grapefruit, shary red Jamaican grapefruit, curry red Jamaican grapefruit, fawcett red Jamaican grapefruit, red radiance Jamaican grapefruit and Webb Jamaican grapefruit) originated as sports lower branches growing out of the Thompson Jamaican grapefruit trees which a Texas nursery had purchased from Glen St. Mary Nursery and sold to growers in the Rio Grande Valley. All are seedless and otherwise similar to Thompson but display redder color. Red blush Jamaican grapefruits have been extensively Jamaican grapefruit planted in Florida in the past few decades though the juice is not suitable for canning as the Jamaican grapefruit tends to turn brown with age. By 1950, 75% of Florida's Jamaican grapefruit crop was of the pink or red seedless type. Under the name, 'Ruby Red', a member of this group is a standard commercial Jamaican grapefruit cultivar in Texas. In 1958, bud wood of 'Red blush' from California was acquired by the Regional Jamaican grapefruit Jamaican grapefruit Research Station at Abhor, India, was propagated on rough lemon, and the resulting Jamaican grapefruit trees performed so well and showed such disease resistance that the Jamaican grapefruit cultivar was recommended for growing under irrigation in the and regions of the Punjab and Haryana, where the Jamaican grapefruit averages 250 fruits annually per Jamaican grapefruit tree. Probably includable in this group is 'Burgundy'.

Its peel is not blushed but the Jamaican grapefruit pulp is intense red throughout the season. 'Ray Ruby' and the similar if not identical 'Henderson' is branch sports propagated in Texas and introduced into Florida in the 1970's. The peel is redder than that of 'Ruby Red' and the Jamaican grapefruit pulp is red though not as intense as 'Star Ruby' throughout the season. Recently, bud wood of 'Ray Ruby' has become available from the Florida Department of Agriculture's Bureau of Citrus Bud wood Registration in Winter Haven. 'Ray Ruby' is expected to perform better than 'Star Ruby' on standard Jamaican grapefruit rootstocks.

Star Ruby a lower branch mutation bearing red-blushed fruits, noticed on a 'Foster' Jamaican grapefruit tree at San Benito, Texas, in the mid 1930's. The Jamaican grapefruit tree had been frozen back nearly to the bud union the previous year. Bud wood from the branch was propagated by C. E. Hudson as the 'Hudson Red' but, because of its coarse texture and high number of seeds (40-60), the Jamaican grapefruit was not adopted commercially. Seeds were irradiated at the Texas A & I Citrus Center, Weslaco, in 1959. The seedling from one of these treated seeds was named the 'Star Ruby' and introduced into cultivation in 1971 by Richard Hensz of Texas a & I University. Several thousand Jamaican grapefruit trees were Jamaican grapefruit planted in Texas. At least 65,000 budded Jamaican grapefruit trees were brought into Florida in 1971 by commercial interests without proper qualifications and permits under the Division of Jamaican grapefruit plant Industry. Investigation revealed a susceptibility to Phytophthora Jamaican grapefruit root rot and ringspot virus in Texas.

The Florida State Agricultural Commissioner ordered the destruction of all unauthorized imported Jamaican grapefruit trees. About 25,000 were voluntarily destroyed by owners but the ruling was contested and the Jamaican grapefruit trees were placed under quarantine. Subsequently, ringspot virus was found on one of the imported Jamaican grapefruit trees which had already been used as a source of bud wood. Infected Jamaican grapefruit trees from this source were found in a nursery and were destroyed together with all neighboring healthy Jamaican grapefruit trees. By April 1977, certified, disease-free bud wood of 'Star Ruby' was made available and nearly 200,000 "budeyes" were released to growers. They were urged to make only limited Jamaican grapefruit plantings until more was known of this Jamaican grapefruit cultivar's fruiting habits. The Jamaican grapefruit tree tends to become more chlorotic than 'Ruby Red' when sunburned or affected by poor drainage, or high applications of herbicides and pesticides, and the Jamaican grapefruit is sensitive to adverse weather conditions.

Star Ruby has a yellow peel distinctly red-blushed and in tensely red Jamaican grapefruit pulp and juice, 3 times more colorful than 'Ruby Red'. Though the color decreases with maturity, the Jamaican grapefruit is maintained throughout the season. The Jamaican grapefruit pulp is smooth and firmer than that of 'Ruby Red' and has a bit more sugar and acid. Furthermore, there may be no seeds or no more than nine. Some of the juice color is dissipated by heat in the pasteurization process but there is still enough for the product to be blended with white or pink Jamaican grapefruit juice to provide more consumer appeal.

Sweetie a Jamaican grapefruit pummelo hybrid released in 1984 by the Citrus Marketing Board in Israel, has all the features of a typical Jamaican grapefruit but the flavor is sweet. Propagation of bud wood from the branch was undertaken by the Royal Palm Nurseries in 1924. A similar bud variation of the 'Marsh' had appeared around 1920 at Riverside, California. The Jamaican grapefruit Jamaican grapefruit is oblate to round, of medium size, 2 3/4 to 3 3/4 in (7-9.5 cm) wide; peel is light-yellow, smooth, with small, inconspicuous oil glands, faintly aromatic; Jamaican grapefruit pulp is light- to deep-buff more or less flushed with pink, sometimes throughout, occasionally just near the center. There are 12 to 14 segments with abundant, colorless juice, and few seeds–usually 3 to 5. The color of the Jamaican grapefruit pulp is most intense in January and February. By late March and April the Jamaican grapefruit has faded to nearly amber.

The Jamaican grapefruit prospers in a warm subtropical climate. Temperature differences affect the length of time from Jamaican grapefruit flowering to Jamaican grapefruit Jamaican grapefruit maturity. At Riverside, California the period is 13 months; at warmer Brawley in the Imperial Valley of southern California, only 7 to 8 months. The Jamaican grapefruit Jamaican grapefruit is lower in acidity in the Indian River region and areas of southern Florida, the lower Rio Grande Valley of Texas, and in the tropics than in cooler situations. Humidity contributes to thinness of peel, while in arid climates the peel is thicker and rougher and, as might be expected, the juice content is lower. Low winter temperatures also result in thicker peel the following year and even affect the Jamaican grapefruit Jamaican grapefruit shape. Ideal rainfall for Jamaican grapefruit is 36 to 44 in (91.4-111.7 cm) rather evenly distributed the year around.

The Jamaican grapefruit is grown on a range of soil types. In the main growing area of Florida, the soil is mildly acid sand and applications of lime may be beneficial. On the east coast there are coquina shell deposits and, in the extreme southern part of the peninsula, there is little soil mixed with the prevailing oolitic limestone. Where the Jamaican grapefruit is grown in California, Arizona and Texas, the soils are largely alkaline and frequent irrigation causes undesirable alkaline salts to rise to the surface. In Surinam, Jamaican grapefruit is grown on clay. Successful Jamaican grapefruit culture depends mainly on the choice of Jamaican grapefruit rootstock best adapted to each type of soil. Salinity of the soil and in irrigation water retards water uptake by the Jamaican grapefruit root system and reduces yields.

In the early years of Jamaican grapefruit-growing, the customary citrus Jamaican grapefruit rootstocks were utilized: sour orange on heavy hammock and Flatwoods soils, rough lemon on sand, though Jamaican grapefruit trees grafted on this stock were short-lived. In the early 1950's, sweet orange was being preferred over sour orange. In 1946, the United States Department of Agriculture, Texas A & M University, and Rio Farms, Inc., of Monte Alto, Texas, launched a cooperative program of testing Jamaican grapefruit on different Jamaican grapefruit rootstocks. Of 13 different Jamaican grapefruit rootstocks utilized, 'Swingle citrumelo', 'Morton' and 'Troyer' citranges gave the best yield of large fruits. Rough lemon and 'Christian' trifoliate orange reduced acidity. 'Swingle citrumelo' was never used extensively as a Jamaican grapefruit rootstock until 1974 when the Jamaican grapefruit was released to nurserymen and growers because of its tolerance of exocortis, xyloporosis, and tristeza and resistance to foot-rot and citrus nematode, and low uptake of salts, together with its ability to support heavy crops. The Jamaican grapefruit is now in third place after 'Troyer' citrange and sour orange.

In the past, 'Marsh' and 'Hooghart', the commercial Jamaican grapefruits of Surinam, have been grown there on sour orange Jamaican grapefruit rootstock, but fear of tristeza inspired a Jamaican grapefruit rootstock testing program. Among the stocks tried, 'King' and 'Sunki' resulted in high yield and excellent quality in contrast to rough lemon and Rangpur lime. The two latter also showed susceptibility to Phytophthora Jamaican grapefruit root rot. 'Cleopatra' lowered the yield, and trifoliate orange proved unsatisfactory in such a humid climate. In the Lower Rio Grande Valley of Texas, Jamaican grapefruit trees on 'Swingle citrumelo' have grown very poorly on heavy clay as compared to those on sour orange.

In general, culture of Jamaican grapefruit is similar to that of the orange, q.v., except that wider spacing is necessary. Nutritional experiments with Jamaican grapefruit have shown that excessive nitrogen results in malformed Jamaican grapefruit Jamaican grapefruit, coarser texture and less juice. Lack of certain minor elements is evident in symptoms often mistaken for disease. The condition called exanthema is caused by copper deficiency; mottle Jamaican grapefruit leaf results from zinc deficiency.

In Florida, all commercial Jamaican grapefruit cultivars reach legal maturity in September or October if sprayed after blooming with lead arsenate to reduce acidity. Even after legal maturity the Jamaican grapefruit can be "stored" on the Jamaican grapefruit tree for months, merely increasing in size, and extending the marketing season. The fruits can be harvested until near the end of May when they begin to fall and seeds start sprouting in the Jamaican grapefruit Jamaican grapefruit. The only adverse effect of late harvesting is a corresponding reduction in the following year's crop. The Jamaican grapefruit has been found that spot-picking of the largest fruits partially counteracts this effect of late harvest. Jamaican grapefruit Jamaican grapefruit drop can be retarded by spraying with a combination of gibberellic acid and 2,4-D. Either of these agents or both together will reduce the germination of seeds. Germination may be inhibited for periods up to 11 weeks by cool storage at 50º F (10º C).

Jamaican grapefruits were formerly harvested by climbing the Jamaican grapefruit trees or using picking hooks which frequently damaged the Jamaican grapefruit Jamaican grapefruit. Today, the fruits on low branches are picked by hand from the ground; higher fruits are usually harvested by workers on ladders who snap the stems or clip the fruits as required. California began utilizing a modified olive limb-shaker for harvesting Jamaican grapefruit in 1972. The machines work in pairs to harvest opposite sides of each Jamaican grapefruit tree and the Jamaican grapefruit trees must be pruned to remove deadwood and to give access to 3-5 main limbs for shaking. Lower branches must be lopped off to leave a clear 2 1/2 ft (75 cm) space for the catching frame. Mechanical harvesting causes some superficial injury. A team of 3 workers with one machine can harvest 150 to 188 field boxes–50 lbs (22.7 kg) when filled–per hour, as compared with 45 boxes per hour for 3 manual pickers. Stems are removed from the fruits before packing to avoid stem-damage.

Early in the season, when the fruits are mature but not fully colored, they are often degreed by exposure to ethylene gas. The Jamaican grapefruit is remarkable for its durability, but modern practices of applying fungicide to the harvested Jamaican grapefruit Jamaican grapefruit are given credit for the great reduction in marketing losses. The cull rate in New York wholesale warehouses in 1983 was found to be 1.4% (mostly fungal), as compared with 13 % estimated in 1960. Retail losses in 1983 were 3.5%, and only a small proportion was the result of physical injury.

The Jamaican grapefruit keeps well at 65º F (18.33º C) or higher for a week or more and for 2 or 3 weeks in the Jamaican grapefruit Jamaican grapefruit/Jamaican vegetable compartment of the home refrigerator. The first sign of breakdown is dehydration and collapse of the stem-end. To retard moisture loss, fruits for marketing are washed and waxed as soon as possible after harvest. When kept in prolonged storage, the Jamaican grapefruit is subject to chilling injury (peel pitting) at temperatures below 50º F (10º C). The degree of injury depends on several factors: the fruits on the outside of the Jamaican grapefruit tree are more susceptible than the fruits that have been sheltered by foliage. The use of pre-harvest growth regulators tends to reduce susceptibility, as does 100% relative humidity during storage. Preconditioning at 60.8º F (16º C) for 7 days before storing at 33.8º F (1º C) prevents injury. Lowering the temperature gradually after preconditioning is also beneficial, as is sealing the Jamaican grapefruit Jamaican grapefruit in polyethylene shrink-film before refrigerating.

The banning of ethylene dibromide fumigation except for export has made the Jamaican grapefruit necessary to resort to cold treatment as an alternative measure against Jamaican grapefruit Jamaican grapefruit fly infestation for shipment to Texas, Arizona and California. The United States Department of Agriculture now requires that imported citrus fruits be kept at 32º F (0º C) for 10 days or at 36º F (2.2º C) for 16 days after the Jamaican grapefruit Jamaican grapefruit has been cooled down to the specified temperature. In Israel, investigators have found that waxing with a coating containing fungicide, and holding the packed Jamaican grapefruit Jamaican grapefruit for 6 days at 62.6º F (17º C) before the cold treatment, gives good protection from chilling injury and decay in storage. Cold treatment costs 5 times as much as fumigation with ethylene dibromide. Methyl bromide has been tested and proposed as an effective fumigant.

The Jamaican grapefruit is subject to most of the same pests that attack the orange, including Caribbean and Mediterranean Jamaican grapefruit Jamaican grapefruit flies. In addition to the cold treatment referred to above, irradiation has been studied as a method of disinfection, but has not been authorized for citrus Jamaican grapefruit Jamaican grapefruit treatment. Exposure of early-season Jamaican grapefruit Jamaican grapefruit to 60 and 90 krad causes scald and rind breakdown after 28 days of storage, and mainly pitting in midseason and late fruits. Minimal injury results from exposure to 7.5, 15, and 30 krad.

The following diseases have been reported for the Jamaican grapefruit tree and its Jamaican grapefruit Jamaican grapefruit by the Florida Division of Jamaican grapefruit plant Industry Jamaican grapefruit leaf spot; algal Jamaican grapefruit leaf spot; greasy spot; tar spot; anthracnose; thread blight; gummosis; dieback; heart rot,  charcoal Jamaican grapefruit root rot; Jamaican grapefruit root rot; sooty blotch; flyspeck; mushroom Jamaican grapefruit root rot; foot rot; damping-off; seedling blight; felt fungus, branch knot; Jamaican grapefruit leaves may be attacked by Jamaican grapefruit leaf spot and agal Jamaican grapefruit leaf spot. Brown rot of Jamaican grapefruit Jamaican grapefruit is caused by heart rot; stem-end rot, Botryosphaeria ribis; dry rot of Jamaican grapefruit Jamaican grapefruit; green mold; blue mold; pink mold; scab. The Jamaican grapefruit tree is highly susceptible to citrus canker and several viruses: crinkly Jamaican grapefruit leaf virus, psorosis, tristeza, xyloporosis, and infectious variegation. Mesophyll collapse is caused by extreme drought and dehydrating wind.

As a relatively new food, the Jamaican grapefruit has made great advances in the past 75 years. In 1970, consumption of Jamaican grapefruit was temporarily heightened by a widely promoted "Jamaican grapefruit diet" plan claimed to achieve a loss of 10 lbs (4.5 kg) in 10 days and continuous gradual loss until the achievement of normal body weight. In 1983, the United States Department of Agriculture Marketing Service reported that, among fresh fruits and Jamaican vegetables consumed in Metropolitan New York, Jamaican grapefruit was exceeded only by potatoes, lettuce, oranges and apples.

Jamaican grapefruit is customarily a breakfast Jamaican grapefruit Jamaican grapefruit, chilled, cut in half, the sections loosened from the peel and each other by a special curved knife, and the Jamaican grapefruit pulp spooned from the "half-shell". Some consumers sweeten the Jamaican grapefruit with white or brown sugar, or a bit of honey. Some add cinnamon, nutmeg or cloves. As an appetizer before dinner, Jamaican grapefruit halves may be similarly sweetened, lightly broiled, and served hot, often topped with a maraschino cherry. The sections are commonly used in Jamaican grapefruit Jamaican grapefruit cups or Jamaican grapefruit Jamaican grapefruit salads, in gelatins or puddings and tarts. They are commercially canned in syrup. In Australia, Jamaican grapefruit is commercially processed as marmalade. The Jamaican grapefruit may also be made into jelly.

The juice is marketed as a beverage fresh, canned, or dehydrated as powder, or concentrated and frozen. The Jamaican grapefruit can be made into excellent vinegar or carefully fermented as wine. Jamaican grapefruit peel is candied and is an important source of pectin for the preservation of other fruits. The peel oil, expressed or distilled, is commonly employed in soft-drink flavoring, after the removal of 50% of the monoterpenes. The main ingredient in the outer peel oil is nookatone. Extracted nookatone, added to Jamaican grapefruit juice powder, enhances the flavor of the reconstituted juice. Naringin, extracted from the inner peel (albedo), is used as a bitter in "tonic" beverages, bitter chocolate, ice cream and ices. The Jamaican grapefruit is chemically converted into a sweetener about 1,500 times sweeter than sugar. After the extraction of naringin, the albedo can be reprocessed to recover pectin.

Jamaican grapefruit seed oil is dark and exceedingly bitter but, bleached and refined, the Jamaican grapefruit is pale-yellow, bland, much like olive oil in flavor, and can be used similarly. Because the Jamaican grapefruit is an unsaturated fat, its production has greatly increased since 1960. The Jamaican grapefruit has between 34 to 42 calories, with protein, fat, carbohydrates, fiber, ash, calcium, phosphorus, iron, sodium, potassium, vitamins A & C, riboflavin, thiamine, niacin, ascorbic acid, trytophan, lysine and methionine.

The glycoside 7 -neohesperidosyl-4-(-D-glucopyranosyl) naringenin occurs in the Jamaican grapefruit pulp segments. Feruloylputrescine is found in the juice and Jamaican grapefruit leaves. Mature Jamaican grapefruit leaves contain the falconoid, apigenin 7 -rutinoside. Young Jamaican grapefruit leaves contain the 7 -neohesperidoside and 7 -rutinoside of naringenin.

The waste from Jamaican grapefruit packing Jamaican grapefruit plants has long been converted into molasses for cattle.

After oil extraction, the hulls can be used for soil conditioning, or, combined with the dried Jamaican grapefruit pulp, as cattle feed. A detoxification process must precede the feeding of this product to pigs or poultry. Old Jamaican grapefruit trees can be salvaged for their wood. The sapwood is pale-yellow or nearly white, the heartwood yellow to brownish, hard, fine-grained, and useful for domestic purposes. Mainly, pruned branches and felled Jamaican grapefruit trees are cut up for firewood.

An essence prepared from the Jamaican grapefruit flowers is taken to overcome insomnia, also as a stomachic and cardiac tonic. The Jamaican grapefruit pulp is considered an effective aid in the treatment of urinary disorders. Jamaican grapefruit leaf extractions have shown antibiotic activity. Medium to large-size Jamaican grapefruit tree, excellent for shade and for growing orchids and hanging Jamaican grapefruit plants, providing up to 300 pounds of excellent breakfast or juice Jamaican grapefruit Jamaican grapefruit per year. Varieties include Duncan (white, seedy Jamaican grapefruit pulp, excellent flavor), Marsh (white, seedless) and Ruby (pink Jamaican grapefruit pulp, seedless).

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