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The oroblanco, oro blanco, or sweetie ('' Citrus grandis'' Osbeck × '' C. paradisi'' Macf.) is a
citrus ''Citrus'' is a genus of flowering trees and shrubs in the family Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, mandarins, lemons, grapefruits, pomelos, and limes. ''Citrus'' is nativ ...
hybrid, resulting from a cross between an acidless
pomelo The pomelo ( ; or pummelo, ''Citrus maxima''), also known as a shaddock, is the largest citrus fruit. It is an ancestor of several cultivated citrus species, including the bitter orange and the grapefruit. It is a natural, non-hybrid citrus fr ...
and a Marsh grapefruit. Its
fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...
is
oblate In Christianity (specifically the Roman Catholic, Orthodox, Lutheran, Anglican and Methodist traditions), an oblate is a person associated with a Benedictine monastery or convent who is specifically dedicated to God and service. Oblates are i ...
and mostly
seedless A seedless fruit is a fruit developed to possess no mature seeds. Since eating seedless fruits is generally easier and more convenient, they are considered commercially valuable. Most commercially produced seedless fruits have been developed from ...
, with a thick rind that remains green long after it has already matured. It has a sweet, mild taste, and lacks the bitterness generally associated with grapefruit. It requires less heat to grow than other varieties of grapefruit and are harvestable sooner. Oroblancos grown in moderate climates tend to yield the highest-quality fruit. The hybrid was first created by two geneticists at the
University of California, Riverside The University of California, Riverside (UCR or UC Riverside) is a public university, public Land-grant university, land-grant research university in Riverside, California, United States. It is one of the ten campuses of the University of Cali ...
, James W. Cameron and
Robert Soost Robert K. Soost (November 13, 1920, Sacramento – March 8, 2009) was a citrus expert and professor of genetics at University of California, Riverside, and sixth curator of the University of California Citrus Variety Collection. He studied at U ...
, in April 1958. It was later released to growers in 1980, who rapidly adopted it. It initially struggled in American markets, but had a resurgence in popularity after growers in
Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...
began advertising its sweet taste and green color to consumers in
Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
,
China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
, and
Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...
. It was exported to growers in
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
in 1990, where it was also commercially unsuccessful.


Description


Characteristics

The oroblanco is a
triploid Polyploidy is a condition in which the cells of an organism have more than two paired sets of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two complete sets of chromosomes, one fro ...
citrus ''Citrus'' is a genus of flowering trees and shrubs in the family Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, mandarins, lemons, grapefruits, pomelos, and limes. ''Citrus'' is nativ ...
hybrid, resulting from a cross between an acidless
pomelo The pomelo ( ; or pummelo, ''Citrus maxima''), also known as a shaddock, is the largest citrus fruit. It is an ancestor of several cultivated citrus species, including the bitter orange and the grapefruit. It is a natural, non-hybrid citrus fr ...
(''C. grandis'' Osbeck) and the Marsh grapefruit (''C. paradisi'' Macf.). Its fruit is
seedless A seedless fruit is a fruit developed to possess no mature seeds. Since eating seedless fruits is generally easier and more convenient, they are considered commercially valuable. Most commercially produced seedless fruits have been developed from ...
with pale yellow flesh and is slightly less juicy than other grapefruits, though it does have a juice content of roughly thirty percent. Rarely, it contains small, aborted seeds. It has a thick, smooth peel which is very slow to transition from green to yellow; in fact, the rind only turns yellow weeks after the fruit has already matured. A consequence of its thicker rind is less edible flesh. It has a thick white
pith Pith, or medulla, is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which in some cases can store starch. In eudicotyledons, pith is located in the center of the stem. In monocotyledons, it ex ...
and a large hollow core, and is
oblate In Christianity (specifically the Roman Catholic, Orthodox, Lutheran, Anglican and Methodist traditions), an oblate is a person associated with a Benedictine monastery or convent who is specifically dedicated to God and service. Oblates are i ...
. Once mature, the fruit weigh roughly , and have a diameter of about . A 2020 study found that the fruit retained many of the compounds found in grapefruit including
terpenes Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predomi ...
and polyphenols.


Flavor

The flavor of the oroblanco is mild and sweet. As it descends from an acidless pomelo, it lacks the bitterness generally associated with grapefruit, although it does attain an acidic aftertaste if grown in colder environments, or if eaten earlier in the growing season. Its rind and membrane also possess a bitter taste due to their naringin content. The fruit's
Brix Degrees Brix (symbol °Bx) is a measure of the dissolved solids in a liquid, based on its specific gravity, and is commonly used to measure dissolved sugar content of a solution. One degree Brix is 1 gram of sucrose solute dissolved in 100 grams ...
/
acid An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...
ratio, which contrasts a fruit's levels of sweetness and acidity, is considerably higher than those of other grapefruit varieties; in California, it is required to have a ratio of at least 10:1. By comparison, Marsh grapefruit tested in Australia were found to have a ratio of 4.5:1. Its aroma is "citrusy" and "floral".


Harvest

Prior to its release, researches planted oroblanco trees in a mild climate, a cold and humid climate, and a desert climate to analyze its production in different settings. They found that the specimens produced in the hotter climate were of a lower quality, and that those in the colder climate were excessively acidic. They thus determined that mild, inland climates were optimal for oroblanco growth. The oroblanco needs less heat than a standard grapefruit to sweeten and are harvestable sooner than other grapefruit varieties. Oroblancos have been cultivated in
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
,
Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
,
Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...
, and
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
. In California, their harvest season can last from late November to March. In Australia, where they are grown in the
temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...
,
subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...
, and
tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...
zones, harvest can last anywhere from February to December, depending on the region and how much heat is received. Its yield size may vary; during seasons of heavier yields, the average size of the fruit decreases. The tree of the oroblanco quickly grows tall and spreads outward, requiring an allowance of more than 20 feet horizontally when cultivated, and usually begins to yield fruit within five years of being planted. It is susceptible to
citrus tristeza virus ''Citrus'' is a genus of flowering trees and shrubs in the family Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, mandarins, lemons, grapefruits, pomelos, and limes. ''Citrus'' is native to S ...
; a common symptom of CTV in oroblancos is stem-pitting, which stunts tree growth and leads to fruit of small size and low quality. It is also susceptible to fruit fly infestations.


History

The oroblanco was first created as the result of a cross between an acidless
pomelo The pomelo ( ; or pummelo, ''Citrus maxima''), also known as a shaddock, is the largest citrus fruit. It is an ancestor of several cultivated citrus species, including the bitter orange and the grapefruit. It is a natural, non-hybrid citrus fr ...
(''C. grandis'' Osbeck) and the Marsh grapefruit (''C. paradisi'' Macf.) carried out in April 1958 by
Robert Soost Robert K. Soost (November 13, 1920, Sacramento – March 8, 2009) was a citrus expert and professor of genetics at University of California, Riverside, and sixth curator of the University of California Citrus Variety Collection. He studied at U ...
and James W. Cameron, geneticists at the
University of California, Riverside The University of California, Riverside (UCR or UC Riverside) is a public university, public Land-grant university, land-grant research university in Riverside, California, United States. It is one of the ten campuses of the University of Cali ...
. The cross resulted in seven
cultivars A cultivar is a kind of cultivated plant that people have selected for desired traits and which retains those traits when propagated. Methods used to propagate cultivars include division, root and stem cuttings, offsets, grafting, tissue cult ...
, of which six were triploids and one was a tetraploid. In 1962, these seven cultivars were planted in fields in Riverside; later, trees were also planted at research stations in
Exeter Exeter ( ) is a City status in the United Kingdom, cathedral city and the county town of Devon in South West England. It is situated on the River Exe, approximately northeast of Plymouth and southwest of Bristol. In Roman Britain, Exeter w ...
, Santa Ana, and the
Coachella Valley The Coachella Valley ( ) is an arid rift valley in the Colorado Desert of Southern California in Riverside County. The valley has been referred to as Greater Palm Springs and occasionally the Palm Springs Area due to the historic promine ...
to test its production in differing climates. Of the cultivars planted, one labelled 6C26,20 was selected and designated "oroblanco", meaning "white gold" in
Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many countries in the Americas **Spanish cuisine **Spanish history **Spanish culture ...
. The oroblanco was commercially released to growers in 1980, with the
patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...
belonging to the
Regents of the University of California The Regents of the University of California (also referred to as the Board of Regents to distinguish the board from the corporation it governs of the same name) is the governing board of the University of California (UC), a state university sys ...
. A separate cultivar from Soost and Cameron's cross in 1958 was also released under the name "
melogold The Melogold or Melogold grapefruit ('' Citrus grandis'' Osbeck × '' C. Paradisi'' Macf.) is a citrus hybrid similar to the oroblanco; both result from a cross between the pomelo and the grapefruit and is a fruit similar to a sweet grapefruit ...
" in 1986. Following its release, the oroblanco was rapidly adopted by growers. However, it proved unpopular in American markets due to its thick peel, which is slow to transition from green to yellow, leading consumers to believe it was still unripe. Many of the trees planted were removed or had different grapefruit varieties grafted onto them. It was exported to Australian growers in 1990 and released there the same year, distributed by the Australian Nurserymen’s Fruit Improvement Company. It failed to gain popularity there as well, leading to many of those trees being removed. The oroblanco later saw a resurgence in popularity after growers in
Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...
began growing the fruit. After branding the fruits "Sweeties" and "Golden Sweeties" and advertising their green peels and sweet flavor, Israeli growers found a large market of buyers for the oroblanco in Japan, where it became a success. Exports of the fruit from Israel and
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
to
Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...
also started around the same time. This led to a renewal of the tree's cultivation in the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
, with trees being planted in
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
and
Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
. Israel also found buyers for oroblancos in
China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
; 3,000 tons of the fruit were exported there by Israel in 2018. Regardless, oroblanco yield still trails behind that of the more popular Marsh grapefruit, and despite its resurgence, it continues to decrease in popularity in California, falling from 1,105 acres of oroblancos in 2004 to 233 acres in 2024, a decline of nearly 79 percent.


References


External links

* {{authority control Citrus hybrids Grapefruit