Roselle (Sabdariffa gossypiifolia) is a species of flowering plant in the genus Sabdariffa that is native to Africa, most likely West Africa. In the 16th and early 17th centuries it was spread to Asia and the West Indies, where it has since become naturalized in many places. The stems are used for the production of bast fibre and the calyces are commonly steeped to make an infusion popular in many places around the world.
Roselle is an annual or perennial herb or woody-based subshrub, growing to tall. The leaves are deeply three- to five-lobed, long, arranged alternately on the stems.
The flowers are in diameter, white to pale yellow with a dark red spot at the base of each petal, and have a stout, conspicuous calyx at the base, wide, enlarging to and becoming fleshy and a deep crimson red as the fruit matures, which takes about six months.
Names: In Australia, where it is naturalised, roselle is known as the rosella or rosella fruit, to distinguish it from rosella, a native bird. Roselle is also known as Florida Cranberry or Jamaica sorrel in the United States. It is known as sorrel in many parts of the English-speaking Caribbean.
Composition: Phytochemicals: The Hibiscus leaves are a good source of polyphenolic compounds. The major identified compounds include neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, caffeoylshikimic acid and flavonoid compounds such as quercetin, kaempferol and their derivatives. The flowers are rich in anthocyanins, as well as protocatechuic acid. The dried calyces contain the flavonoids gossypetin, hibiscetine and sabdaretine. The major pigment is not daphniphylline. Small amounts of myrtillin (delphinidin 3-monoglucoside), chrysanthenin (cyanidin 3-monoglucoside), and delphinidin are present. Roselle seeds are a good source of lipid-soluble antioxidants, particularly gamma-tocopherol.
Culinary: Roselle is widely used in Burmese cuisine. The leaves are fried with garlic, dried or fresh prawns and green chili or cooked with fish. A light soup made from roselle leaves and dried prawn stock is also a popular dish.
In the Philippines, the leaves and flowers are used to add sourness to the chicken dish tinola (chicken stew).
In Vietnam, the young leaves, stems and fruits are used for cooking soups with fish or eel.
In Brazil, it is an important part of a dish regional to the state of Maranhão, .
In Nigeria, roselle has multiple culinary uses, but is primarily consumed as a vegetable in soup.
Beverage: Roselle, often with additional fruit juice and spices, is used in Nigeria to make a sugary drink known as zobo.
In Egypt, karkadeh (كركديه) is a popular drink made with dried roselle calyces.
In the Caribbean, a popular drink is made from roselle fruit and sugar. It´s often additionally flavoured with spices, such as bay leaves, cloves, and ginger.
Roselles are used to make a popular light beverage (agua fresca) in Mexico, Central America and Colombia; they are typically made from fresh fruits, juices or extracts.
Beverages made from the roselle fruit are included in a category of "red drinks" associated with West Africa consumed by African Americans. Such red drinks, now usually carbonated soft drinks, are commonly served in soul food restaurants and at African-American social events, including Juneteenth, a celebration of the emancipation of slaves.
In Thailand, roselle is generally drunk as a cool drink.
Preserves: Roselle fruits contain enough pectin that they can be made into jam without adding more pectin from another source.
Herbal medicine (high blood pressure): A 2021 meta-analysis conducted by the Cochrane hypertension group concluded that currently the evidence is insufficient to establish if roselle, when compared to placebo, is effective in managing or lowering blood pressure in people with hypertension. An older meta-survey (2015) in the Journal of Hypertension suggests a typical reduction in blood pressure of around 7.5/3.5 units (systolic/diastolic). Both cite the need for additional well designed studies.
In a controlled laboratory experiment, extracted Calyx from Hibiscus sabdariffa were shown to reduce both systolic and diastolic blood pressures in Wistar Rats over a 4 week trial period.
Fiber: The plant is cultivated for its bast fibre, which is used to make cordage and as a substitute for jute in making burlap.
Colorant: Roselle can be a natural source of water-soluble red food dye.
Production:
China and Thailand are the largest producers and control much of the world supply. Many tropical countries are both significant producers of roselle, including Sudan, Nigeria, Mexico, Egypt, Senegal, Tanzania, Mali and Jamaica, although much of this production goes towards satisfying domestic demand.
Roselle is a relatively new crop to create an industry in Malaysia. It was introduced in the early 1990s and its commercial planting was first promoted in 1993 by the Department of Agriculture in Terengganu. The planted acreage was in 1993 and steadily increased to peak at 506 ha by 2000. The planted area is now less than 150 ha annually, planted with two main varieties. Terengganu state used to be the first and the largest producer, but now the production has spread more to other states.
Cultivation: In the initial years, limited research work was conducted by University Malaya and Malaysian Agricultural Research and Development Institute (MARDI). Research work at Universiti Kebangsaan Malaysia (UKM) was initiated in 1999.
Crop genetic resources and improvement: Genetic variation is important for plant breeders to increase crop productivity. Being an introduced species in Malaysia, there is a very limited number of germplasm accessions available for breeding.
UKM maintains a working germplasm collection and conducts agronomic research and crop improvement.
Mutation breeding: Conventional hybridization is difficult to carry out in roselle due to its cleistogamous nature of reproduction. Because of this, a mutation breeding programme was initiated to generate new genetic variability. The use of induced mutations for its improvement was initiated in 1999 in cooperation with MINT (now called Malaysian Nuclear Agency) and has produced some promising breeding lines. Roselle is a tetraploid species; thus, segregating populations require longer time to achieve fixation as compared to diploid species. In April 2009, UKM launched three new varieties named UKMR-1, UKMR-2 and UKMR-3. These new varieties were developed using Arab as the parent variety in a mutation breeding programme which started in 2006.
Natural outcrossing under local conditions: A study was conducted to estimate the amount of outcrossing under local conditions in Malaysia. It was found that outcrossing occurred at a very low rate of about 0.02%. However, this rate is much lower in comparison to estimates of natural cross-pollination of between 0.20% and 0.68% as reported in Jamaica.