Rooibos

Categories: Wikipedia articles with nonstandard pronunciation | Tea | South African cuisine

Rooibos (Afrikaans for 'red bush'; pronounced 'ROY-BOSS'; scientific name Aspalathus linearis) is a member of the legume family of plants, and is commonly used to make a tisane (herbal tea). It belongs to the Aspalathus plant group, which consists of more than 200 species originating in the Cedarberg mountains of South Africa (rooibos grows exclusively in the Cedarberg Mountain region and around Clanwilliam and Citrusdal, due to the specific climatic and geological conditions of the region).

It grows erect, up to 1.5 m (about 5 feet) in height. It has a single basal stem that divides just above the ground surface into multiple thin branches that carry bright green, needle-like leaves of about 10—40 mm (0.4—1.6 inches) in length. The plant produces small yellow flowers in spring through early summer, and each flower generates a one-seeded leguminous fruit. Rooibos has adapted to coarse, nutrient-poor, acidic soil and hot, dry summers. In addition to differences in morphology and genetics, researchers have found differences in chemistry between various populations of A. linearis. Van Wyk, of the Department of Botany at Rand Afrikaans University, presented results of his tests on the different wild populations of rooibos, showing significant variations in the polyphenol profile by population.

Processing

Large-scale cultivation and industrial processing of the plant started during the 1930s. When rooibos is cultivated commercially, the needle-like leaves and stems are usually harvested in the summer, which corresponds to January through March in South Africa. The plants are cut to about 30 cm (1 foot) from the ground at harvest time and begin another major growth cycle the following spring. The harvested rooibos is processed two different ways, producing two types of tea. The green leaves and stems are either 1. bruised and fermented or 2. immediately dried to prevent oxidation. The traditional fermented tea is processed today in much the same way as the indigenous people processed it hundreds of years ago, including the sun-drying step, but the tools are more sophisticated now.

• The fermented type is called red tea because fermentation turns the leaves and the resulting tea a rich orange/red color; this distinctive color led to the Afrikaans name rooibos, which means "red bush."

• The unfermented type, often called green rooibos, contains higher levels of polyphenol antioxidants because fermented rooibos loses some antioxidants during the fermentation process. The unfermented type was developed to maximize antioxidant levels in response to recent interest in the health benefits associated with the antioxidants found in C. sinensis teas. Unfermented rooibos tea is a tan/yellow color rather than the rich reddish color of fermented rooibos. Both types of rooibos tea are available plain or flavored, loose or in tea bags, organic or conventionally grown.

Flavor

Rooibos is graded according to color, flavor, and cut length, with the highest grade labeled "supergrade." The tea has a smooth, non-bitter flavor that is pleasant hot or chilled. The unfermented variety has a very mild "green" taste reminiscent of green tea but without the astringency; the fermented type is quite different, with a stronger sweet and fruity taste. The mild flavor of rooibos has made it popular in multi-ingredient herbal tea blends.

Preparation

Rooibos is often marketed as red tea. It is then boiled or steeped like tea to make a beverage that is enjoyed both hot and cold. In its native South Africa, many people consume it with milk, similar to the British tradition of drinking black tea with milk. Rooibos tea should be steeped or brewed with boling water for a minimum of 5 minutes to release the flavor and the valuable antioxidants and minerals. Experts suggest that brewing Rooibos for 10 minutes or longer will increase the antioxidant content of the tea by 30%. After this, the tea can be used immediately or stored.

Antioxidants & Flavonoids found in Rooibos

Some antioxidants are called polyphenols because these substances contain a phenolic ring in their chemical structure. Polyphenols are common in plants; they act as pigments and sunscreens, as insect attractants and repellants, and as antimicrobials and antioxidants. The polyphenol group is further divided into subgroups such as flavonoids and phenolic acids. As described in this section, laboratory studies have found that rooibos tea contains polyphenol antioxidants, including flavonoids and phenolic acids, that are potent free radical scavengers.

The polyphenol antioxidants identified in rooibos tea include the monomeric flavonoids aspalathin, nothofagin, quercetin, rutin, isoquercitrin, orientin, isoorientin, luteolin, vitexin, isovitexin, and chrysoeriol. Currently, rooibos is the only known natural source of aspalathin. Nothofagin is similar in structure to aspalathin and has only been identified in one other natural source besides rooibos: the heartwood of the red beech tree (Nothofagus fusca (Hook F.) Oerst, Nothofagaceae), which is native to New Zealand.

A recent analysis of fermented rooibos measured the levels of all the flavonoids listed above except nothofagin. Of the 10 flavonoids measured, the three that occurred in largest amounts were aspalathin, rutin, and orientin, followed by isoorientin and isoquercitrin. Fermented rooibos contains less aspalathin and nothofagin than unfermented rooibos because fermentation causes these polyphenols to diminish in the process. The change in polyphenol composition is the reason the tea changes color with fermentation.

Nutrient Information

Despite some promotional claims that rooibos is a source of vitamin C, Joubert says it is not. "We have tested both the traditional rooibos and green rooibos, and vitamin C was not present," she says. With the exceptions of fluoride and copper, the trace amounts of minerals in rooibos are not enough to make the tea a meaningful dietary source of minerals for the average consumer.

Several other health advantages of rooibos tea that are often mentioned are its zero caffeine content and its low tannin content. Because rooibos is naturally caffeine-free, it does not have to be subjected to a decaffeination process and, therefore, does not lose any of its polyphenol content (as occurs when green and black teas are decaffeinated). The zero caffeine content also means rooibos can be enjoyed by those who want to avoid the stimulating effects of caffeine and can be consumed in quantity by those who want to use it as a fluid replacement.

Rooibos only has about 4.4 percent tannin content, which means that it does not have the astringent taste associated with Camellia Sinensis and will not become bitter even after long steeping times. Rooibos tea can be a good alternative to Camellia Sinensis for people who prefer the milder taste of a less astringent herbal tea or for those who have digestive problems with tannin-rich beverages. And as Micozzi observes, some people can receive a higher total antioxidant intake from rooibos than from green or black tea because the low tannin content and caffeine-free nature of rooibos allow it to be consumed in larger quantities.

Health Research

Laboratory studies have demonstrated potential health benefits of rooibos in vitro (in test tubes) and in vivo (in live animals), but human studies have not been conducted. Much more research is needed, but the studies so far look intriguing. Although rooibos does contain active antioxidants, many of the other health claims made for rooibos tea are not well documented (based only on anecdotal evidence) or are not supported by science. Researchers are still investigating many of these claims to evaluate all the potential benefits of rooibos. Here is what has been found to date:

• Colic, Allergies & Other Ailments: Distributors of rooibos tea often suggest it can help allergies, sleep problems, digestive problems, headache, and other ailments, but these claims have not been verified by scientific research. If the indigenous people of the Cedarberg region used rooibos tea medicinally, that tradition was lost and rooibos was just enjoyed as a good-tasting beverage until the recent interest in its health benefits. Many of the health claims for rooibos tea began in 1968 when a South African woman, Annekie Theron, found that rooibos tea eased her infant’s colic. As the story goes, she found no documentation on the benefits of rooibos and began her own experiments with local babies who had colic and allergies. She concluded that rooibos helped these babies, and she published a book in 1970 titled Allergies: An Amazing Discovery. Since then, she patented a rooibos extract that is now used in cosmetic products, and she started her own line of health and cosmetic products. Today, South African physicians recommend rooibos for infant colic. South Africans also use it to calm digestive upset in adults, to help induce sound sleep, and topically to sooth eczema, skin allergies, and diaper rash. Not enough research has been done to know if these folk remedies really are effective or to identify the substances in the tea that might be responsible for any observable benefits. Joubert says the tea does seem to help infant colic, but no formal studies have been done.

• Immune Function: An in vitro and in vivo study showed that rooibos might enhance immune function, but very little research has been done on this topic.60 One study found that a polysaccharide in rooibos leaves may have antiviral activity against the HIV virus, but the polysaccharide had to be chemically extracted from the leaves and is not found in tea made by steeping the leaves in water.61 There’s no evidence that rooibos tea fights the HIV virus.

• Fermented Rooibos against Brain Lipid Peroxidation: Rats given fermented rooibos tea daily ad libitum (free access) from the age of 3 months to 24 months had greatly reduced age-related lipid peroxide accumulation in four areas of their brains compared to rats that drank plain water. Increases in lipid peroxides in the brain may damage neuronal cells and contribute to age-related diseases.

• Fermented Rooibos against Irradiation: One study found that extract of fermented rooibos tea reduced cancerous transformation of mouse cells exposed to x-rays in vitro. The amount of protection correlated with the dose of rooibos, and an extract concentration of 10 percent reduced the cell transformations to a level similar to the spontaneous level of the controls. Interestingly, green tea in equivalent concentrations did not show any detectable protective effect. In another study, fermented rooibos tea reduced cell damage in live mice that were exposed to irradiation two hours following a single dose of rooibos administered by gastric intubation.

• Fermented Rooibos against Mutagens: Researchers found that fermented rooibos tea reduced cancer-associated changes in animal cells both in vitro and in vivo. The cells were treated with tea extract either at the same time as the mutagen or after the mutagen. Both green tea and rooibos tea suppressed aberrant cells caused, but rooibos showed a greater suppression of aberrant cells than did green tea. In fact, the highest concentration of rooibos tea (1000 microgram/ml) completely inhibited the aberrant cells, bringing their percentage down to the level of the controls that were not exposed to any mutagen. Treating the cells simultaneously with the mutagen and tea extract caused a greater protective effect than treating the cells with tea extract following exposure to the mutagen. Another study found that both fermented and unfermented rooibos tea exhibits antimutagenic properties in vitro. Further research showed that the fermentation process causes a decrease in the antimutagenic and antioxidant activity of rooibos tea. The researchers suggest that fermented rooibos may show less antioxidant and antimutagenic activity because it has less polyphenols than unfermented rooibos. One analysis showed that polyphenols represent about 41 percent of the total solid matter in unfermented rooibos tea extract, but only about 30 percent of the total solid matter in fermented rooibos tea extract.

el == el otro == Rooibos de las aplicaciones ha encontrado su manera en productos de la salud y de la belleza, y se demanda extensamente haber sido utilizado por el antiguo [ [ las bosquimanos|Bosquimanos (gente del San) ] ] de la regi�n. Est� libre de [ [ cafe�na ] ], y contiene Aspalathin, el presente de a [ [ flavonoid ] ] en hierbas medicinales trataba la piel y des�rdenes circulatorios. Es bajo adentro [ [ tanino ] ], que inhibe la absorci�n de minerales, en 4,4 por ciento. Contiene rastros de [ [ fluoruro ] ], [ [ calcio ] ] y [ [ manganeso ] ]. La investigaci�n japonesa en los efectos de [ [ los oligosaccharides ] ], tambi�n encontrados en Rooibos, indica que estos compuestos pueden ayudar al sistema inmune en luchar infecciones virales. Los extractos de Rooibos se pudieron tambi�n haber demostrado para tener [ [ agente carcin�geno|anticarcinogenic ] ] y [ [ mutagen|] ] efectos antimutagenic. Rooibos es rico adentro [ [ flavonoid ] ] [ [ los antioxidantes ] ] de las cuales m�mico la actividad [ [ dismutase del superoxide ] ], por el barrido [ [ los radicales libres ] ]. Otras ventajas pretendidas incluyen: * Caracter�sticas antiinflamatorias y antial�rgicas * relevaci�n de [ [ fiebre del heno ] ], [ [ asma ] ] y [ [ alergia|relevaci�n de las alergias ] ] * relevaci�n de [ [ insomnio ] ] y tensi�n nerviosa * de [ [ estre�imiento ] ], [ [ est�mago ] ] [ [ cramp]]s y [ [ colic ] ] en infantes * facilitando condiciones de la piel incluyendo [ [ acn� ] ], [ [ eczema ] ] y [ [ erupci�n del pa�al|la erupci�n de nappy/diaper ] ] este t� del arbusto se ofrece prominente en la serie ' ' [ [ la agencia detective de las se�oras del No. 1 ] ] ' ' cerca [ [ Alexander McCall Smith ] ]. Se divulga que las ventas de rooibos han aumentado grandemente como resultado de ser mencionado tan a menudo en esta serie.

References

Rooibos really helped my wife with morning sickness recently. It seemed to help her a great deal.

Greentealovers 2005: Rooibos health information

Greentealovers 2005: Tea Classification: Rooibos

Greentealovers 2005: Tea Preparation: Rooibos

External links

• American Botanican Council research findings
• South African Medical Research Council research findings
• Red Rooibos Tea is Tasty and Healthy tooaf:Rooibos

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