This winter, I’ve been drinking rooibos as a hot beverage to avoid the caffeine of tea or coffee and the sugar of hot chocolate. I've also been wondering what rooibos is, where it came from, and how to pronounce it.
Rooibos is made with the needle-like leaves and thin stems of a shrub in the legume family called Aspalathus linearis that grows only in the Cederberg Mountains of South Africa, in the sandy and well-drained soil of a biodiversity hot spot known as the Fynbos Biome. Winters are rainy and can get below 0C, while summers are hot and dry, reaching over 40C. That doesn’t sound so great to me, but so far, rooibos doesn’t grow anywhere else.
One of rooibos's adaptations to dry spells is a long tap root that can reach 3m. And like most other legumes, such as peas, it has nodules that provide an oxygen-free place for anaerobic bacteria that can "fix" nitrogen from the air into a form living things like itself and other plants can use.
The Khoisan peoples, native to the area used the shrub as an herbal tea and a remedy for various ailments. The Swedish botanist Carl Thunberg, who studied under Linnaeus himself, reported on their use in 1772. The Khoisan peoples shared their traditional knowledge with early Dutch settlers, who renamed it “rooibos” (pronounced ROY-boss, meaning “red bush”) and began drinking it in place of expensive black tea from England.
Western research into its cultivation developed in the 1930s. Scientists identified seven ecotypes, according to tea colour and the flavonoid profile. The most popular commercially grown variety is called “Nortier,” after Dr. Pieter le Fras Nortier, who was a leading researcher during the 1930s. Exports peaked during World War II, when Asian sources of tea were interrupted. Following the lifting of anti-apartheid sanctions in South Africa in the late 1990s, interest in and exports of rooibos has grown. The complex politics around rooibos is explored in a 2017 book by Dr. Sarah Ives, called Steeped in Heritage.
Rooibos has yellow flowers which develop into pods. These pods form seeds and open to release them. Farmers collect seeds by sifting the sand around each plant because the shrubs do not grow from cuttings. Farmers prepare rows of raised beds, raking grooves into which they sow the seeds. In a few days, sprouts appear and after that, they begin producing long, thin leaves.
When the Rain Comes
When the first winter rains come, farmers transplant the sprouts to larger fields. The rains are key to their growth, so they don’t require irrigation. Extended droughts, however, can imperil the plants. Winter rains have decreased, probably from climate change, which threatens the entire industry.
Some smaller farms have begun using a more durable wild variety of rooibos based on local traditional knowledge. This variety has a greater capacity to store water in its enlarged roots which helps it resist heat and drought. It can also recover better from fires started by lightning in the summer, which burn off the above ground parts of the plant.
After 18 months, the farmers harvest for the first time. The branches can grow to 60 cm long and the leaves grow to 60 mm long. Farmers prune the shrubs to about 50 cm above ground with a hand scythe, gathering both the leaves and stems. Hand harvesting is supposed to be better for regrowth and budding. Between January and April, farmers harvest the plants in this way every year for about four to six years. The wild variety grows more slowly than the commercial variety and is only harvested every second year. The plants can be productive for 50 years.
Processing rooibos is now mostly mechanized, but it follows the same steps originally performed by hand. After workers harvest the material, machines beat the plant material to bruise it and chop it into smaller bits.
This material is wet and left outside for enzymatic oxidation to occur. This is often called fermentation but does not involve microbes like the fermentation of alcoholic beverages. It involves an enzyme called polyphenoloxidase which many plants produce as a defence mechanism. It is what makes most apples go brown when they cut and exposed to oxygen. In this case, it changes the flavour and colour of the material to the characteristic reddish brown.
Green rooibos is now available as well, although it's not as common as red. I bought some to try for the sake of this post. The dry material looked greener, but the colour of the beverage was still orange, though not quite as dark as the regular rooibos. I found it to have a lighter taste, a little more like grass, which might not sound appealing but was pleasant.
Green rooibos is processed differently than red rooibos. Leaves from the rooibos plant aren't fermented; they're spread out to dry in the sun. Then the leaves are scooped, cleaned, and pasteurized. Rooibos is graded by colour, aroma, and flavour.
I have been drinking rooibos because of the flavour and because of what it doesn't have, namely caffeine. It is also low in tannins, so it can steep for a long time without making your tongue feel like sandpaper. Many advertisements cite the abundance of antioxidants in rooibos, including quercetin and aspalathin.
Some people choose the green rooibos because it has more antioxidants in it than red rooibos. But antioxidants tend to be overly hyped for their benefits. And, in any case, living things do not seem to absorb aspalathin very well. The nutritional benefits (and potential drawbacks) of rooibos still requires more research, but I'm not staying awake worrying about it.