Mail & Guardian reporter
When you reach into the fridge for a bottle of iced tea, does the sight of cloudy liquid swirling around in a chilled bottle of iced tea make you think that its gone off or do you prefer it to the clear sterility of the different brand next to it.
The world is firmly divided into clear and turbid iced-tea drinkers, and South African scientists are working to supply both sets of demands of the spectrum. Dr Zeno Apostolides of the University of Pretoria heads one team that, with funding from the Technology and Human Resources for Industry Programme (Thrip), is working to improve the international demand for South African tea.
There are 10 tea estates in South Africa, which supply about half of the local demand. Unfortunately, the tea is, Apostolides admits, “mediocre”. In part this is because tea trees like the wet, low-altitude environment. They grow with enthusiasm and a hectare of tea produces up to four tonnes of leaves a year. In comparison the slower growing teas at high altitudes, such as the famed Darjeeling, only produce a quarter as much. But what they lack in quantity such “high grown” teas compensate with quality, having much higher levels of aromatic compounds and flavours.
The ideal for hot tea is an aromatic tea that grows fast, and this is the goal of the tea council’s research programme. Consumer reluctance means that no genetically modified teas are grown commercially, so the old-fashioned method of plant breeding reigns supreme.
Taking three years to start producing, tea trees can grow to the size of a mulberry tree if left unpruned. To facilitate picking, they’re usually pruned to waist height and a metre in diameter. The picking season in Southern Africa is November to April, the hot, wet time of year. Tea plantations are normally replanted at a rate of 3% a year, although trees can continue growing for a century. Some old tea gardens in India and Sri Lanka still produce tea from trees more than 100 years old.
Just like grapes, there are different tea cultivars, although their strictly utilitarian brand names such as PC118 are a far cry from the more romantic wine names such as hanepoot.
South Africa’s mediocre teas are actually ideal for iced-tea making because the flavour of the leaves is largely obscured in manufacturing when flavours and sweeteners are added. Unfortunately, South African tea samples sent to international companies proved too turbid.
Ironically, this is because local tea trees have been developed for a hot tea market, that likes the precipitation that makes cold tea cloudy.
So, backed with Thrip funding and the tea council, Apostolides is working on methods of reducing the cloudiness in the tea by using enzymes. The most promising approach is using an enzyme known as tannase, which is imported from Japan and America. Tannase, which is produced by a fungus, aspergillus nigra, breaks down tannin and clears up the complex of polyphenols and caffeine that produces cloudiness.
Uniquely, however, Apostolides and his team are looking at adding tannase to the tea leaves when they are macerated, before being dried. Elsewhere in the world the enzyme is used in a powder form on the dried leaves.
But tea research is a regional issue; South Africa is a member of the Tea Research Foundation of Central Africa, along with Zimbabwe and Malawi. Research is being done into the genetics of tea plants, methods of growing them and processing the picked leaves. If Apostolides’ research works out, the rest of the world may also be enjoying South African home-brew, albeit in a glass bottle of iced tea rather than a can.