Almost every night, after I go home and before retiring to bed, I do one thing without fail. I make a cup of green tea (or rarely, black ‘plain tea’ without sugar) and sip it while watching CNN to catch up on the day’s headlines. The tea de-stresses me and puts me in the mood for a good night’s sleep. The feeling one gets when sipping a well-made hot cup of tea is simply indescribable. Needless to say, I also cannot start the day without a cup of tea, this time with milk. Yes, I do sometimes have coffee, but basically, I am a tea person and will choose tea over coffee any day.
But, what makes tea such a fantastic drink ? We all know that tea has a unique set of flavours that stimulates the mind and rejuvenates the body. The Chinese Emperor who accidentally discovered this wonderful brew thousands of years ago immediately warmed up to its healing and soothing qualities and we have been drinking tea ever since. We in Sri Lanka are indeed fortunate that our estates produce some of the world’s best tea.
But until now, there was no real scientific analysis of how tea achieves this effect. Thankfully, botanists have unlocked the genetic secrets of the plant prized for producing tea. A team in China has decoded the genetic building blocks of the tea plant, Camellia sinensis, whose leaves are used for all types of tea, including black, green, yellow, oolong, white and post-fermented. Each has its own aroma, taste and appearance.
The research gives an insight into the chemicals that give tea its flavour(s). Decoding the genome of the tea plant took more than five years. At three billion DNA base pairs in length, the tea plant genome is more than four times the size of the coffee plant genome and much larger than most sequenced plant species. Moreover, tea was found to have many duplicate genes, which may have helped tea plants adapt to different climates and environmental stresses, as tea grows well on several continents in a wide range of climate conditions. The many varieties of tea produced in Sri Lanka are a testimony to this phenomenon.
Until now, little has been known about the genetics of the plant, despite its huge economic and cultural importance. There are many diverse flavours, but the mystery is what determines or what is the genetic basis of tea flavours, says plant geneticist Lizhi Gao of the Kunming Institute of Botany, China, who led the research. The Camellia grouping, or genus, contains over 100 species, including ornamental garden plants. But, only Camellia Sinensis is grown commercially for making tea.
The researchers found that the leaves of the tea plant contain high levels of chemicals that give tea its distinctive flavour. It includes caffeine, the very same ingredients also found in coffee. Previous studies have suggested that tea owes much of its flavour to a group of antioxidants called flavonoids, molecules that are thought to help plants survive in their environments. One, a bitter-tasting flavonoid called catechin, is particularly associated with tea flavour. Levels of catechin and other flavonoids vary among Camellia species. Gao and his colleagues found that C. sinensis leaves not only contain high levels of catechins, caffeine, and flavonoids, but also have multiple copies of the genes that produce caffeine and flavonoids.
Experts say the findings from this study could have a significant impact not only on those involved in the breeding of tea but also those involved in breeding many plants used medicinally and in cosmetics, as the compounds that occur in tea are often associated with the biological properties of plants used medicinally or in cosmetics. Researchers will also get a map of different tea variations and find answers to how it was domesticated, cultivated, and dispersed to different continents of the world.
The genetic knowledge could lead to ways to improve the quality and price of tea, by selective breeding of tea plants. This is already done by the likes of Sri Lanka’s Tea Research Institute, but the additional genetic knowledge will lead to even better results. Armed with the basis for flavours and the processing quality of tea, breeders can look for genetic markers when trying to produce new varieties. Another important finding is that the biochemical pathways involved in the synthesis of the compounds important in the taste of tea are also present in some of the ancestors of tea and have been conserved for about 6.3 million years. In a sense, tea is as old as time itself.
This study will be of interest to our scientists in the tea sector as Sri Lanka must strive to stay ahead in the race to produce the best tea in the world. Pure Ceylon Tea already has that honour, but our competitors are always on the lookout for improving their offerings. The competition is intense, with tea becoming the primary beverage of choice for people the world over apart from water. Even in the US, where coffee is king, tea has seen a steady rise at the expense of fruit drinks and soft drinks which have taken a beating over health concerns.
On the other hand, tea is known to have several health benefits. Tea is good for the heart and boosts the immune system and helps fight heart disease and lower bad cholesterol. It also reduces the risk of stroke and diabetes. Although not quantifiable, tea is known to raise mental alertness levels and impart a general feeling of calm and happiness.
The popularity of tea soared after the invention of the tea bag just over a century ago. Today, there are many innovative forms of tea and some Sri Lankan tea companies have taken the lead in this sphere. There are literally hundreds of varieties of tea infused with various flavours from ginger to jasmine, tea syrup, iced teas and even tea tablets. Such instant teas address the modern consumers’ fast-paced lifestyle. One can make a cup of tea in much the same time it takes to open a can of soft drinks. In the US and UK, there are specialist magazines on tea that have gained popularity among connoisseurs who travel the world in search of exotic teas. The tradition of ‘high tea’ is now practised in thousands of hotels worldwide.
The declining local tea harvest must be a cause for worry for the Sri Lankan tea fraternity. We are yet to cross the 350 million Kg target per year and our contribution to the global tea output is down to about 6 percent. We must endeavour to find new ways and means of increasing the harvest and the diversity of our teas to avoid the risk of being left behind in the race to make the world’s best tea.