Tea has perennially enjoyed the status of a ‘good’ beverage – a ‘healthy’ beverage – ever since it was first found and consumed. And across cultures and borders, this sentiment, by and large, stands true, including in India and here in Assam.
In fact, we actively seek out information to learn more about the beverage and understand it at a deeper, and at a more scientific level. Because the more we seek out the truths, the better we can educate ourselves about the potential of the leaf. And at its highest level, these learnings help us better connect with our own teas in more meaningful ways.
Considering we belong to a region that’s hailed highly for its black tea, we went out exploring the truths, the myths and the fads about the health benefits of black tea. Here’s everything that we’ve found out so far.
Chemical composition of black tea
Black tea chemistry is complex. What comprises a black tea is largely a factor of the nature and quality of the fresh green leaf and the way in which it’s been processed. Typically, black tea is a highly withered, fully-oxidised class of tea. The dry leaves have a dark, almost blackish appearance, and any presence of pubescent buds is indicated by golden/silver colored dry leaves in the mix.
Black tea differs in composition from fresh tea in that most of the leaf’s flavanols (catechins) are converted into their oxidized forms knows as thearubigins and theaflavins. Thearubigins are highly colored flavanols and comprise about 10-40% of the dry black tea leaf while theaflavins comprise no more than 3% of the dry leaf weight.
hearubigins are responsible for imparting a reddish-brown color to the brew while theaflavins give a yellowish-brown tint to the liquor. These compounds are also responsible for the astringency in the cup.
Apart from these, most black teas are rich in amino acids, chiefly theanine – a compound responsible for a tea’s richness and thick texture. It is also one of the most widely studied compounds for its potential impact on mental health, mood, stress, and cognitive performance. In some in vivo studies, theanine has shown neuroprotective effects on the brain.
Caffeine content in black tea is around 3-5% of the dry leaf weight, in most cases. However, there is little-published information around how much of this is actually extracted in a cup. Most studies hint at about 20-30% extraction efficiency and a typical cup of black tea(100ml) tends to have anywhere between 20-50mg of caffeine.
A green tea, in comparison, renders about 10mg of caffeine per cup and an oolong renders anywhere between 13-40mg per cup of tea
Tannins (or depsides) are bitter-tasting compounds and more easily noticeable in a cup made with fully oxidized black tea. Carbohydrates (or free sugars) are present in small numbers and responsible for making the cup more palatable.
In most Assam varieties, Maltose is the most abundant form of carbohydrate, responsible for the characteristic sweet and creamy ‘malty’ taste that’s come to be associated with high-quality Assam black teas. In addition to these nonvolatile compounds, black tea contains visible amounts of volatile compounds like the aromatic carbonyls, alcohols, esters, fluoride, Sulphur compounds and some hydro carbons, too.
Typical chemical composition of Orthodox & CTC teas made from Assam clones
|Composition||Orthodox tea||CTC tea|
|Water soluble solids %||39.52||41.12|
|Total fiber %||19.35||18.93|
|Chlorophyll a mg/g||1.38||0.48|
|Chlorophyll b mg/g||0.77||0.58|
Health benefits of black tea
The chemical composition of a typical black tea, as complex as it is, suggests that it is significantly capable of aiding prevention and protection against harmful effects of a number of toxins.
For one, theaflavins and thearubigins are powerful antioxidants. And an increasing number of studies show that these polyphenols are capable of positively affecting clogged arteries, thereby lowering the risk of heart attack. These polyphenols also help inhibit the growth of harmful bacteria in the body.
Some studies have also found a positive correlation between drinking black tea and lowered risk of diabetes and Parkinson’s disease. Another suggests that the fluoride in black tea is capable of promoting good oral health and bone health.
However, no controlled epidemiological studies have come forward with definite findings. Nonetheless, the scientific community is largely in agreement that regular consumption of good quality black tea, such as an Orthodox tippy Assam black tea, combined with a healthy lifestyle, will have a positive effect on the human body.