The fact is that both black tea and green tea come from the same plant: Camellia Sinensis. However, despite their common parentage, both the types of teas are markedly different from one another – in the way they are made, their chemical composition and also their taste.
All about green tea
Green tea is called so because it closely resembles fresh tea leaves – still prime, full of green attributes, and a leafy taste. It is made by applying heat to freshly plucked leaves (a process which is also referred to as fixing), rolled and dried immediately after. In the making of a green tea, the leaves are not allowed to ferment/oxidise which is why the final tea retains much of its green appearance and leafy, vegetal taste.
The chemical composition of green tea is quite complex. Polyphenols constitute much of the leaf components, the main phenolic compounds being epigallocatechin-3-gallate (EGCG), epigallocatechin (EGC), epicatechin-3-gallate(ECG) and epicatechin (EC). Green tea also contains gallic acid (GA), amino acids, proteins, carbohydrates and minerals such as Calcium, Magnesium and Zinc.
All about black tea
Black tea is called so because the final leaves typically have a brownish-black appearance and produce a rich, reddish-brown liquor when steeped. Making this type of tea involves extended periods of leaf withering and complete oxidation/fermentation of the leaves in a temperature and humidity-controlled room. The resultant tea is dark-looking and has a rich woody, nutty, and often tannic taste.
Black tea differs in composition from a fresh leaf in that most of the phenolic compounds in the leaves are converted to their oxidised forms known as theaflavins and thearubigins. Typically, no more than 5-10% of the flavanols survive the processing techniques of a black tea. Changes in leaf pigmentation and aroma also occur due to oxidation. Other than these, black tea retains much of the other chemicals that comprise the fresh leaf.
Differences between black tea and green tea
As a result of their different processing techniques, black tea and green tea are significantly different in their chemical composition and, therefore, their tastes.
First, the main bioactive compounds are different in black tea (theaflavins/thearubigins) and green tea (flavan-3-ol). Due to the lack of oxidation, green tea retains a lot of the flavanols that are otherwise destroyed or transformed during the making of a black tea. The levels of epigallocatechin-3-gallate (EGCG) and total catechins are significantly higher in green tea than black tea.
It is also important to note that the total antioxidant capacity of green tea is significantly more potent than black tea, due to the abundant availability of EGCG compound in the leaves. EGCG is a powerful antioxidant and is widely studied for its ability to trap free radicals and protect against oxidative damage to human cells. EGCG is scarcely present in black tea and no more than 1/5th of the content of the fresh tea leaf. Most of the phenolic compounds are oxidised into theaflavins and thearubigins.
Black tea is richer in gallic acid (GA) – a bitter-tasting, antimutagenic, anticarcinogenic and anti-inflammatory agent – because the amount of it increases during the oxidation process.
Impact of oxidative processing on fresh tea leaf
|Green tea (Non-oxidised )||Black tea (Oxidised)|
|EGCG 184mg||EGCG 22mg|
|EGC 40mg||EGC 19mg|
|EC 20mg||EC 5mg|
|Flavanol derivatives 9mg||Flavanol derivatives 8mg|
|Theaflavins 0.2mg||Theaflavins 14.4mg|
|Thearubigins 2.6mg||Thearubigins 192.7mg|
Source: da Silva Pinto, M., Tea: A new perspective on health benefits, Food Research International (2013), http://dx.doi.org/10.1016/j.foodres.2013.01.038
Potential health benefits: Is one better than the other?
As far as their health benefits are concerned, no gold standard answers yet exist. It is widely held that consumption of both green tea and black tea can impact health positively when combined with a healthy and active lifestyle. But due to the lack of well-controlled, long term human studies, it is difficult and inaccurate to establish if one is healthier or more beneficial than the other.
However, choosing a garden-fresh, good quality tea, cultivated and processed in safe and hygienic conditions is generally considered healthy for consumption. In keeping with this view, Halmari tea gardens and their processing centres have been certified safe and quality conscious. Choose their Green Tea or Black Tea to really drive health benefits.