Tea contains a complex blend of chemical compounds that contribute to its taste, aroma, health benefits, and even colour. Honestly, I still get some of these mixed up - so let's do a recap together.
What Are Tea Polyphenols?
Basically, polyphenols are a diverse group of naturally occurring organic compounds found in plants, and are particularly abundant in tea. These compounds are known for their antioxidant properties, which means they can neutralise harmful free radicals in the body and thereby reduce oxidative stress. Some examples of polyphenols are catechins, theaflavins, and thearubigins.
Catechins
Catechins are a type of flavonoid (which is a type of polyphenolic compound) found in high concentrations in green tea. They are powerful antioxidants and have been extensively studied for their health benefits. Epigallocatechin gallate (EGCG) is one of the most studied catechins due to its potential to fight disease.
Theaflavins
Theaflavins are a type of polyphenol found in black tea. They are formed during the fermentation process of tea leaves and contribute to the tea's characteristic colour and flavour. Theaflavins are known for their antioxidant properties, which can also help protect cells from damage by free radicals.
Thearubigins
Thearubigins are another group of polyphenolic compounds produced during the fermentation of tea leaves, contributing to the dark colour and rich flavour of black tea. They are less studied than theaflavins but are also believed to have antioxidant properties and potential health benefits.
L-Theanine
L-Theanine is an amino acid found uniquely in tea plants (the Camellia Sinensis plant) and some mushrooms. It is particularly noted for its ability to promote relaxation without sedation, making it of interest for reducing stress and improving focus and cognitive performance. L-Theanine is also believed to influence the levels of certain neurotransmitters in the brain, such as serotonin and dopamine, which can positively affect mood and sleep patterns.
Tannins
Tannins are a broad class of compounds found in many plants, including tea. In tea, they contribute to the bitter taste and astringency. Tannins have antioxidant properties and can bind to proteins and other organic compounds, which may contribute to digestive health and reduce nutrient absorption. They are also thought to have antimicrobial effects.
Other Compounds in Tea
Caffeine: A well-known stimulant found in tea that can enhance alertness and concentration. The amount of caffeine in tea can vary widely depending on the type of tea and how it is prepared.
Minerals and Vitamins: Tea leaves contain various minerals (like fluoride, zinc, magnesium, and potassium) and vitamins (including vitamin C, B vitamins, and vitamin K).
Amino Acids: Besides L-Theanine, tea contains several other amino acids that contribute to its flavour profile and possibly its health effects. These include:
Theogallin: Present predominantly in green tea, theogallin possesses antioxidant properties and contributes to the tea's bitter taste profile.
Theanine: A close relative of L-theanine, theanine is found in lower concentrations in tea but still contributes to its savoury taste and purported relaxation effects.
Aspartic Acid: An amino acid found in both green and black teas, aspartic acid contributes to the overall umami taste of tea and plays a role in protein synthesis.
Glutamic Acid: Another savoury amino acid, glutamic acid enhances the flavour profile of tea and is involved in various metabolic processes in the body.
Arginine: Found in small quantities in tea leaves, arginine is an essential amino acid with implications for cardiovascular health and immune function.
Glycine: Known for its calming properties, glycine is found in trace amounts in tea and contributes to its overall taste and potential relaxation effects.
The meagre tea leaf is surprisingly complex, and this post only just scratches the surface. After writing all of this, I'm honestly sweating. I didn't get a B+ in chemistry for nothing.