These compounds help tea plant fight off pests and diseases. especially useful for the younger leaves and shoots. Among the polyphenols are flavonoids which are broken down during oxidization and then join with to other molecules to create theaflavins and thearubigins, which are responsible for the darker color and stronger flavors that develop during oxidization. Other flavonids such as catechins are important as they are thought to be responsible for not only taste and color but also antioxidants.
Enzymes are important in tea processing especially the oxidization process as this is a reaction of enzymes that causes both the color and the flavor of leaves to change. This reaction can be halted by applying heat which is why -in case of green tea- tea leaves are heated before oxidization occurs to preserve the original color and flavors.
Theanine is the most important amino acid in tea leaf. Amino acids turn turn into polyphenols when plant is exposed to light. It is Theanine compounds which are said to have a positive effect on your mind when absorbed into body alongside caffeine molecules: an effect described as a relaxed uplift but with no crash later, as can happen when you absorb caffeine from coffee.
Catechins are converted into thearubigins as a result of oxidization. they are also known as tannins and usually make the tea darker and more astringent. the higher the oxidization the higher the amount of thearubigins/tannins generated and the darker and more astringent the teas becomes.
Tea plant stores energy as carbohydrates to use it for important reactions in tea leaves.
Selenium, aluminum, fluorine, potassium, zinc, magnesium and iodine are present in tea leaves. Fluorine helps maintaining healthy teeth.
There are different volatile flavor and aroma compounds in tea leaves that when combined make a unique and complex structures that contributes to the taste and aromas in the brewed tea.
Caffeine is the natural stimulant created by tea leaves to form a protection against bugs and pests. Caffeine can affect your heart rate, brain waves and physical function both positively and negatively. Caffeine levels in tea leaves can vary depending on climate and terrain and also the types of leaves being processed. Compare caffeine contents in tea and coffee here: caffeine content of tea and coffee