People start their mornings with a cup of tea instead of using an alarm. However, beneath its comfortable warmth is an interesting system of plant biological processes, enzyme activities, interactions between molecules, and physiological responses—concepts that are often studied in depth by students pursuing a BSc Course in biological sciences.
Tea is not only a relaxing drink, but it contains a range of biological plant ingredients which boost digestion, activate the neurological system, and provide the body with healthy radicals.
Plant source of tea
Tea is derived from the Camellia sinensis plant and originated in China before spreading to other major tea-producing regions such as India and Sri Lanka.
All varieties of tea are produced from this same plant but are prepared differently. The differences in processing methods, especially enzymatic oxidation, cause variations in flavour, colour, and bioactive substances.
Chemical Constituents
Tea has almost 2,000 recognized biologically active substances. The key essential components are:
a) Polyphenols (30–40% of dry weight)
Taste properties and beneficial effects are both attributed to polyphenols. Key components found in tea include:
- Catechins
- Theaflavins
- Thearubigins
b) Caffeine:
Each cup of tea includes 20–60 mg of caffeine, which increases alertness and decreases tiredness by blocking adenosine signals.
Brewing Science
To make tea, boiled water is combined with tea leaves. The size of the leaves, temperature of the water, and steeping time determine the flavour.
Brewing Conditions:
- For green tea: 70–80°C for 2–3 minutes
- For black tea: 90–100°C for 3–5 minutes
Physiological Effects of Tea
a) Antioxidant defence
Tea polyphenols help neutralize free radicals and support immune-related biological processes.
b) Cardiovascular Benefits
Daily tea consumption is associated with improved heart health and reduced oxidation of bad cholesterol.
c) Metabolic Regulation
Catechins slightly boost metabolism and help break down fatty acids for energy production.
Aroma
The fermentation and processing of tea leaves produce natural compounds that give tea its fragrance.
Milk and Tea
When milk is added to tea, casein proteins bind with polyphenols, affecting flavour and reducing antioxidant availability.
Tea and Microbial Fermentation
Kombucha tea is produced through microbial fermentation where yeast and bacteria transform tea into a drink containing gases, acids, and beneficial microbes.
This process gives kombucha its slight sour taste and fizzy texture.
Conclusion
Every cup of tea is a complete biochemical system, from catechin oxidation to caffeine’s neurological effects.
When you brew tea, you are initiating a precise chemical process shaped by science and tradition.
Frequently Asked Questions (FAQs)
Q.1. Where do all authentic teas come from botanically?
Ans.: The Camellia sinensis plant is the source of all authentic teas.
Q.2. Why is green tea high in antioxidants?
Ans.: Green tea retains high catechin content due to minimal oxidation, which helps neutralize free radicals.
Author
Dr. Smita Sisodiya
Assistant Professor, Biotechnology
Biyani Girls College, Jaipur