Deep Dive into Tea

A cup of tea's fresh, sweet, or bitter notes come from a diverse mix of chemical compounds in the leaves. Key contributors include polyphenols, amino acids, alkaloids, sugars, proteins, pectins, aromatic compounds, enzymes, organic acids, pigments, vitamins, and inorganic minerals. Fresh tea leaves are about 75–78% water; the remaining 22–25% are dry matter, packed with these bioactive substances.

Tea Polyphenols

Polyphenols make up 20–35% of tea's dry mass and are also known as tannins or tea astringents. These include catechins, flavonoids, anthocyanins, phenolic acids, and condensed tannins. Catechins, comprising 60–80% of total polyphenols, are key to tea’s color, flavor, and fragrance.

Catechins protect pigments and vitamins in food, prevent spoilage, improve storage stability, fight odors, and stabilize cellulose. As natural antioxidants, they scavenge free radicals and support anti-aging, anti-allergy, detox, digestion, radiation protection, dental health, and skincare. They may also help manage conditions like hypertension, thrombosis, asthma, constipation, diarrhea, and scurvy.

During tea processing, polyphenols oxidize—like varying fermentation levels—leading to distinct colors, aromas, and tastes that define the six major tea types. Astringency in tea comes mainly from these polyphenols.

Proteins & Amino Acids

Proteins form 20–30% of tea’s dry matter, but only 1–2% are water-soluble and contribute to taste. Drinking 10 g of tea per day provides just ~0.2 g protein, while adult needs are 70–90 g—so tea isn't a protein source, merely taste enrichers. These proteins are made from 20+ amino acids, with fresh leaves containing 2–5% total amino acids.

Amino acids (1–4% of dry mass) such as theanine, glutamic acid, and aspartic acid define tea's taste and aroma. They balance polyphenol bitterness and caffeine’s harshness, contributing to overall flavor. Theanine is unique to tea—about 70% of amino acids in the leaf—and delivers a refreshing, umami sweetness. It boosts immunity, raises dopamine, and calms nervousness, anxiety, and depression. While caffeine may disrupt sleep initially, theanine helps calm and improve sleep quality over time. Amino acid content is higher in small-leaf and less fermented teas, tender shoots, spring harvests—explaining why spring teas taste especially fresh.

Alkaloids (Caffeine Family)

Alkaloids, 2–5% of dry mass, include caffeine, theobromine, and theophylline. Tea leaves often contain 2–5% caffeine (versus coffee’s 1–2.5%). Caffeine is bitter, water-soluble, and influenced by leaf maturity, sunlight, season, and processing. First brews release ~70% of caffeine—so short infusions reduce intake. Dark teas like black tea and white tea have comparatively lower caffeine.

Sugars & Pectins

Sugars account for 20–25% of dry mass—soluble mono-/disaccharides and insoluble polysaccharides like starch, cellulose, hemicellulose, lignin, and pectin. Soluble sugars contribute to sweetness and mouthfeel. Enzymatic and water-based breakdown during processing increases soluble sugars, enhancing flavor. Free sugars are <1% and tea (without additives) has negligible sugar (~0.1–0.5 g/100 ml), making it virtually zero-calorie. Sweetness arises from the tea itself only when sugar is added.

Pectins (~4% of dry mass) are polysaccharides helping shape tea during rolling and contribute to viscosity and luster. They support digestion, regulate blood sugar, lower cholesterol, and boost immunity.

Organic Acids & Lipids

Organic acids (~3%) include citric, malic, gallic, ascorbic, succinic, and oxalic acids, alongside acidic amino acids—key to aroma and taste balance. Lipids (~8%) such as phospholipids, glycerides, glycolipids, and sulfolipids contribute to aroma retention and cellular regulation. Tea seeds contain ~40% lipids; leaves ~8%. Unsaturated fatty acids predominate. Oil droplets visible in hot tea come from these lipids. Dietary lipids help breakdown and are important sources of essential fatty acids—green tea (~1.1%), oolong (~2.4%), dark (~4–5%) teas. Though small in quantity, tea lipids may have anticancer and immune-enhancing effects.

Pigments

Pigments (~1%) determine leaf and liquor color. Lipid-soluble pigments include chlorophyll, lutein, and carotene; water-soluble ones include flavonoids, anthocyanins, and oxidized polyphenols. These influence appearance and quality.

Aromatic Compounds

Volatile aroma substances range from 0.005–0.03%, depending on type, but are essential to tea’s sensory profile. Over 700 aroma compounds are known—alcohols, aldehydes, ketones, acids, esters, phenols, sulfur compounds, and more. Varieties, processing, and terroir create a complex aroma palette.

Vitamins & Enzymes

Vitamins (~0.6–1%) include water-soluble (B-group, C) and fat-soluble vitamins. Vitamin C has anti-inflammatory, anti-allergy, anti-anemia, and skincare benefits. B1 supports skin health; B2 smooths wrinkles and spots; B6 aids metabolism and complexion—earning its nickname “beauty vitamin.”

Enzymes (proteins) drive processing chemistry—like inactivating with heat (green tea) or activating oxidation (black tea), shaping each tea’s profile.

Inorganic Minerals

Final Takeaway

Tea’s richness comes from its complex chemistry: polyphenols (astringency), amino acids (umami), caffeine (bitterness/stimulus), sugar/pectin (sweetness and body), acids, enzymes, pigments, vitamins, and minerals. Each component and processing step shapes that unique cup experience—sweet, fresh, strong, or soothing. Cheers to the science behind every sip!