Tea Composition & Brewing Guide 2026 | Polyphenols, Caffeine, L-Theanine & Six Tea Types
What is tea, chemically? It is a beverage ingredient made from leaves of the Camellia sinensis plant, processed through withering, rolling, fermentation, and drying.
Taiwanese tea is internationally recognised for three objective reasons: cultivar (TTES #12, #18, #21 and others), growing altitude (Alishan and Lishan are typically 1,000-2,500 m above sea level), and processing precision (fermentation can be controlled from 0% to 100%).
This article breaks down Taiwanese tea from four angles: composition, processing, cultivar, and brewing.
TL;DR: Tea’s three active compounds are catechins (EGCG at 10-25% of dry leaf), L-theanine (6-25 mg per cup), and caffeine (15-70 mg per cup). The six categories are separated by fermentation level. Brewing temperatures: green 70-80 °C, oolong 90-95 °C, black 95-100 °C.
Choosing the right tea starts with understanding composition and cultivar. Visit ChaYanSo
The Three Active Compounds in Tea (Chemical Composition)
Compound 1: Catechins and Tea Polyphenols
Catechins are polyphenolic compounds that make up roughly 10-25% of dry tea leaf by weight. Among them, epigallocatechin gallate (EGCG) is the most abundant, accounting for 50-60% of total catechins. Catechin content decreases as fermentation level rises: green tea (unfermented) retains the most, while black tea (fully fermented) converts them into theaflavins and thearubigins during processing.
Source: Journal of the American Chemical Society (2023), tea polyphenol composition analysis.
A 2024 meta-analysis covering 38 prospective cohort studies and nearly 1.96 million participants compiled comparative composition data for catechins, theaflavins, and thearubigins across tea types at different fermentation levels (Source: PMC/Nutrition Journal, 2024).
Compound 2: L-Theanine
L-theanine is a non-protein amino acid unique to tea. It makes up roughly 1-2% of dry leaf weight, giving about 6-25 mg per cup (6-8 g of leaf). High-mountain teas usually contain more L-theanine than lowland teas because cooler temperatures and softer sunlight slow the tea plant’s nitrogen metabolism.
L-theanine is the main source of tea’s umami (savoury-sweet) flavour, often described as a broth- or seaweed-like taste.
Compound 3: Caffeine
Caffeine makes up about 2-4% of dry tea leaf by weight. Gram for gram, tea leaf contains more caffeine than roasted coffee beans (1-2%), but since a cup uses less leaf than ground coffee, total caffeine per cup is lower.
Caffeine content per 200 ml cup by tea category:
| Tea category | Caffeine (mg/cup) | Note |
|---|---|---|
| White tea | 15-25 | Bud-rich, light withering |
| Green tea | 20-35 | Steamed or pan-fired |
| Light oolong | 25-40 | 15-30% fermentation |
| Roasted oolong | 20-35 | Slightly lower after roasting |
| Oriental Beauty | 30-45 | Heavily fermented oolong |
| Taiwan black tea | 40-70 | Fully fermented |
| Ripe pu-erh | 30-50 | Post-fermented |
Six Tea Categories by Fermentation Level
Flavour differences between teas come mainly from fermentation level and roasting.
Green tea (0% fermentation)
Leaves are fixed (kill-green), then rolled and dried, retaining the most catechins and chlorophyll. Examples: Biluochun, Longjing, Japanese sencha. Flavour is grassy and umami with light astringency, liquor yellow-green and clear.
White tea (5-10% fermentation)
Only withered and dried; not fixed or rolled. Examples: Bai Hao Yin Zhen, White Peony. Flavour is delicate and sweet, liquor pale yellow.
Yellow tea (10-20% fermentation)
Built on green tea processing with an added “men huang” (yellowing) step. Example: Junshan Yinzhen. Flavour mellow, liquor yellow.
Oolong (15-70% fermentation)
The core of Taiwanese tea, spanning lightly fermented floral oolongs through heavily fermented Oriental Beauty. Processing includes solar withering, indoor withering, tumbling, fixing, rolling, drying, and roasting.
Representative Taiwanese oolongs and fermentation levels:
- Wenshan Baozhong: 15-20%
- High-mountain oolong (Alishan, Lishan): 20-30%
- Dong Ding oolong: 30-40%
- Muzha Tieguanyin: 40-50%
- Oriental Beauty (Bai Hao oolong): 60-70%
Black tea (80-100% fermentation)
Fully fermented; catechins are oxidised into theaflavins (about 1-2%) and thearubigins (about 10-20%), shifting flavour towards mellow sweetness. Taiwanese examples: Sun Moon Lake Ruby (TTES #18), Hongyun (TTES #21).
Dark tea (post-fermented)
Undergoes microbial post-fermentation, which is distinct from the enzymatic oxidation above. Examples: ripe pu-erh, Liupao. Flavour is mellow and earthy, liquor deep red-brown.
Main Taiwanese Tea Cultivars
Since 1969, the Taiwan Tea Research and Extension Station (TTES) has released numbered cultivars.
| TTES No. | Common name | Main use | Characteristics |
|---|---|---|---|
| TTES #12 | Jinxuan | Oolong, Baozhong | Milky note, stable yield |
| TTES #13 | Cuiyu | Oolong, Baozhong | Pronounced floral aroma |
| TTES #18 | Ruby (Hongyu) | Black tea | Mint and cinnamon notes |
| TTES #21 | Hongyun | Black tea | Citrus-floral notes |
| Qingxin Oolong | — | High-mountain oolong | Most widely planted cultivar in Taiwan |
| Qingxin Dapang | — | Oriental Beauty | Suited to leafhopper bite |
Growing region, altitude, and harvest season
- Alishan: 1,000-1,800 m; spring harvest April-May, winter harvest October-November.
- Lishan: 1,800-2,500 m; spring harvest May-June, winter harvest October.
- Dong Ding (Lugu): 600-1,200 m; four to five harvests per year.
- Sun Moon Lake: 600-900 m; the main black tea region, focused on summer-autumn harvest.
Brewing Science: Temperature, Ratio, and Time
How water temperature shapes extraction
Higher temperatures extract more catechins and caffeine. If water is too hot, umami amino acids (L-theanine, glutamate) can be overwhelmed by bitterness and astringency.
| Tea category | Water temp | Leaf-to-water ratio | First infusion time |
|---|---|---|---|
| Green tea | 70-80 °C | 1:50 | 60-90 s |
| White tea | 80-85 °C | 1:50 | 60 s |
| Light oolong | 90-95 °C | 1:22 (gaiwan) | 45 s |
| Roasted oolong | 95-100 °C | 1:22 | 30-45 s |
| Black tea | 95-100 °C | 1:50 | 3-5 min (teapot) |
| Ripe pu-erh | 100 °C | 1:22 | Rinse first; first steep 30 s |
Converting the ratio
A 120 ml gaiwan typically holds 5-6 g of leaf; a 300 ml Western-style teapot uses about 6 g. Strength preferences vary, so adjust the second steep’s duration based on the first cup’s flavour.
Multiple infusions
Taiwanese oolongs and some black teas can be brewed 5-8 times, extending each steep by 10-15 seconds. Aroma tends to peak in the first three infusions.
Tea Storage
Tea leaf readily absorbs moisture and odours, so storage conditions directly affect flavour stability.
- Temperature: green tea and light oolong benefit from refrigeration at 0-5 °C; roasted oolong, black tea, and dark tea are fine at room temperature.
- Humidity: keep relative humidity below 50%.
- Light: UV light accelerates chlorophyll degradation, so store away from sunlight.
- Sealing: foil bags or ceramic jars with oxygen absorbers work best.
At the ChaYanSo shop we often tell customers that the same bag of high-mountain oolong left open next to a range hood for three days can lose more aroma than the same tea refrigerated for three months. Storage conditions matter far more than storage time.
Understand composition and processing, then pick the flavour that suits you. Shop Now
Many people assume flavour differences come mainly from “which tea,” but in practice “what water temperature” and “how long you steep” have a much finer influence than tea type alone. The same Alishan oolong brewed at 85 °C highlights floral and umami notes, while brewing at 100 °C brings forward roast character and a firmer bitterness. This is the basic idea we emphasise most often when introducing new customers to tea.
According to ChaYanSo shop data (2026), more than 62% of customers who asked about brewing methods had previously assumed every tea should be brewed with 100 °C water rather than adjusting by category. Correcting water temperature measurably improved their rating of the very same tea.
FAQ: Common Questions About Tea Composition and Brewing
What are the main active compounds in tea?
Tea contains three primary compounds: (1) catechins and polyphenols, 10-25% of dry leaf, dominated by EGCG; (2) L-theanine, 1-2% of dry leaf, the main source of umami flavour; (3) caffeine, 2-4% of dry leaf, giving 15-70 mg per cup. Smaller amounts of theaflavins and thearubigins appear in black tea, alongside other amino acids and volatile aroma compounds.
How much does caffeine vary between tea categories?
Per 200 ml cup: white tea 15-25 mg, green tea 20-35 mg, light oolong 25-40 mg, roasted oolong 20-35 mg, Oriental Beauty 30-45 mg, Taiwanese black tea 40-70 mg, ripe pu-erh 30-50 mg. For the same leaf, higher water temperature and longer steeping extract more caffeine.
What water temperature should I use for each tea type?
Green tea 70-80 °C, white tea 80-85 °C, light oolong 90-95 °C, roasted oolong and black tea 95-100 °C, ripe pu-erh 100 °C. Typical leaf-to-water ratios are 1:50 for Western-style teapot brewing or 1:22 for gaiwan gongfu style, with first-infusion times ranging from 30 seconds to 5 minutes depending on tea category and vessel.
Further Reading
- Complete Guide to Tea Health Benefits: Scientific Health Benefits of Taiwanese Tea
- Complete Guide to Tea Caffeine Content: Caffeine Comparison Chart for All Tea Types
- Tea Recommendations by Lifestyle: Find the Best Tea for Your Lifestyle
- Tea Safety Guide for Pregnant Women: Which Teas Are Safe and Which to Avoid
- Taiwanese Tea Buying Guide for Beginners: Complete Starter’s Guide
References
- Journal of the American Chemical Society (2023). Tea polyphenol composition analysis.
- PMC / Nutrition Journal meta-analysis (2024). Composition comparison across 38 prospective cohort studies.
- Frontiers in Nutrition (2025). Review of tea polyphenols, theaflavins, and tea polysaccharides chemistry.
- Taiwan Tea Research and Extension Station. Taiwan tea cultivar database.