The processing methods for different tea leaves determine the variations in their aroma. For example: Pu-erh tea, Moonlight White, and Classical Beauty tea produced from the same tea garden in Jingmai exhibit significant differences in aroma.

Variations in processing methods (temperature, heating duration, withering time, drying method, drying temperature) also affect the aroma. For instance: fixation (kill-green) (temperature, duration)—whether the temperature is too high, insufficient, or normal—results in noticeable differences in aroma. Over-fixation (yields a bean-like aroma similar to green tea), insufficient fixation (results in a grassy smell), and proper fixation (produces a fresh fragrance/new tea aroma). This is because during insufficient fixation, an excess of cis-3-hexenol (which has a strong grassy odor) is retained. However, cis-3-hexenol can react under the action of enzymes or heat to form n-hexanol, or undergo isomerization under enzymatic and thermal influence to produce trans-3-hexenol (fresh fragrance/new tea aroma).

II. The Aroma of Pu-erh Tea Depends on Its Precursor Substances

Precursor substances for aroma mainly refer to terpenes, aromatic hydrocarbons and their oxides, carotenoids, amino acids, sugars, etc., present in the fresh tea leaves, as well as certain enzymes involved in aroma formation during processing. The variety and quantity of these substances form the material basis influencing tea aroma. Factors affecting these substances primarily include the tea plant cultivar, regional differences, temperature and humidity, light intensity, light quality, seasonal changes, growing environment, soil conditions, and the tenderness of the fresh leaves, among others. Examples include the Assamica variety versus the Sinensis variety, the Nannuo tea area versus the Bulang tea area, Pasha versus Ban Zhang, normal bud leaves versus purple buds (green bud leaves generally have higher volatile oil content than purple bud leaves).

III. The Influence of Different Storage Conditions on the Aroma of Pu-erh Tea

Tea leaves have a strong tendency to absorb moisture and odors. Temperature, humidity, and foreign odors greatly impact the tea's aroma. Organic substances within the tea leaves, such as polyphenols, amino acids, lipids, and aromatic compounds, are highly susceptible to oxidation in the presence of oxygen. Different storage conditions will determine the direction of change for these aromatic substances. For example: high temperature and high humidity, low temperature and low humidity, high temperature and low humidity, and low temperature and high humidity have significantly different effects on tea aroma (under high temperature and aerobic conditions, lipids can hydrolyze, generating excessive free fatty acids); ventilation versus airtight storage will also yield different results for tea aroma.

Based on experience, an air relative humidity exceeding 75% is quite risky for tea transformation (aging), while lower humidity slows the transformation but preserves the aroma well.

IV. The Influence of Different Brewing Methods on the Aroma of Pu-erh Tea

Taking new raw Pu-erh tea (sheng pu-erh) as an example: the intensity of aroma is directly proportional to water temperature, and high-pouring (pouring water from a height) helps accentuate the aroma.

A good aroma can bring a sense of pleasure. The taste and aroma of the tea soup are the lifeblood of tea. From the tea's aroma, we can also perceive the various differences arising from the fresh leaves, processing methods, and storage conditions.