Tea sensory evaluation is the process by which evaluators use their normal senses of sight, smell, taste, and touch to comprehensively analyze and evaluate the quality factors of tea products, including appearance, liquor color, aroma, taste, and leaf residue. It is a quick and effective method for assessing quality differences and analyzing quality problems in tea production.
As the saying goes, "Interest is the best teacher." To truly excel in any field, the best approach is to fall in love with it, and this is especially true when it comes to tea tasting. Tea is rich in caffeine and polyphenols, so bitterness and astringency are inherent characteristics of tea. While aversion to bitterness and astringency is human nature, people accept and even come to love the bitter and astringent taste of tea because of the pleasant sensations it provides: a clean and refreshing feeling in the mouth, a sense of relaxation in the body, and the joy of sharing the experience with fellow tea lovers.
The first step in tea tasting is to be able to distinguish between the inherent flavor of the tea and the bitterness or astringency caused by improper processing or poor tea garden management.
Let's take the tea from Bulang Mountain as an example. Compared to teas from Nanluo Mountain and Jingmai Mountain, Bulang Mountain tea has a more pronounced bitterness from the initial taste to the aftertaste. However, the bitterness of Bulang Mountain tea is accompanied by a certain degree of sweetness, which is a characteristic style of the tea from the Bulang Mountain sub-region and represents the tea's inherent flavor. The tasting term for this is "strong." If the tea also has a corresponding richness or body, it can be recorded as "rich and strong." If the aftertaste is quickly and noticeably sweet, you can add "quickly and noticeably sweet aftertaste" after "rich and strong." In the overall evaluation, you can note "possesses a certain bitter tea style." In the market, most products with a certain bitter tea style have relatively less noticeable astringency, while the aftertaste is stronger, broader, and even deeper. This is the main reason why tea from Bulang Mountain is so popular in the market.
During evaluation, sometimes some sun-dried green teas exhibit a bitter taste accompanied by a raw, grassy flavor. This is caused by insufficient high-temperature steam during the de-enzyming process or by the steaming time being too short, resulting in a raw, bitter taste with a grassy undertone. This is a quality problem caused by inadequate processing techniques. The evaluation record for taste can include "has a raw, grassy flavor" or "slightly has a raw, grassy flavor."
You might also encounter a bitter taste in the tea that has a cooling or damp sensation; this is usually caused by shady and damp tea gardens and insufficient sunlight for the tea plants. When making an overall assessment, you can note "has a damp bitterness" or "the tea is slightly cooling."
Having discussed bitterness, let's talk about the "astringency" of tea. Astringency is an inherent characteristic of tea, resulting from the action of polyphenols on the oral mucosa, causing reversible protein coagulation and producing a wrinkled, rough, and dry sensation in the mouth and throat. In normal tea, the coagulated proteins responsible for astringency can be washed away by secretions from the small glands beneath the oral mucosa. This sensation is perceived as the astringency dissipating, the oral mucosa relaxing, and the lubricating effect of the subcutaneous gland secretions becoming more prominent—what is commonly known as "astringency stimulating saliva production." This is one of the physiological reasons why drinking tea makes people feel relaxed and happy.
Having discussed the inherent flavor of tea, let's talk about the terms "bitter" and "astringent" in tea evaluation terminology. In tea evaluation, a normal bitterness and astringency that dissipates, leaving a slightly sweet aftertaste, is described as "mellow" in tea flavor. If the taste is correct but the tea flavor is slightly weaker, it can be recorded as "pure" in flavor. However, if after swallowing or spitting out the tea, the aftertaste leaves a numbing or heavy sensation in the mouth, it is recorded as "astringent." Similarly, only if the bitterness persists or intensifies after swallowing or spitting out the tea is it recorded as "bitter." Understanding this distinction reveals that the term "bitter" in food flavor is different from the term "bitter" in tea evaluation terminology.
We will take the evaluation of sun-dried green tea, a raw material for Pu-erh tea, as an example. Sun-dried green tea is a type of primary processed tea. According to the "Tea Sensory Evaluation Method," the quality of primary processed tea is evaluated based on five factors: appearance, liquor color, aroma, taste, and leaf residue.
Step 1: Sampling. The internal quality assessment of the tea is based on the tea liquor brewed from the 3 or 5 grams of tea weighed out. Whether this bowl of tea liquor accurately represents the true quality of the entire batch of tea depends on the sampling and brewing process.
Step 2: Preparation for evaluation. The essence of evaluation is measurement and comparison. The principle is that for the evaluation of a batch of tea, the utensils, tea-to-water ratio, water source, and water temperature must be the same. The tea should be steeped simultaneously, the infusion poured simultaneously, and the evaluation and comparison of the samples conducted simultaneously. The evaluation focuses on identifying problems in certain aspects of the samples or assessing the degree of pleasure derived from their aroma and taste. Based on the evaluation results, a quality judgment is made, suggestions for improvement are provided, and guidance is given for production and consumption. Therefore, the core of evaluation preparation is to prepare control samples based on the evaluation objectives. In the absence of physical samples, it is necessary to rely on production knowledge and market experience to establish a consistent understanding of the quality levels and rankings of the teas being evaluated.
Step 3: Evaluating the appearance. It's important to note that the evaluation of the tenderness of sun-dried green tea differs from that of high-quality green tea. The tenderness of high-quality green tea is determined by the growth stage of the new shoots. However, Pu-erh tea is a tea that undergoes post-fermentation. According to the principles of food processing, foods with post-fermentation processes generally use raw materials of a certain maturity. For example, when making pickled vegetables, using young sprouts results in poor texture, while using mature, bolted mustard greens produces the best texture. The same applies to Pu-erh tea; tea made from larger trees with a certain degree of maturity, using one bud and two or three leaves, yields better quality. In tea gardens with poor ecological conditions, the fresh leaves of one bud and two or three leaves tend to be lignified and have many paired leaves. The resulting sun-dried green tea therefore has a withered, coarse, and light appearance. Therefore, the most important factors in evaluating the appearance of sun-dried green tea are the weight and plumpness of the tea leaves.
Step 4: Evaluating the internal quality. The evaluation of internal quality is a comprehensive assessment of the tea liquor's quality using multiple senses, including sight, smell, taste, and tactile sensations in the mouth and throat. Specifically, it includes the evaluation of four aspects: liquor color, aroma, taste, and leaf appearance after brewing.
In visual assessment, the elements considered when evaluating tea liquor are: color type and intensity, brightness and darkness, and clarity or turbidity.
The color of sun-dried tea liquor is significantly affected by the intensity of sunlight during drying and the air circulation in the drying area. The longer the drying time, the more yellow components are present; normally, the liquor should have a certain degree of greenness. Under the same processing, storage, and brewing conditions, sun-dried tea with higher brightness is considered to be of better quality. The brightness of the tea liquor is the most important factor in evaluating the color of sun-dried tea.
The sense of smell can directly evoke our memories of specific scenes and guide our emotions and behavior. During tea evaluation, whether the aroma is pleasant or unpleasant is crucial, as it directly affects our breathing, circulation, and digestive gland secretions. Furthermore, in the evaluation of sun-dried green tea, particular attention should be paid to the cold aroma. Teas with a rich cold aroma, where the fragrance is well-integrated into the liquor, tend to induce deeper breathing and a pleasant, relaxing physical experience. The elements of tea aroma evaluation include: type, concentration, purity, and persistence, assessed in three stages: hot aroma, warm aroma, and cold aroma. The degree of pleasure and persistence of the aroma are important factors in the evaluation of sun-dried green tea aroma.
In tea evaluation, "taste" refers to the broader concept of mouthfeel in food sensory analysis, encompassing the complex overall sensation resulting from the physical and chemical properties of the tea infusion stimulating taste receptors in the oral cavity and pharynx, retronasal olfaction, and mucosal tactile sensations.
Taste is divided into five basic categories: sweet, sour, salty, bitter, and umami. As we mentioned earlier, the bitterness recorded in tea tasting notes is not the same as the bitterness referred to in the context of taste receptors. The taste recorded in tea tasting notes is a holistic sensation integrated by the brain, combining retronasal aroma, oral and pharyngeal sensations, and taste. The evaluation elements include: intensity, body, freshness/dullness, mellowness/astringency, and purity/off-flavors.
The tactile sensations in the oropharyngeal region, which include touch, temperature, and pain, affect the quality of the tea.
1. Tactile Sensation: In tea evaluation, tactile sensation mainly includes the tactile sensations of the mouth and hands. The density of pressure receptors in the human body is highest in the nose, mouth, lips, and fingertips. The tactile sensation in the mouth is richer and more delicate than in other parts of the body. A thick and smooth tea liquor has a caressing effect on the oral and pharyngeal mucosa, and flows smoothly down the throat. However, a rough and astringent tea liquor will cause a certain degree of resistance when swallowed. The richness and smoothness of the tea liquor in the mouth, and the smoothness or resistance felt when swallowing, are key aspects of tactile sensation evaluation in tea tasting.
2. Temperature Sensation: Temperature receptors are distributed in the skin, mucous membranes, and internal organs, and can easily affect the sensitivity of taste and smell. At temperatures below 10°C or above 50°C, most taste sensations become dulled. The sweetness and texture of sun-dried tea are most easily perceived and compared between 22 and 32 degrees Celsius.
3. Pain: It includes both sensory and emotional components and can be modified by experience, emotions, and the immediate environment.
The flavors we perceive are the result of the brain integrating sensations from retronasal olfaction, oral and pharyngeal somatosensation, and taste. Different teas vary in the location and intensity of bitterness and astringency, the duration of these sensations, and the location and extent of the lingering sweetness and salivation. This is why teas from different regions are often easily distinguishable. The purity and richness of the aftertaste, and the feeling of comfort in the body during the aftertaste, are key elements in evaluating the flavor.
Leaf residue evaluation elements: The elasticity, luster, and thickness of the leaves are the key elements for evaluating the leaf residue of sun-dried tea.
Step 5: Quality Recording: Beginner and intermediate tea tasters learn by imitation, meticulously recording every element of each evaluation factor. Advanced tea tasters, however, learn to express the characteristics of the tea concisely and precisely in their evaluation records.
Step 6: Result calculation and comprehensive quality assessment. Based on the evaluation records, a comprehensive quality assessment is conducted to guide the production and sales of sun-dried green tea.
Sensory analysis of food is a psychological activity based on physiological processes. The process of learning about tea involves continuously stimulating the senses of touch, smell, taste, and sight through the nose, mouth, throat, hands, and eyes, forming a comprehensive perception of tea and a deep bodily memory. This is also the principle behind how professional tasters can determine the quality of tea through sipping.
What are the differences and similarities between everyday tasting and professional evaluation? We welcome you to share your thoughts in the comments section.