The description of green tea taste evaluation usually uses terms such as bitterness, richness, richness, freshness, and coarseness.
There are generally three types of substances that make up these taste characteristics, namely polyphenols, amino acids, and sugars. The taste characteristics of polyphenols are "bitter" and "astringent", amino acids are "fresh and refreshing", and sugars are "sweet and mellow".
Polyphenols account for 20% to 30% of the dry matter content in fresh leaves, with catechins being the main component. Catechins can be divided into two parts: simple and complex catechins. From various catechin variables, the content of simple catechins increases with the development of new shoots, while complex catechins are the opposite.
Fresh leaves contain approximately 1% to 3% of free amino acids, which play an important role in green tea. Among them, theanine accounts for 50%~60% of the total amino acid content in new shoots, which has a significant impact on quality.
Pure polyphenols are bitter, while pure amino acids only have a fresh taste. The combination of the two gives a "refreshing" tea flavor. Therefore, the ratio of polyphenols to amino acids can better reflect the taste of green tea. Low proportion tea has a fresh and refreshing taste, while high proportion tea has a strong and astringent taste. Polyphenols are higher in summer tea than in spring tea, while amino acids are exactly the opposite. Summer tea is lower than spring tea, so spring tea is fresh and refreshing while summer tea is bitter.
Soluble sugars are sweet substances, with fresh leaves containing approximately 1% to 2%.
