Quality Variations on Pu-erh Tea in Gan-Pu Tea Stored for Different Lengths of Time

Objective Variations in quality of the Pu-erh tea contained in Gan-Pu Tea produced in five consecutive years were determined by sensory evaluation and biochemical analysis.

Method Sensory quality of the Pu-erh tea contained in the Gan-Pu Tea produced in the years from 2017 to 2021 was evaluated, and catechins, caffeine, free amino acids, water extract, tea polyphenols, soluble sugars, and pigments analyzed. Fungi grown on the samples after years of storage were identified by morphological observation and molecular methods.

Result The total catechins in the puer tea decreased gradually with increasing storage years. The Pu-erh tea contained in the Gan-Pu Tea made in 2017 had 46.78% less catechin, 25.28% less polyphenols, 64.70% less aspartic acid (Asp), and 35.71% less glutamic acid (Glu) than in the product made in 2021. There were no significant differences in the pigment (e.g., chigorgenin, thearubigin, and theaflavin), soluble sugar, and caffeine contents of the pu-erh tea in the products made in different years. On the other hand, the dominant fungus, Aspergillus, in the tea increased in number with the storage time.

Conclusion The biochemicals in the Pu-erh tea contained in Gan-Pu Tea dissipated in storage. However, an aged tea was more mellow in taste.