Effect of Yellowing Duration on the Chemical Profile of Yellow Tea and the Associations with Sensory Traits.

The yellowing process is the crucial step to form the characteristic sensory and chemical properties of yellow tea. To investigate the chemical changes and the associations with sensory traits during yellowing, yellow teas with different yellowing times (0-13 h) were prepared for sensory evaluation and chemical analysis. The intensities of umami and green-tea aroma were reduced whereas sweet taste, mellow taste and sweet aroma were increased under long-term yellowing treatment.

Widely targeted metabolomics analysis of white peony teas with different storage time and association with sensory attributes.

The sensory features of white peony teas (WPTs) significantly change with storage age; however, their comprehensive associations with composition are still unclear. This study aimed to clarify the sensory quality-related chemical changes in WPTs during storage. Liquid chromatography-tandem mass spectrometry based on widely targeted metabolomics analysis was performed on WPTs of 1-13 years storage ages.

Differential behaviors of tea catechins under thermal processing: Formation of non-enzymatic oligomers.

Tea catechins as a member of flavan-3-ols subclass with the same skeleton may behave differentially. This study investigated the chemical conversions of 8 catechins under heat treatment with the involvement of epimerization, hydrolysis and oxidation/condensation reactions. Three reactions were enhanced as temperature increased from 30 °C to 90 °C.

Adsorption behavior of the catechins and caffeine onto polyvinylpolypyrrolidone.

Adsorbent is one of the most important factors for separation efficiency in fixed-bed purification techniques. The adsorption behavior of catechins and caffeine onto polyvinylpolypyrrolidone (PVPP) was investigated by static adsorption tests. The results showed that catechins rather than caffeine were preferred to adsorb onto PVPP since the adsorption selectivity coefficient of total catechins vs caffeine was around 22.