Impact of light irradiation on black tea quality during withering

Abstract

Black tea manufacture usually involves the processes of withering, cutting, fermentation and drying. The aim of present study was to evaluate the effect of the relationship between the quality and withering with different light sources (ultraviolet, yellow, blue, purple, orange, red, cyan, green and white) an quality attribute of tea. The results indicated that the yellow, orange and red light withering significantly improved the aroma and taste, imparting the tea a sweet flavor and a fresh and mellow taste. Tea treated with yellow light was scored highest the sensory scores and showed the highest content in catechins, theaflavins, amino acids and aroma components, followed by the orange and red light treatments. The black tea withered with ultraviolet light showed a strong astringency, probably resulting from low contents of theaflavins, amino acids and soluble sugar. The green light irradiation remarkably damaged the aroma and taste of the tea, leading to a strong greenish flavor and an astringent taste, probably owing to the lowest contents of chemical compositions. No significant cumulative effect was found in the hybrid light withering treatments. Therefore, monochromatic yellow, orange and red lights were suggested for withering the black tea to improve its overall quality.

Inhibition of the facilitative sugar transporters (GLUTs) by tea extracts and catechins

“…Catechins were determined by high performance liquid chromatography (HPLC) at Finlay Tea Extracts Ltd, UK, as described by in our previous work. 32 Briefly, the tea extract powders (0.2 g) were resolved with 10 mL of 70% methanol (vol/vol), then, the solution was filtered through a 0.45 μm membrane. The separation was performed on an ODS reversed-phase column (4.6 mm i.d.…”

Review: the effect of light on the key pigment compounds of photosensitive etiolated tea plant

“…Light has an important effect on plant leaves before and after in vitro. Different LED monochromatic are carried for pre-harvest and pro-harvest the fresh leaves of tea plant to improve flavor of tea (Ai et al 2017 ; Lee et al 2013 ). Light is particularly important for the physiological development of leaves of photosensitive etiolated tea plant, under high light intensity, the grana of chlorotic tea plant that “Baijiguan” is scarce, and the structure and interval of thylakoid membrane system are destroyed (Wu et al 2016 ).…”

Effect of red light on the composition of metabolites in tea leaves during the withering process using untargeted metabolomics

“…15 Red light withering (630-640 nm) has also been shown to significantly improve the aroma of tea and impart a sweet, fresh, mellow taste. 16 It is widely accepted that red light can improve the sensory quality of black tea when it is used in withering processing. However, there have been few systematic studies of red light withering on metabolites in tea leaves, which limits the understanding of how changes in metabolites during the withering process are influenced by red light, as well as knowledge of the relevant mechanism.…”