| dc.description.abstract | The production of tea dregs is continually increasing along with the growth of people's interest in ready-to-drink beverages.
However, the recent development of research on the use of tea dregs is still very limited. The present study was aimed to
identify the remnant photosynthetic pigments in tea dregs, determine their composition, and evaluate their potential use as
natural antibacterial agents based on light-induced reaction (photosensitization). The tea dregs from six commercial teas,
consisting of green and black teas, were analyzed using high-performance liquid chromatography (HPLC) with a photodiode
array detector, and the spectroscopic data were analyzed from 350 to 700 nm. Pigment identification was performed based
on spectral characteristics, and pigment composition in the extracts from the dregs was determined by a three-dimensional
multi-chromatogram analysis method. The dominant pigment fractions in both tea types were pheophytin a and its isomers,
as well as pheophytin b. Although the dregs of black teas generally contain fewer remnant pigments, they possess residual
chlorophyll b, which is not found in the dregs of green teas. In thirty-minutes illumination under 50 W red light-emitting
diode, the presence of pigments from tea dregs caused up to 0.87 and 0.35 log reduction of Staphylococcus aureus and
Escherichia coli, respectively. The disparity of pigments composition among tea types does not strongly influence their
photosensitization activity against both bacteria. Hence, upon further application, the amount of total remnant pigments in
the dregs could be taken as substantial consideration instead of tea types. | en_US |
