Comparative assessment of tea quality by various analytical and sensory methods with emphasis on tea polyphenols

Attempts were made to evolve an efficient
technique for quality assessment of tea (Camellia sinensis)
using a tyrosinase based biosensor to detect polyphenols
(PP). Tyrosinase catalyzes the polymerization of PP to form
theaflavins (Tf) and thearubigins (Tr) contributing to the
colour and astringency of tea, which determine tea quality.
Variation in biosensor response of tea infusions gave an
indication of differential amount of Tf and Tr. A comparative
study of quality attributes of 8 varieties of commercially
available brands of tea (A–H) was done using
biosensor and results were compared with conventional
techniques such as spectrophotometry, high performance
liquid chromatography (HPLC), Commission Internationale
de I’Eclairage (CIE) system and sensory evaluation.
Considerable correlation was observed among the biosensor,
sensory and spectrophotometric evaluation of tea samples.
Sample A showed high Tf content and also showed a relative
high biosensor response whereas sample G showed relatively
poor response. Application of biosensors would serve as a
basis for the evaluation of market value of tea in the near
future.