A simple paper-based colorimetric biosensor based on immobilized tyrosinase and 3-methyl-2-benzothiazolinone hydrazone (MBTH) was developed for assessing total polyphenol content (TPC) of various green tea beverages. The patterned biosensing zone of the paperbased biosensor showed a sensitive response to catechin (a typical green tea polyphenol) by generating pink color adducts that can be captured for further color image analysis using a scanometric method. This color change can be connected to the TPC of the samples. The analytical performance of the biosensor in scanometric set-up was optimized. The biosensor showed a response time of 13 min in the linear range between 0.08-1.03 mM of catechin (r = 0.9979). The detection limit (LOD) of the biosensor was 0.071 mM while reproducibility was found at 3.11% RSD (relative standard deviation). TPC of green tea beverages was assessed by the biosensor, and the results were in accordance with the UV/Vis spectrophotometric method.
- green tea