Tea in color: Single-probe nanozyme array for multichannel visual fingerprinting and portable quality evaluation

Area of Science:

• Analytical Chemistry
• Materials Science
• Food Science

Background:

• Growing consumer demand for authentic, high-quality green tea necessitates reliable, practical evaluation methods.
• Existing methods for tea quality assessment can be complex and time-consuming.
• Bioactive polyphenols are key indicators of green tea's quality and health benefits.

Purpose of the Study:

• To develop a simple, reliable colorimetric sensor array for discriminating tea polyphenols and assessing green tea quality.
• To enable practical, on-site evaluation of green tea type, freshness, and adulteration.
• To integrate nanozyme catalysis with smartphone imaging for accessible quality control.

Main Methods:

• Development of a colorimetric sensor array utilizing 3,3',5,5'-Tetramethylbenzidine (TMB) and bimetallic platinum-palladium nanoparticles (B-PtPd_NPs).
• Utilizing the oxidase-mimicking catalytic activity of B-PtPd_NPs for efficient TMB oxidation under ambient conditions.
• Smartphone imaging to capture colorimetric changes, followed by RGB value extraction and linear discriminant analysis for data interpretation.

Main Results:

• The sensor array generated distinct spectral responses (370, 450, 650 nm) reflecting the redox behavior of different tea polyphenols.
• Accurate classification of five major polyphenols, their mixtures, and green tea samples based on type and storage history.
• Successful identification of adulterated Biluochun tea, demonstrating the system's effectiveness in authenticity testing.

Conclusions:

• The developed nanozyme-based colorimetric sensor array offers a robust and user-friendly strategy for tea quality assessment.
• Integration with smartphone technology provides a portable and accessible platform for on-site analysis.
• This approach holds significant promise for practical quality control and authenticity verification in the tea industry.