Rapid Quality Evaluation and Market Valuation of CTC Black Tea Using Near-Infrared Spectroscopy

Abstract

The market success of Crush–Tear–Curl (CTC) black tea depends largely on rapid and reliable methods of quality evaluation. Despite advances in tea processing, the assessment of CTC black tea quality is still dominated by time-intensive chemical testing and sometimes subjective tasting, underscoring the need for rapid, objective alternatives. This study shows that Near Infrared (NIR) spectroscopy can provide fast, non-destructive, and objective predictions of tea liquor, infusion, overall quality, and theaflavins (TF). Using CARS–PLSR and Random Forest models, strong prediction performance was achieved (RPD > 3.0). Random Forest gave the most accurate liquor assessment, while CARS–PLSR excelled for infusion and TF. These findings suggest that portable NIR devices, when combined with robust modelling, could support faster and more objective grading in tea factories, auction centres, and quality-control laboratories. Rather than replacing traditional sensory and chemical evaluations, this approach offers a practical supplement that may improve efficiency, transparency, and consistency across the tea value chain.
Keywords: NIR, Theaflavin, liquor-infusion-quality (LIQ), PLSR, RF, CARS