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Polyphenol composition in black tea plays an important role in antioxidant potential, sensory qualities, and overall health benefits. To determine the quality of the tea, it is important to know the levels of the different polyphenol compositions in the various regions where tea is cultivated. The total polyphenol content (TPC) of "Broken Orange Pekoe Fannings" (BOPF) grade black tea was measured and compared in this study. The reason BOPF was chosen as the study grade because of its fine particle size, which guarantees effective extraction and yields reliable and reproducible analytical measurements. The most common tea grade in tea bags and blends is also BOPF. The tea samples were collected from five major Sri Lankan tea-growing regions: Sabaragamuwa, Dimbula, Ruhuna, Udu Pussellawa, and Uva. To provide statistically representative data, ten factory-grade samples were collected from each region. All the samples were subjected to the same laboratory processing, where dry matter content was calculated according to ISO 1572, and TPC (% dry weight) was evaluated using the standard Folin-Ciocalteu method (ISO 14502-1:2005(E)). The results showed noticeable regional differences in chemical composition
The mean (±SD) TPC values were: Sabaragamuwa 18.98 ± 0.39, Dimbula 17.62 ± 0.92, Ruhuna 24.31± 1.98, Udu Pussellawa 19.34 ± 1.35, and Uva 15.38 ± 1.36 % DW. Ruhuna tea displayed the highest polyphenol concentration, while Uva recorded the lowest. Dry matter content also displayed regional differences: Sabaragamuwa had the highest value at 94.60 ± 0.70 %, followed by Uva (93.85 ± 1.09 %), Udu Pussellawa (92.66 ± 0.72 %), and Ruhuna (91.91 ± 0.88 %), while Dimbula showed the lowest dry matter at 90.92 ± 0.51 %.
These variations show the influence of regional agro-climatic conditions such as elevation, rainfall, soil chemistry, and temperature, as well as processing differences at the factory level. Overall, these combined TPC and dry matter profiles offer different chemical signatures for every region, providing significant potential for the development of analytical and sensor-based tools that can identify and verify the geographic origin of Sri Lankan black tea, supporting enhanced quality assurance and region-specific branding.
Key Words: Total polyphenol content; BOPF black tea; Dry matter content; Regional variation; Sri Lankan tea
