Alpha_Quantitative Determination of Total Polyphenol Content in Green Tea Powder

In this study, the total polyphenol content of a green tea powder used for food manufacturing was quantified using the ISO 14502-1:2005(E) standard analytical method. A 70% methanol extract of the sample was reacted with Folin-Ciocalteu reagent, and the absorbance was measured at 765 nm using the Alpha UV-Vis spectrophotometer, after which the results were expressed as gallic acid equivalents (GAE) based on a gallic acid calibration curve. The calibration curve constructed over the range of 10.0–50.2 μg gallic acid showed excellent linearity, with a correlation coefficient (R²) of 0.9999. These findings demonstrate that total polyphenol analysis performed with the Alpha UV-Vis spectrophotometer is compliant with the ISO 14502-1 test method and can be reliably applied to the quantitative determination of total polyphenols in food-grade raw materials.