Rapid test for the determination of total phenolic content in brewed-filtered coffee using colorimetric paper

This work was aimed to develop a chemical sensor for the determination of total polyphenol content (TPC) of coffee samples. The polyphenol sensor was based on co-immobilization of NaIO₄ and MBTH in paper as a test strip. The sensor showed sensitive response to chlorogenic acid by forming pink color adduct which can be scanned and quantified by Imagej program. The sensor had response time of 14 min and a linear range between 0.07 and 0.71 mM of chlorogenic acid with a detection limit at 0.002 mM toward chlorogenic acid. The reproducibility of the sensor was good (RSD = 0.44%) with a life time within 27 days when stored at 4 °C. TPC of coffee samples were determined by the sensor, and the results were in agreement with the Folin-Ciocalteu method suggesting its practical use as a tool for TPC determination in coffee samples.