Anthocyanins are antioxidant and anti-inflammatory ingredients in various fruit beverages, for which their conservation and quantitation are important for the food industry. In this paper, we report a simple, portable device for accurate on-site determination of total monomeric anthocyanins in fruit beverages employing a Wi-Fi scanner coupled with a flexible microchip and a free mobile app. The detection principle is based on the pH-induced colorimetric reactions of anthocyanins performed in a specially designed microchip and validated with standard spectrophotometric measurements. The microchip with multiple testing vials was prepared with the benchtop molding method with a common PDMS elastomer and a transparency film; the photo of the scanned microchip is wirelessly sent to a smartphone and the RGB values of individual reaction vials in the microchip are analyzed with a free mobile app to determine the corresponding concentrations. It was demonstrated that the quantitation performance of this POCT device is comparable with conventional spectrophotometry in the determination of total anthocyanins in both standard solutions and fruit beverages.
Keywords: Wi-Fi scanner; anthocyanin; colorimetry; mobile app; on-site detection.