Determination of total phenolic compounds in plant extracts via Folin-Ciocalteu’s method adapted to the usage of digital images

Abstract

The food industry shows great interest on researching innovative and alternative methods to determine phenolics compounds’. Hence, the present study aims to develop a technique based on Folin-Ciocalteu’s method to determine the total amount of phenolic compounds of a sample using a smartphone as a tool for obtaining digital images of the analysis’ and evaluating them through the Colorgrab^® application. In this study, color parameters S, L, V and I were evaluated, as well as experimental parameters such as distance between sample and camera, light temperature, and sample’s volume. To improve analytical conditions, phenolic compounds were determined through the conventional Folin-Ciocalteu’s method, with the results being compared to the data obtained from the adapted method. After optimization, the procedure was carried out using the S color parameter, cold light (6500 K), 7 cm distance between sample and camera, and a solution volume of 1.5 mL. The test showed suitable results for precision (RSD < 2.4%) and accuracy (98.4 to 103.8%) when compared to the conventional method. The proposed technique proved to be an innovative alternative to determine total phenolic compounds in routine analysis for different sectors of the food industry, showing good analytical results without requiring sophisticated equipment.

Practical Application: This study sought to develop an analytical method through the use of digital images obtained from a smartphone as an easily available alternative to quantify a sample’s total phenolic compounds. This technique aims to replace the use of a spectrophotometer; reducing the need for bulky equipment; as well as reducing environmental impacts by using less solvents; all while proposing a technique with relatively lower cost compared to those commonly used and following the recommendations of green chemistry