Fast, sensitive, and sustainable colorimetric detection of chlorogenic acid in artichoke waste material

Caffeoylquinic acids (CQAs) are nutraceutical polyphenols highly represented in natural sources, including artichoke waste (AW). In this study a colorimetric method for rapid and sustainable detection of a 5-CQA isomer (Chlorogenic acid) in AW extract was developed by using alkaline Tris buffer (10 mmol L^-1, pH 9) to generate a yellow color associated with 5- to 3-CQA isomerization reaction, as suggested by NMR and MS analyses. The strong absorbance at 360 nm was followed by standard UV-Vis methodology. The colorimetric assay was exploited for detection of 5-CQA into leaf extract from artichoke, obtaining a value of 15.2 ± 0.3 μg/mg of dry extract, in agreement with HPLC analysis (14.3 ± 0.7 μg/mg, 106 ± 2 % recovery) used as validation technique, with excellent linear correlation and precision (R² = 0.9996, _avRSD% = 3.2 %). The method is fast and selective, offering a valuable tool for nutraceuticals identification and food waste valorization.