Extraction kinetic modelling of polyphenols from artichoke bracts using a system with continuous detection by Ultraviolet–Visible monitoring

Abstract This research focuses on the aqueous extraction kinetics of total phenolic content (TPC) from artichoke, using a novel extraction system with continuous detection (ESCD). This system enables high-resolution kinetic data acquisition (1 count per second) using an online Ultraviolet–Visible (UV) spectrophotometer. For the extraction process, “Blanca de Tudela” artichoke bracts (diameters from 7.8 to 8.2 cm) were used. During the experiments, different stirring speeds (300–500 rpm), particle sizes (2–8 mm), solid–liquid ratios (1/20–1/50), and temperatures (20–60 °C) were employed. The findings showed that temperature had the most considerable effect on the extraction process. The experimental kinetic data showed a linear correlation (R2 = 0.995) between the absorption band located at 255 nm and TPC. In tests 7–9, the TPC extraction behaviour exhibited a high correlation with the supra-diffusion Simpson’s model, with R2 ranging from 0.994 to 0.999. The extraction time was determined using the extraction rate of 4.18 ± 0.00436 × 10−3 min−1. Finally, the antioxidant activity kinetic model showed a high correlation (R2 = 0.99) when the constants k₁, k₂, and n from the TPC concentration model were applied. Therefore, the ESCD has been shown to be useful for studying and developing effective TPC extraction.