Optimization of the Ultrasound-Assisted Extraction of Anthocyanins from Acerola (Malpighia emarginata) Using Response Surface Methodology

Abstract The extraction of anthocyanins from acerola ( Malpighia emarginata ) has potential for obtaining bioactive compounds, and ultrasound-assisted extraction (UAE) is an alternative to conventional methods. In this study, the kinetics and the influence of operating variables on the total anthocyanin content (TAC) obtained by UAE were investigated. Extraction was performed in an ultrasonic bath at 40 kHz, using an extraction solvent of 95% ethanol and 1.5 mol L − 1 HCl at an 85:15 (v/v) ratio. Extraction kinetics were evaluated using Fick’s Law, the Power Law, and the Peleg model, while the experimental conditions were optimized through statistical analysis of a Box-Behnken design. TAC was determined by the single pH method at 535 nm. Among the kinetic models, the Peleg model showed a satisfactory fit to the experimental data, with R 2 > 0.99 and RMSE = 0.1975, indicating the relevance of diffusion in the mass transfer process. In the experimental design, TAC ranged from 9.32 to 25.46 mg/100 g. ANOVA indicated a significant effect of the linear term of the solid/liquid ratio ( p = 0.0012) and of the quadratic terms of temperature ( p = 0.0065) and time ( p = 0.0151). The quadratic regression model showed R² = 0.9403 and a non-significant lack of fit ( p = 0.2633). The maximum response predicted by the model was 27.45 mg/100 g, associated with a temperature of 38.8°C, a time of 7.87 min, and a solid/liquid ratio of 0.02 g/mL. The results revealed that combining kinetic modeling and optimization is a suitable approach for understanding the ultrasound-assisted extraction of anthocyanins from acerola.