Ultrasound-assisted extraction of phytocompounds from dragon fruit peel: Optimization, kinetics and thermodynamic studies

Ultrasound-assisted extraction method (UAE) was applied to recover phytocompounds from dragon fruit peel and the process was modelled and optimized using the combination of artificial neural network (ANN) and genetic algorithm (GA). The influence of ultrasonic temperature (30-70 degrees C), solvent to solid ratio (10:1-30:1 mL/g), solvent concentration (30-60%), and ultrasonic treatment time (5-25 min) on total polyphenolic content (Z(T)), antioxidant activity (Z(D)) and betacyanin content (Z(B)) was investigated. The ANN model successfully fitted to the experimental data and the output of ANN model was applied for genetic algorithm optimization. The optimal UAE conditions were obtained at ultrasonic temperature of 60 degrees C, solvent to solid ratio 25:1 mL/g, solvent concentration 60%, and ultrasonic treatment time of 20 min. The extraction kinetics and thermodynamic study for phytochemical compounds extracted from dragon fruit peel using UAE process was carried out at different combinations of temperature and time of extraction. The effective diffusion coefficient for total polyphenol content, antioxidant activity and betacyanin content were ranged from 2.99 x 10(-11) to 4.84 x 10(-11) m(2)/s, 1.89 x 10(-11) to 4.51 x 10(-11) m(2)/s and 2.55 x 10(-11) to 5.40 x 10(-11) m(2)/s respectively and the corresponding mass transfer coefficient were varied between 2.00 x 10(-06) - 2.81 x 10(-06) m/s, 1.53 x 10(-06 )- 2.66 x 10(-06) m/s and 1.81 x 10(-06 )- 3.05 x 10(-06) m/s respectively. The obtained information on effective diffusivity and mass transfer coefficient during extraction would allow the prediction of extraction rate and for estimation of operation conditions for industrial implementation.