Kinetic modeling of pectin extraction by ultrasound assisted and conventional methods

The goal of this study was to investigate the most suitable kinetic models for pectin extraction by way of ultrasound-assisted extraction (UAE) and conventional heating extraction (CHE) with acid from melon peel. The ultrasound and acidic assisted extraction were performed on powdered melon peel in three different temperatures of 40-55-70°C and 50-70-90°C, respectively. It was observed that, in the UAE method, pectin yield increased significantly in a shorter time compared to CHE which reached its peak at a lower temperature so UAE can be considered as more reasonable method. The experimental data (pectin yield versus time) were suited to a variety of kinetic models by linear regression. The total extract yields from melon peel by UAE and CHE among five conditions displayed the closest fit in the condition of pH=2 at temp 55 ˚C to the power law model (R2 = 0.92) and in the condition of pH=2 at temp 70 ˚C to the parabolic diffusion model (R2 = 0.94), respectively. The theoretical models expressed the extractability, dissolution and degradation rates of pectin, and investigated the extraction kinetics. When ultrasound and acidic procedures were applied simultaneously a synergetic effect between heating and extractability, dissolution and degradation of pectin was observed leading to a higher yield (34.18%), extractable pectin (37.45%), degradation rate (0.23%), dissolution rate (5.37%), with a shorter extraction time (61.28 min).