Kinetics and mechanistic models of solid-liquid extraction of pectin using advance green techniques- a review

Abstract Pectin as a hydrocolloid has countless functional applications in food and related industries. The extraction techniques considerably influence the composition, characteristic and extractability of the target compound, hence there is an ongoing effort to understand the extraction process using theoretical approaches. This review aims to provide a comprehensive overview of different mathematical approaches reported for describing the solid-liquid extraction process for pectin. As the major source of pectin is citrus waste, the extraction techniques described in this review article have considered citrus processing waste as a major substrate. Chemical rate law, empirical models and mechanistic approaches have been considered in the study. The modelling approaches are based on the hydrolysis, diffusion and degradation of pectin in a homogenous medium, and have been described either as a single or combination of more than one phenomenon. The application of models has been critically reviewed with respect to the influence and interdependencies of the parameters on the extraction kinetics with reference to advance green techniques such as subcritical water, microwave and ultrasonic-assisted extraction processes. Understanding of these models can be used to successfully to predict the properties of extraction systems at a phenomenological scale.