Performance modelling of stevioside separation using membrane processing

Abstract

The model for transport through membranes can be classified into three types: the first-generation model, second-generation model, and third-generation model. Solutes having molecular weight less than stevioside are considered to be freely permeable through ultrafiltration (UF) membrane and their hindered transport through gel layer is ignored. The UF feed contains various components, of which only stevioside is desirable. The mixture of components can be clubbed together as high molecular weight (HMW) components. Continuous cross-flow configuration is commercially more feasible and economical. An actual fruit juice or plant extract is a complex mixture of gel-forming materials and other permeable solutes. The gel layer controlling model for UF of Stevia extract for both total recycle and batch concentration modes was successfully applied in a rectangular filtration cell. Prediction of permeate flux and permeate concentration in operating mode, steady and transient conditions agreed well with the experimental data.