Enrichment of (−) epigallocatechin gallate (EGCG) from aqueous extract of green tea leaves by hollow fiber microfiltration: Modeling of flux decline and identification of optimum operating conditions

Polyphenols are the important phytochemicals available in green tea leaves and epigallocatechin gallate (EGCG) is the most active one. A scalable method to enhance purity of EGCG from two stage aqueous extract from green tea leaves using hollow fiber microfiltration is reported in this work. Experiments were conducted in the range of 35 to 172 kPa transmembrane pressure drop and cross flow rate 10 to 30 l/h. The flux decline during filtration was quantified using a simple resistance in series model. A first order kinetic model adequately described the growth of fouling layer with time of filtration. A generalized criterion on locus of limiting flux with operating conditions (limiting transmembrane pressure and Reynolds number) was derived and the envelope of optimum operating conditions was identified. Limiting transmembrane pressure was 147 kPa at Reynolds number 282 and the limiting permeate flux at these conditions was 93 l/m2 h. About 80% purity of total polyphenol content and 75% purity of EGCG were attained in the permeate. This work provided a basis for production and purification of green tea polyphenols in industrial scale.