Membrane Clarification of Black Tea Extracts

Abstract

Microfiltration (MF; 200 and 450 nm) and ultrafiltration (UF; 25, 50, 100 and 500 kDa) membranes were assessed for the clarification of black tea extracts. Rejection of tea components including cream components increased with decrease in membrane pore size. Clarity of membrane processed extracts was excellent (∼4 Nephelometric Turbidity Units) even after 30 days of refrigerated storage. UF-500 and MF membranes resulted in greater retention of original colour, besides greater recovery of tea solids including polyphenols in the clarified extract. Increase in feed concentration affected the recovery while diafiltration improved the solids recovery including polyphenols and theaflavins. Highest productivity was achieved at 2 % feed concentration followed by 0.6 %. Solids and polyphenols recoveries obtained with 0.6 % feed concentration and MF-450 membrane combination were unmatched with any other combination. The results favoured employing MF as a means of clarification of tea extracts, preferably at low feed concentration which provided greater recovery and productivity, adequately meeting the quality requirements of ready-to-drink tea beverages.