SOME MOLECULAR AND COLLOIDAL ASPECTS OF TEA CREAM FORMATION

The formation of tea cream for a range of black tea materials was stud ied by turbidity measurements, time-resolved light scattering, gravime tric measurements and High Performance Liquid Chromatography (HPLC). T hese techniques demonstrate that, in the absence of caffeine and/or ga llate esters the solubility of tea solids in black tea infusions is en hanced compared with the 'standard' black tea material. All the tea sy stem show an increase in cream-point, amount of tea cream and particle size with increasing tea solids concentration. Decaffeination has a l arger impact on enhancing the solubility of tea colloids than degallat ion. HPLC studies indicate that theaflavins have a preference for the cream phase, whereas ie. catechin C is preferentially partitioned into the aqueous supernatant phase. Caffeine is preferentially partitioned into the cream phase, albeit less favourably than theaflavins and oth er relatively high-molecular mass polyphenols. Comparison between 'sta ndard' and decaffeinated black tea shows that in the absence of caffei ne, epigallocatechin gallate (EGCG) is preferentially partitioned into the cream phase. (C) 1998 Elsevier Science Ltd. All rights reserved.