Abstract: The black tea infusion was separated into three phases: suspension, colloid, and the true solution by microfiltration and ultrafiltration at different temperatures. Then the concentration and distribution proportion of caffeine, total polyphenols, amino acids, and total sugars were measured. The colloidal properties were measured by Malvern. According to the sensory evaluation and the changes in contents of theaflavin, thearubigins, theabrownin, the correlations between the distribution proportion of the taste compounds, the colloid properties and the flavor of tea infusion were established. The results revealed that the proportion of taste compounds in different phases of the tea infusion was significantly different at different temperature, and the proportion of colloid/true solution could affect the size, potential of the colloidal system and the flavor. The tea infusion acquired a best sensory score by microfiltration at 50℃, while the composition distributions of colloid and true solution were 1︰3.8 for caffeine, 1.2︰1 for total polyphenols, 1︰7.5 for amino acids and 1︰4.3 for total sugars. The average particle size was 160βnm, and the Zeta potential was -25.5βmV. The 50℃ filtrated tea was mellow, rich in aroma, stable, and had uniform particle size distribution.

Key words: black tea, microfiltration, ultrafiltration, colloid, taste compounds