Comparative study of cream in infusions of black tea and green tea [Camellia sinensis (L.) O. Kuntze]

Particle size, concentration and chemical composition of green-tea cream and black-tea cream were studied. Tea-cream particle size tended to decrease during tea fermentation and average size of tea-cream particles was bigger for green than for black tea. The amount of tea-cream formed in tea infusions depended on their chemical composition. Tea catechins and their oxidation products formed tea-cream when they interact with some non-catechin compounds in tea liquor. Model fermentation tests revealed that little tea-cream was found in solution of crude tea catechins and the tea-cream formed after fermentation did not significantly increased in the crude tea catechins solution. Tea extract prepared at 50 degreesC formed less tea-cream than those prepared at 90 degreesC before and after fermentation. Caffeine, gallocatechin (GC) and epigallocatechin gallate (EGCG) were the predominant compounds in green-tea cream but thearubigins (TRs), caffeine and theaflavins (TFs) in black-tea cream. Gallated catechins and gallated TFs had stronger creaming ability than un-gallated catechins and TF. How to control tea liquor from creaming down is discussed.