Creaming in black tea.

Tea cream is the precipitate formed as tea cools. Its formation has been studied by X-ray scattering, and it is shown that a higher tea concentration leads to earlier onset of creaming and larger particles and that addition of theaflavin and calcium promotes creaming. Association constants between the major components of black tea have been obtained using NMR and show that calcium and glucose enhance the self-association of caffeine, polyphenols, and theaflavin but have little effect on hetero-association.

Polyphenol/peptide binding and precipitation.

Polyphenols are largely responsible for the astringency and "mouthfeel" of tea and wine by their interactions with basic salivary proline-rich proteins. Astringency arises from precipitation of polyphenol/peptide complexes, which is an important protective mechanism in animals that consume polyphenols. This paper presents biophysical studies of the interactions between chemically defined polyphenols and peptides.