Another perspective to explain green tea cream: Utilizing engineered catechin-caffeine complex

Green tea cream, the precipitate formed in cooled green tea infusion, appears a negative effect on flavor. To explain the mechanism of green tea cream, complexations between four catechins (CATs) and caffeine (CAF) were engineered and characterized. Dynamic light scattering, high performance liquid chromatography, scanning electron microscopy, fourier-transform infrared spectroscopy, UV–visible absorption spectrum, and x-ray diffraction were used to reveal the differences between ester catechins and non-ester catechins in the dynamic complexation process, particle shape, and precipitate mechanism with caffeine. The results indicated that CATs and CAF affected each other's microenvironment in aqueous solution and Guanidine hydrochloride (GH) weakened the effect both in solution and precipitate. In addition, the 1:1 complex structure of EGC-CAF was first proved, the hydrogen bond, CH…π and π…π interaction were the forces of CAT-CAF complexes by XRD. These results provided a new perspective to the mechanism analysis of green tea cream.