茶多酚和咖啡碱对茶乳酪形成的影响

采用茶多酚和咖啡碱模拟构建茶乳酪成因体系，通过分析溶液的透光率、粒径、沉淀量、咖啡碱和儿茶素含量的变化，综合评价茶多酚和咖啡碱对茶乳酪形成的影响。结果表明：随茶多酚和咖啡碱质量浓度的增加，其聚合后溶液的透光率从95.5%降为24.7%；粒径从198 nm增加到475 nm；沉淀量由8 mg/L增加到244 mg/L；当固定咖啡碱或茶多酚中任一物质的质量浓度，随另一物质质量浓度的增加，上述变化趋势增强。通过分析检测咖啡碱和儿茶素各单体在模拟反应体系中的变化，表明咖啡碱和表没食子儿茶素没食子酸酯（epigallocatechin-3-gallate，EGCG）是模拟体系中茶乳酪形成的关键组分。因此，尽量选用咖啡碱含量低于200 mg/L、茶多酚含量低于1 200 mg/L的绿茶原料，可避免茶乳酪的大量生成，增强绿茶饮料透亮的感官效果。

Effects of Different Concentrations of Caffeine and Tea Polyphenolic Compounds on the Formation of Tea Cream

A model system consisting of tea polyphenols and caffeine was set up for studying the formation mechanism of
green tea cream. The transmittance, particle size, amount of tea cream, caffeine and catechins contents of the solution were
investigated to study the effects of different concentrations of polyphenols and caffeine compounds on the formation of tea
cream. The results showed that the transmittance of the solution was decreased from 95.5% to 24.7%, the particle size was
increased from 198 to 475 nm and the amount of precipitate was increased from 8 to 244 mg/L with increasing addition of
polyphenols and caffeine. These changing trends were more pronounced with increasing concentration of one of the two
components at a constant level of the other. High performance liquid chromatography analysis of the contents of caffeine and
catechins showed that caffeine and EGCG were the main compounds of tea cream. Based on our results, green tea infusion was relatively
more stable when polyphenols concentration was lower than 1 200 mg/L and caffeine concentration lower than 200 mg/L.