六堡茶茶汤中胶体颗粒及沉淀性状研究

Properties of colloidal particles and sedimentation in Liupao tea infusion

中文关键词:  六堡茶  胶体颗粒  沉淀

英文关键词:Liupao tea  tea infusion  colloidal particles  sedimentation

中文摘要:

      目的 比较六堡茶成品茶和毛茶茶汤胶体性质与茶乳酪(沉淀)的成分组成差异。方法 通过动态光散射、扫描电子显微镜和高效液相色谱法等方法比较了六堡茶毛茶以及发酵后的成品茶茶汤的胶体颗粒及沉淀性质。结果 六堡茶毛茶和成品茶茶汤中均存在胶体体系。两种茶汤冷却过程的浊度增加率逐渐减少, 接近常温(25℃)时, 成品茶茶汤浊度增加率小于毛茶; 两种茶汤中存在球形或椭球形的胶体颗粒, 且胶粒粒径与Zeta电位具有温度响应。25℃下成品茶茶汤的胶体颗粒平均粒径(2131.0 nm±144.2 nm)低于毛茶(3045.8 nm±67.9 nm), 成品茶茶汤Zeta电位(?24.8 mV±0.8 mV)高于毛茶(?19.2 mV±0.2 mV)。两种茶汤成分差异导致二者沉淀差异, 成品茶固形物相对沉淀率(2.22%)小于毛茶(2.79%), 成品茶沉淀主要成分为茶红素、蛋白质和多糖, 占沉淀总量58.83%, 毛茶则为多酚、蛋白质和多糖, 占沉淀总量75.76%, 两种茶汤沉淀中酯型儿茶素总量均高于非酯型儿茶素总量, 其酯型儿茶素、蛋白质、多糖和黄酮较易参与沉淀形成。结论 发酵使成品六堡茶的茶汤的胶体颗粒稳定性增加, 使其形成的茶乳酪与发酵前存在明显差异。本研究为黑茶饮料等食品的开发提供了理论基础。

英文摘要:

      Objective To compare the differences of colloidal properties of Liupao tea and raw tea infusion and the composition of tea cream (sedimentation). Methods Compared the properties of colloidal particles and sedimentation in raw tea and fermented tea infusion using dynamic light scattering, scanning electron microscope, and high performance liquid chromatography. Results The results demonstrated the presence of colloidal system in both raw tea and Liupao tea infusions. The increase rate of turbidity of Liupao tea and raw tea showed a gradual decrease during the cooling process. As the temperature approached room temperature (25℃), the increase rate of turbidity of Liupao tea was smaller than that of raw tea. Furthermore, both infusions of Liupao tea and raw tea contained spherical or ellipsoidal colloidal particles, and the particle size and Zeta potential of these colloidal particles showed temperature-dependent responses. At 25℃, the average particle size of colloidal particles in Liupao tea infusion (2131.0 nm±144.2 nm) was smaller than that in raw tea infusion (3045.8 nm±67.9 nm), and the Zeta potential of Liupao tea infusion (?24.8 mV±0.8 mV) was higher than that of raw tea (?19.2 mV±0.2 mV). The difference in composition between the 2 kinds of tea infusions resulted in variations in sedimentation. The relative sedimentation rate of solids content in Liupao tea (2.22%) was smaller than that in raw tea (2.79%). The main components contributing to sedimentation in Liupao tea were thearubigins, proteins, and polysaccharides, accounting for 58.83% of the total sedimentation. In contrast, polyphenols, proteins, and polysaccharides accounted for 75.76% of the total sedimentation in raw tea. The sedimentation of both tea infusions showed a higher total amount of ester-type catechins compared to non-ester-type catechins. Ester-type catechins, proteins, polysaccharides, and flavonoids were more readily involved in the formation of sedimentation. Conclusion Fermentation increases the stability of colloidal particles in the Liupao tea infusion, resulting in significant differences in the tea cream compared to before fermentation. This finding provide a theoretical basis for the development of dark tea beverages and other food products.