Tea polyphenols (TP) are a widely acknowledged bioactive natural product, however, low stability and bioavailability have restricted their application in many fields. To enhance the stability and bioavailability of TP under certain moderate conditions, encapsulation technique was applied. Kappa–Carrageenan (KCG) was initially degraded to a lower molecular weight KCG (LKCG) by H₂O₂, and was selected as wall material to coat TP. The obtained LKCG (Mn = 13,009.5) revealed narrow dispersed fragments (DPI = 1.14). FTIR and NMR results demonstrated that the main chemical structure of KCG remained unchanged after degradation. Subsequently, LK-CG and TP were mixed and homogenized to form LK-CG-TP microspheres. SEM images of the microspheres revealed a regular spherical shape and smooth surface with a mean diameter of 5–10 μM. TG and DSC analysis indicated that LK-CG-TP microspheres exhibited better thermal stability as compared to free TP. The release profile of LK-CG-TP in simulated gastric fluid (SGF) showed a slowly release capacity during the tested 180 min with the final release rate of 88.1% after digestion. Furthermore, in vitro DPPH radical scavenging experiments revealed that LK-CG-TP had an enhanced DPPH scavenging rate as compared to equal concentration of free TP. These results indicated that LK-CG-TP microspheres were feasible for protection and delivery of TP and might have extensive potential applications in other bioactive components.

中文翻译：

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用于提高茶多酚稳定性和生物利用度的低分子量 Kappa-卡拉胶微球

茶多酚（TP）是一种公认​​的具有生物活性的天然产物，但其稳定性和生物利用度低限制了其在许多领域的应用。为了提高TP在某些温和条件下的稳定性和生物利用度，应用了封装技术。Kappa-卡拉胶 (KCG) 最初被 H ₂ O ₂降解为较低分子量的 KCG (LKCG), 并被选作 TP 涂层的墙体材料。获得的 LKCG (Mn = 13,009.5) 显示出狭窄的分散碎片 (DPI = 1.14)。FTIR和NMR结果表明，降解后KCG的主要化学结构保持不变。随后，将 LK-CG 和 TP 混合均匀，形成 LK-CG-TP 微球。微球的 SEM 图像显示出规则的球形和光滑的表面，平均直径为 5-10 μM。TG和DSC分析表明，与游离TP相比，LK-CG-TP微球表现出更好的热稳定性。LK-CG-TP 在模拟胃液 (SGF) 中的释放曲线显示在测试的 180 分钟内缓慢释放能力，消化后最终释放率为 88.1%。此外，体外 DPPH 自由基清除实验表明，与等浓度的游离 TP 相比，LK-CG-TP 具有增强的 DPPH 清除率。这些结果表明，LK-CG-TP 微球对于 TP 的保护和递送是可行的，并且可能在其他生物活性成分中具有广泛的潜在应用。