Abstract This study aimed to design mixed hydrogels composed of whey protein aggregates (WPA)/k-carrageenan with a tailored microstructure to protect curcumin within the upper gastrointestinal tract and deliver it to the colon. Curcumin was loaded in WPA and followed by cold gelation of the aggregates in the presence of k-carrageenan. The Microstructure of the hydrogels varied from homogenous to protein continuous or k-carrageenan continuous depending on the k-carrageenan concentration (0.0, 0.1 and 0.55%, w/w). The physical stability of curcumin toward precipitation during gelation of curcumin-loaded WPA was significantly improved after k-carrageenan addition. The higher capacity of k-carrageenan containing gels to curcumin entrapment was attributed to curcumin embedment inside of the rich-protein microdomains (called microgels), higher viscosity of the gel pre-solutions contained k-carrageenan and the shorter gelation time of the corresponding gels. Moreover, it was found about 31% of the loaded curcumin was released in the simulated gastrointestinal tract for pure WPA gels, while after addition of 0.55% k-carrageenan to WPA gels, more than 87% of loaded curcumin were delivered to the colon. Besides, 33% of curcumin degraded after the gastrointestinal digestion, while for WPA gels containing 0.1% and 0.55% k-carrageenan it was only 9.6% and 3.5%, respectively. The results were attributed to the protective effect of k-carrageenan to protein during in vitro digestion so that the access of digestive enzymes into the hydrogels was limited resulting in a reduction of gel matrix erosion and curcumin release. Therefore, curcumin remained bound to the protein and was not damaged during digestion until it reaches the colon.

中文翻译：

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加载姜黄素的乳清蛋白聚集体与 k-卡拉胶混合的冷凝胶化：凝胶微结构对姜黄素胃肠道归宿的影响

摘要 本研究旨在设计由乳清蛋白聚集体 (WPA)/k-卡拉胶组成的混合水凝胶，具有定制的微观结构，以保护上消化道内的姜黄素并将其输送到结肠。姜黄素加入 WPA 中，然后在 k-角叉菜胶存在下使聚集体冷凝胶化。水凝胶的微观结构从均质到蛋白质连续或 k-卡拉胶连续变化，这取决于 k-卡拉胶浓度（0.0、0.1 和 0.55%，w/w）。添加k-角叉菜胶后，姜黄素在负载姜黄素的WPA凝胶过程中对沉淀的物理稳定性显着提高。含有 k-角叉菜胶的凝胶对姜黄素的捕获能力较高归因于姜黄素嵌入富含蛋白质的微区（称为微凝胶）内，含有 k-角叉菜胶的凝胶预溶液粘度越高，相应凝胶的胶凝时间越短。此外，发现大约 31% 的负载姜黄素在纯 WPA 凝胶的模拟胃肠道中释放，而在 WPA 凝胶中添加 0.55% 的 k-角叉菜胶后，超过 87% 的负载姜黄素被输送到结肠。此外，33% 的姜黄素在胃肠消化后降解，而对于含有 0.1% 和 0.55% k-卡拉胶的 WPA 凝胶，分别仅为 9.6% 和 3.5%。结果归因于 k-卡拉胶在体外消化过程中对蛋白质的保护作用，从而限制了消化酶进入水凝胶的途径，从而减少了凝胶基质侵蚀和姜黄素释放。所以，