糖接枝玉米醇溶蛋白包埋虾青素

本研究利用葡萄糖和木糖两种还原糖对玉米醇溶蛋白（zein）进行糖接枝改性，并制备改性zein/虾青素复合 微粒，研究糖接枝改性对包埋虾青素的影响。zein-葡萄糖/木糖的接糖量分别为2.59%和2.53%，十二烷基硫酸钠-聚 丙烯酰胺凝胶电泳后的考马斯亮蓝染色和希夫试剂染色结果也充分证明了糖蛋白的产生。圆二色谱测定结果表明， 经过糖接枝改性后的zein二级结构中α-螺旋结构含量显著减少，而β-折叠和β-转角结构含量增加，说明蛋白质发生 了一定程度的展开。扫描电子显微镜和差示扫描量热结果表明，虾青素经过zein包埋后形成的复合微粒为空心塌 陷的微粒，虾青素均匀分布在球体中。糖接枝改性后的zein对虾青素包埋率提高了10%。在无水乙醇体系下溶解 12 h，未包埋的虾青素释放率达99.8%，zein/虾青素、zein-葡萄糖/虾青素、zein-木糖/虾青素复合微粒中虾青素释放 率分别为49.7%、31.7%、30.2%。经过糖接枝改性的复合微粒显著提高了虾青素的热稳定性，在热处理过程中，未 被包埋的虾青素破坏率达75.29%，而经过包埋的虾青素破坏率均在25%以下。

Encapsulation of Astaxanthin in Zein-Saccharide Graft Reaction Products

In this study, zein was grafted with glucose or xylose, and grafted zein/astaxanthin particles were prepared to study the impact of glycosylation on the encapsulation of astaxanthin. The percentages of glucose and xylose grafted onto zein were 2.59% and 2.53%, respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) using Coomassie staining and Schiff staining proved the existence of glycoprotein. Circular dichroism results showed that the secondary structure of zein was changed as evidenced by a decrease of alpha-helix and an increase of beta-sheet and beta-turn, indicating partial protein unfolding. The field emission scanning electron microscopy and differential scanning calorimetry measurements showed that the formed zein/astaxanthin particles were hollow with astaxanthin well dispersed around. Compared to the untreated zein, the encapsulation efficiency of astaxanthin was increased by 10% in the grafted zein. After dissolving in ethanol solution for 12 h, the release rate of pure astaxanthin was 99.8%, while in the case of zein/astaxanthin, zein-glucose/astaxanthin, zein-xylose/astaxanthin particles, the release rates were 49.7%, 31.7% and 30.2%, respectively. The thermal stability of astaxanthin was significantly improved in these particles. After heating treatment, the loss rate of pure astaxanthin was 75.29%, while only 25% of encapsulated astaxanthin was lost.