Data_Sheet_4_Preparation of Natural Food-Grade Core-Shell Starch/Zein Microparticles by Antisolvent Exchange and Transglutaminase Crosslinking for Reduced Digestion of Starch.xlsx

The purpose of this study was to slow down the digestibility of starch granules by encapsulating it in zein shells. Drop of the preformed swollen corn starch (CS) granule suspension into thermal-treated zein ethanolic solution enables antisolvent precipitation of thermal-treated zein on the surface of the preformed swollen CS granules, leading to the formation of core-shell starch/zein microparticles. Confocal laser scanning microscopy images showed that the preformed swollen CS granules were coated by thermal-treated zein shells with a thickness of 0.48–0.95 μm. The volume average particle diameter of core-shell starch/zein microparticles was 14.70 μm and reached 18.59–30.98 μm after crosslinking by transglutaminase. The results of X-ray diffraction and Fourier transform infrared spectroscopy demonstrated that an interaction occurred between the preformed swollen CS granules and the thermal-treated zein. The results for thermodynamic characteristics, pasting properties, and swelling power indicated that the compact network structure of core-shell starch/zein microparticles crosslinked by transglutaminase could improve starch granule thermal stability and resistance to shearing forces. Compared to native CS, the peak gelatinization temperatures of core-shell starch/zein microparticles increased significantly (p < 0.05), with a maximum value of 76.64°C. The breakdown values and the swelling power at 95°C of core-shell starch/zein microparticles significantly (p < 0.05) decreased by 52.83–85.66% and 0.11–0.28%, respectively. The in vitro digestibility test showed that the contents of slowly digestible starch and resistant starch in the core-shell starch/zein microparticles increased to ∼42.66 and ∼34.75%, respectively, compared to those of native CS (9.56 and 2.48%, respectively). Our research supports the application of food-grade core-shell starch/zein microparticles to formulate low-digestibility food products.

本研究旨在通过将玉米淀粉颗粒包裹于玉米醇溶蛋白（zein）外壳中，延缓其消化速率。将预先制备的溶胀玉米淀粉（corn starch, CS）颗粒悬浮液滴加入经热处理的玉米醇溶蛋白乙醇溶液中，可使经热处理的玉米醇溶蛋白在预溶胀玉米淀粉颗粒表面发生反溶剂沉淀，进而形成核壳型淀粉/玉米醇溶蛋白微球。共聚焦激光扫描显微镜（confocal laser scanning microscopy）成像结果显示，预溶胀玉米淀粉颗粒被厚度为0.48–0.95 μm的热处理玉米醇溶蛋白外壳所包覆。核壳型淀粉/玉米醇溶蛋白微球的体积平均粒径为14.70 μm，经谷氨酰胺转氨酶（transglutaminase）交联后，粒径可达18.59–30.98 μm。X射线衍射（X-ray diffraction）与傅里叶变换红外光谱（Fourier transform infrared spectroscopy）检测结果表明，预溶胀玉米淀粉颗粒与热处理玉米醇溶蛋白之间存在相互作用。热力学特性、糊化特性与膨胀力的分析结果显示，经谷氨酰胺转氨酶交联的核壳型淀粉/玉米醇溶蛋白微球所形成的致密网络结构，可提升淀粉颗粒的热稳定性与抗剪切性能。与天然玉米淀粉相比，该微球的峰值糊化温度显著升高（p < 0.05），最高可达76.64℃。其崩解值与95℃下的膨胀力分别显著降低52.83%–85.66%与0.11%–0.28%（p < 0.05）。体外消化实验结果表明，相较于天然玉米淀粉的慢消化淀粉与抗性淀粉含量（分别为9.56%与2.48%），核壳型淀粉/玉米醇溶蛋白微球的慢消化淀粉与抗性淀粉含量分别提升至约42.66%与约34.75%。本研究证实了食品级核壳型淀粉/玉米醇溶蛋白微球在制备低消化率食品中的应用价值。