该研究采用高直链玉米淀粉为原料，经盐酸和普鲁兰酶改性后制备得到具有不同链长分布的线性糊精聚集物，并构建二十二碳六烯酸（Docosahexaenoic Acid，DHA）微胶囊，系统研究了链长分布对微胶囊有序结构、包埋效率、氧化稳定性及抗消化性的影响。研究表明，酸解0~96 h后，线性糊精聚集物中长链线性糊精（聚合度大于100）的比例从95.22%减少到65.76%，而短链线性糊精（聚合度10~100）比例由4.62%提高到33.73%。微胶囊的短程有序结构含量随着短链线性糊精占比的增加而提高，说明降低链长有利于线性糊精-DHA络合物与双螺旋结构的形成。随着短链线性糊精含量的增加，微胶囊中V型结晶结构含量从1.18%逐渐增加到8.44%，而B型结晶结构含量则从7.84%降低为2.57%。线性糊精聚集物含有22.17%的短链线性糊精和77.46%的长链线性糊精时，微胶囊表现出最佳的包埋效率、氧化稳定性和抗消化性。结果表明，可通过缩短线性糊精分子链长来促进双螺旋结构和线性糊精-DHA络合物的形成，进而改善DHA微胶囊的性能。

Linear dextrin aggregates comprising different chain length distributions were prepared from high-amylose corn starch modified using hydrochloric acid and pullulanase. Docosahexaenoic acid (DHA) microcapsules were prepared, and the effects of chain length distribution on the ordered structure, encapsulation efficiency, oxidation stability and digestion resistance of the microcapsules were systematically studied. The results showed that the proportion of long-chain linear dextrin (degree of polymerization > 100) in the linear dextrin aggregates decreased from 95.22% to 65.76%, whereas the proportion of short-chain linear dextrin (degree of polymerization: 10~100) increased from 4.62% to 33.73% after 0~96 h of acid hydrolysis. The content of short-range ordered structures in the microcapsules increased with the proportion of short-chain linear dextrin, indicating that reducing the chain length is beneficial to the formation of the linear dextrin-DHA complex and double helix structures. The content of V-type crystal structure in microcapsules gradually increased from 1.18% to 8.44% with the increase in short-chain linear dextrin content, whereas the content of B-type crystal structure decreased from 7.84% to 2.57%. Linear dextrin aggregates that contained 22.17% short-chain linear dextrin and 77.46% long-chain linear dextrin produced microcapsules with the best encapsulation efficiency, oxidation stability, and digestion resistance. The results showed that the formation of the double helix structure and the linear dextrin-DHA complex can be promoted by shortening the molecular chain length of linear dextrin, thereby improving the performance of DHA microcapsules.

国家自然科学基金项目（22178124）；111项目（B17018）；广州市科技计划项目（202102080150）