Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China.
Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China.
Ultrason Sonochem. 2024 Jun;106:106891. doi: 10.1016/j.ultsonch.2024.106891. Epub 2024 Apr 29.
Microalgae are new and sustainable sources of starch with higher productivity and flexible production modes than conventional terrestrial crops, but the downstream processes need further development. Here, ultrasonication (with power of 200 W or 300 W and duration of 10, 15, 20, or 25 min) was applied to simultaneously extract and modify starch from a marine microalga Tetraselmis subcordiformis for reducing the digestibility, and an aqueous two-phase system (ATPS) of ethanol/NaHPO was then used to isolate the starches with varied properties. Increasing ultrasonic duration facilitated the partition of starch into the bottom pellet, while enhancing the ultrasonic power was conducive to the allocation in the interphase of the ATPS. The overall starch recovery yield reached 73 ∼ 87 % and showed no significant difference among the ultrasonic conditions tested. The sequential ultrasonication-ATPS process successfully enriched the starch with purities up to 65 % ∼ 88 %, which was among the top levels reported in microalgal starch isolated. Ultrasonication produced more amylose which was mainly fractionated into the interface of the ATPS. The digestibility of the starch was altered under different ultrasonic conditions and varied from different ATPS phases as well, with the one under the ultrasonic power of 200 W for 15 min at the bottom pellet having the highest resistant starch content (RS, 39.7 %). The structural and compositional analysis evidenced that the ultrasonication-ATPS process could exert impacts on the digestibility through altering the surface roughness and fissures of the starch granules, modulating the impurity compositions (protein and lipid) that could interact with starch, and modifying the long- and short-range ordered structures. The developed ultrasonication-ATPS process provided novel insights into the mechanism and strategy for efficient production of functional starch from microalgae with a potential in industrial application.
微藻是新型可持续的淀粉来源，其生产力比传统陆生作物更高，生产方式更灵活，但下游加工仍需进一步开发。本文采用超声（功率为 200 W 或 300 W，持续时间为 10、15、20 或 25 min）同时从海洋微藻塔胞藻中提取和修饰淀粉，以降低其消化率，然后使用乙醇/NaHPO4 的双水相系统（ATPS）分离具有不同性质的淀粉。增加超声持续时间有利于淀粉分配到底部颗粒中，而提高超声功率则有利于分配到 ATPS 的相间。总淀粉回收率达到 73%∼87%，在测试的超声条件之间没有显著差异。顺序超声-ATPS 工艺成功地将淀粉富集到纯度高达 65%∼88%的程度，这在微藻淀粉分离中处于较高水平。超声处理产生了更多的直链淀粉，主要分配到 ATPS 的界面。在不同的超声条件下，淀粉的消化率也发生了变化，并且在不同的 ATPS 相中也有所不同，在功率为 200 W、持续时间为 15 min 的条件下，淀粉在底部颗粒中的抗性淀粉含量（RS）最高（39.7%）。结构和组成分析表明，超声-ATPS 工艺可以通过改变淀粉颗粒的表面粗糙度和裂缝，调节与淀粉相互作用的杂质成分（蛋白质和脂质），以及修饰长程和短程有序结构，来影响淀粉的消化率。该超声-ATPS 工艺为从微藻中高效生产功能性淀粉提供了新的见解，有望在工业应用中得到应用。
