Key Laboratory of Science and Technology of Eco-Textile, Ministry of Education, Jiangnan University, 1800 Lihu Ave., Wuxi 214122, Jiangsu, China.
Key Laboratory of Science and Technology of Eco-Textile, Ministry of Education, Jiangnan University, 1800 Lihu Ave., Wuxi 214122, Jiangsu, China..
Int J Biol Macromol. 2019 Oct 1;138:736-743. doi: 10.1016/j.ijbiomac.2019.07.118. Epub 2019 Jul 21.
Starch retrogradation is an inevitable process in the natural state caused by motion of starch molecular chains. However, traditional starch retrogradation research methods cannot explain this process from the aspect of chain motion. Therefore, the objective of this study was to investigate the effect of pullulan (PUL) on potato starch (PS) retrogradation and analyze this using condensed matter theory. The entanglement concentration (c) was determined by Ubbelohde viscometer. The c values of PS and PS-PUL were 0.22 and 0.32 g/dL, respectively. Small-angle X-ray Scattering (SAXS) was used to obtain the radius of gyration (R) values and investigate conformation evolution of PS and PS-PUL in different solution concentrations ranging from extremely dilute to concentrated. The R values of PS increased by 38.7% upon transition from single chain (0.001 g/dL) to an entanglement state (0.22 g/dL) and the percent reduction of R was only 3.3% from entanglement state (0.22 g/dL) to stabilization (1 g/dL). The percent increase of R values of PS-PUL reached to 34.7% from extremely dilute (0.001 g/dL) to concentrated (1 g/dL) solutions. The trend of R indicated that c played a major role in starch retrogradation. Dynamic light scattering (DLS) was used to acquire the hydrodynamic radius (R) which was a significant parameter to calculate form factor (ρ) by the ratio: ρ = R/R. The ρ values of PS-PUL were generally lower than those for PS. This result illustrated that PUL delayed the process of starch retrogradation by increasing flexibility of PS molecular chain. Furthermore, the ρ value of PS-PUL was higher than PS at 0.22 g/dL (c of PS). This result illustrated that entanglement could decreased flexibility of molecular chain. The present research provides a novel research route for exploring the influence of hydrocolloids on starch retrogradation from the viewpoint of chain motion.
淀粉回生是淀粉分子链运动引起的自然状态下不可避免的过程。然而，传统的淀粉回生研究方法无法从链运动的角度解释这一过程。因此，本研究旨在探讨普鲁兰（PUL）对马铃薯淀粉（PS）回生的影响，并利用凝聚态理论对其进行分析。用乌贝洛德粘度计测定缠结浓度（c）。PS 和 PS-PUL 的 c 值分别为 0.22 和 0.32 g/dL。小角 X 射线散射（SAXS）用于获得旋转半径（R）值，并研究 PS 和 PS-PUL 在从极度稀溶液到浓溶液的不同溶液浓度下的构象演变。PS 从单链（0.001 g/dL）到缠结状态（0.22 g/dL）的转变，R 值增加了 38.7%，而从缠结状态（0.22 g/dL）到稳定状态（1 g/dL），R 值的降低仅为 3.3%。PS-PUL 的 R 值从极度稀溶液（0.001 g/dL）增加到浓溶液（1 g/dL）时，增加了 34.7%。R 值的趋势表明，c 在淀粉回生中起主要作用。动态光散射（DLS）用于获得流体力学半径（R），通过比值计算形态因子（ρ）：ρ=R/R。PS-PUL 的 ρ 值通常低于 PS。这一结果表明，PUL 通过增加 PS 分子链的柔韧性来延缓淀粉回生过程。此外，PS-PUL 的 ρ 值在 0.22 g/dL（PS 的 c 值）时高于 PS。这一结果表明，缠结可以降低分子链的柔韧性。本研究为从链运动的角度探索水胶体对淀粉回生的影响提供了一条新的研究途径。
