College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China.
College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China.
Int J Biol Macromol. 2018 Jul 15;114:1086-1093. doi: 10.1016/j.ijbiomac.2018.04.021. Epub 2018 Apr 6.
In this study, chitosan (CS) was degraded by ascorbate radical (Asc) and hydroxyl radical (OH), respectively. The structural, physicochemical, antioxidant and film forming properties of Asc and OH degraded CS were compared for the first time. Results showed the structure and physicochemical property of Asc degraded CS were significantly different from those of CS. Asc had a deamination effect on CS with the formation of several unsaturated bonds. Accordingly, Asc degraded CS showed decreased crystallinity and thermal stability as well as a planar morphology. By contrast, OH degraded CS showed similar structure, crystallinity and thermal stability to CS. However, OH had an erosion effect on CS with the formation of many cavities inside. Antioxidant assay further demonstrated that the in vitro antioxidant activity of CS was improved by Asc and OH degradations. Moreover, film forming property of CS was also altered by Asc and OH degradations. Asc and OH degraded CS films showed higher thicknesses, UV-vis light barrier property and water vapor permeability than CS film. Besides, Asc degraded CS film had better mechanical properties than CS and OH degraded CS films. Therefore, Asc degradation could be a useful approach to improve the antioxidant and film forming properties of CS.
在这项研究中，壳聚糖（CS）分别被抗坏血酸自由基（Asc）和羟自由基（OH）降解。首次比较了 Asc 和 OH 降解的 CS 的结构、物理化学、抗氧化和成膜性能。结果表明，Asc 降解的 CS 的结构和物理化学性质与 CS 有显著差异。Asc 对 CS 具有脱氨作用，形成了几个不饱和键。因此，Asc 降解的 CS 表现出结晶度和热稳定性降低以及平面形态。相比之下，OH 降解的 CS 与 CS 具有相似的结构、结晶度和热稳定性。然而，OH 对 CS 具有侵蚀作用，形成了许多内部空腔。抗氧化测定进一步表明，CS 的体外抗氧化活性通过 Asc 和 OH 降解得到提高。此外，CS 的成膜性能也通过 Asc 和 OH 降解发生了改变。与 CS 膜相比，Asc 和 OH 降解的 CS 膜具有更高的厚度、紫外可见光阻隔性能和水蒸气透过率。此外，与 CS 和 OH 降解的 CS 膜相比，Asc 降解的 CS 膜具有更好的机械性能。因此，Asc 降解可能是一种有用的方法来提高 CS 的抗氧化和成膜性能。
