富含苹果皮根皮素壳聚糖-聚乙烯醇抗氧化保鲜膜的研制

壳聚糖-PVA复合膜在食品包装领域具有可降解、抑菌、成膜性好的应用优势，但存在阻隔性能差、机械强度低、抑菌性低、热稳定性差等缺点.基于对壳聚糖-PVA复合膜性能上进行改进，将天然抗氧化成分根皮素加入其中，通过溶液复合法制备不同浓度(质量分数0%、1%、2%和3%) 富含苹果皮提取物根皮素的壳聚糖-PVA复合膜，测定其机械性质与水蒸气透过率，并对其结构进行表征.根皮素的加入增加了壳聚糖-PVA复合膜的热稳定性、拉伸强度和水蒸气透过率，降低了其断裂伸长率.用扫描电子显微镜(SEM)进一步研究了薄膜的表面和截面.此外，红外光谱(FT-IR)测试显示，在薄膜基体中形成了氢键.X-射线衍射(XRD)分析表明，根皮素的添加对壳聚糖-PVA膜的无定形性没有影响.与对照相比，富含根皮素的壳聚糖-PVA膜的抗氧化活性(ABTS和DPPH自由基清除能力和还原能力)和抗菌能力均有所提高.上述结果表明，根皮素是一种优良的添加剂，有助于壳聚糖-PVA膜的性能提高，在食品包装薄膜开发方面具有潜在应有价值.

Preparation of chitosan-PVA composite membranes containing phloretin and used as antioxidant film

Chitosan-PVA composite film was widely applied in food packing due to biodegradability， bacteriostasis and excellent film-forming， but in the meantime， the inherent drawbacks such as poor barrier performance， low mechanical strength， low bacteriostasis and poor thermal stability limited the packing performance. In this paper， phloretin， a natural antioxidant， was used to modify the packing performance of chitosan-PVA composite film. Chitosan-PVA composite films with different concentration (0%， 1%， 2% and 3%， m/V) of phloretin were prepared by solution compounding method. The mechanical properties， water vapor transmission and structure were characterized in detail. The results show that the thermal stability， tensile strength and water vapor transmission of chitosan PVA composite membrane were obviously increased with the dosage increase of phloretin； in contrast， the break extension was decreased. The surface and cross section of the films were further studied by scanning electron microscopy (SEM). The FT-IR result showed that hydrogen bonds were formed in the film substrate. The XRD analysis exhibited that the phloretin has no effect on the amorphous property of chitosan-PVA composite film. The antioxidant activity (ABTS and DPPH radical scavenging ability and reducing ability) and antibacterial activity of chitosan-PVA composite films were significantly improved after adding phloretin. The research indicated that phloretin is an excellent additive， which would improve the properties of chitosan-PVA composite film and has potential value in the development of food packaging film.