稀土镧掺杂纳米ZnO复合保鲜包装薄膜的制备及其性能研究

Composite Films Containing Rare Earth Lanthanum Doped Nano-ZnO as Efficient Materials for Packaging Preservation

制备稀土镧掺杂纳米ZnO(La^(3+)-ZnO)粒子,将其分散于PVA水溶胶中,利用溶液浇铸法制备La^(3+)-ZnO复合保鲜薄膜,并将其应用于草莓和姬松茸的保鲜研究中。XRD、LPSA和TEM表征显示,稀土镧的掺杂引起了纳米ZnO晶格的畸变,其粒径变小,表面能增大,分散性提高。水蒸气透过率和透氧率检测结果表明,当La^(3+)-ZnO的添加质量分数为1.2%时,复合薄膜阻隔性能最佳,与纯PVA薄膜相比,La^(3+)-ZnO复合保鲜薄膜的水蒸气透过率降低了42.7%,透氧率降低了35.6%。抗菌率测试结果显示,稀土镧的掺杂拓宽了纳米ZnO对光谱的利用范围,复合保鲜薄膜在自然光下对大肠杆菌和金黄色葡萄球菌的抗菌率分别达到96.9%和99.3%。保鲜实验结果表明,复合保鲜薄膜可有效抑制草莓贮存过程中的果实腐坏,降低其质量损失,以其包裹的草莓常温下的保质期从5 d延长至10 d左右;同时它可减缓姬松茸贮藏过程中的自溶和褐变等现象,以其包裹的姬松茸常温下的保质期从2d延长至4 d左右。

Lanthanum doped nano-ZnO（La^（3＋）-ZnO） was firstly prepared and dispersed into PVA sol to produce packaging composite films by solution pouring method,and its preservation performances for strawberry and agaricus blazei were investigated.Characterizations of La^（3＋）-ZnO were done by XRD,TEM and LPSA.The distortion occurred in lattice of ZnO with the particle size reduced,surface energy increased and dispersibility improved,all caused by doping with La^（3＋）.Barrier performance of the composite films was improved by adding La^（3＋）-ZnO,and it was revealed that the composite films obtained the optimal barrier performance with mass fraction of La^（3＋）-ZnO being 1.2%.The water vapor permeability and oxygen permeability were decreased by 42.7% and 35.6% respectively.Utilization range of spectrum for ZnO was widened by lanthanum doping,so that the antibacterial rate of the composite films against E.coli.and S.aureus reached 96.9% and 99.3% respectively in natural light.The strawberries were well preserved for 10 d at room temperature with the composite film,while the rotted rate and weight loss rate were both controlled below 5%.The shelf life of agaricus blazei was also extended from 2 d to 5 d at room temperature,since the composite films slowed down the browning,autolysis and other phenomena during the storage of agaricus blazei.