Liu LinShu, Liu Cheng-Kung, Fishman Marshall L, Hicks Kevin B
Crop Conversion Science and Engineering Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
J Agric Food Chem. 2007 Mar 21;55(6):2349-55. doi: 10.1021/jf062612u. Epub 2007 Feb 21.
Composite films were prepared from pectin and fish skin gelatin (FSG) or pectin and soybean flour protein (SFP). The inclusion of protein promoted molecular interactions, resulting in a well-organized homogeneous structure, as revealed by scanning electron microscopy and fracture-acoustic emission analysis. The resultant composite films showed an increase in stiffness and strength and a decrease in water solubility and water vapor transmission rate, in comparison with films cast from pectin alone. The composite films inherited the elastic nature of proteins, thus being more flexible than the pure pectin films. Treating the composite films with glutaraldehyde/methanol induced chemical cross-linking with the proteins and reduced the interstitial spaces among the macromolecules and, consequently, improved their mechanical properties and water resistance. Treating the protein-free pectin films with glutaraldehyde/methanol also improved the Young's modulus and tensile strength, but showed little effect on the water resistance, because the treatment caused only dehydration of the pectin films and the dehydration is reversible. The composite films were biodegradable and possessed moderate mechanical properties and a low water vapor transmission rate. Therefore, the films are considered to have potential applications as packaging or coating materials for food or drug industries.
复合薄膜由果胶与鱼皮明胶（FSG）或果胶与大豆粉蛋白（SFP）制备而成。扫描电子显微镜和断裂声发射分析表明，蛋白质的加入促进了分子间相互作用，形成了结构良好的均匀结构。与仅由果胶浇铸而成的薄膜相比，所得复合薄膜的硬度和强度增加，水溶性和水蒸气透过率降低。复合薄膜继承了蛋白质的弹性本质，因此比纯果胶薄膜更具柔韧性。用戊二醛/甲醇处理复合薄膜会与蛋白质发生化学交联，减少大分子之间的间隙，从而改善其机械性能和耐水性。用戊二醛/甲醇处理不含蛋白质的果胶薄膜也能提高杨氏模量和拉伸强度，但对耐水性影响不大，因为该处理仅导致果胶薄膜脱水，且脱水是可逆的。复合薄膜可生物降解，具有适度的机械性能和较低的水蒸气透过率。因此，这些薄膜被认为具有作为食品或制药行业包装或涂层材料的潜在应用。
