Hernandez-Izquierdo V M, Krochta J M
Dept. of Biological and Agricultural Engineering, Univ. of California, Davis, Davis, CA 95616, USA.
J Food Sci. 2008 Mar;73(2):R30-9. doi: 10.1111/j.1750-3841.2007.00636.x.
Increasing interest in high-quality food products with increased shelf life and reduced environmental impact has encouraged the study and development of edible and/or biodegradable polymer films and coatings. Edible films provide the opportunity to effectively control mass transfer among different components in a food or between the food and its surrounding environment. The diversity of proteins that results from an almost limitless number of side-chain amino-acid sequential arrangements allows for a wide range of interactions and chemical reactions to take place as proteins denature and cross-link during heat processing. Proteins such as wheat gluten, corn zein, soy protein, myofibrillar proteins, and whey proteins have been successfully formed into films using thermoplastic processes such as compression molding and extrusion. Thermoplastic processing can result in a highly efficient manufacturing method with commercial potential for large-scale production of edible films due to the low moisture levels, high temperatures, and short times used. Addition of water, glycerol, sorbitol, sucrose, and other plasticizers allows the proteins to undergo the glass transition and facilitates deformation and processability without thermal degradation. Target film variables, important in predicting biopackage performance under various conditions, include mechanical, thermal, barrier, and microstructural properties. Comparisons of film properties should be made with care since results depend on parameters such as film-forming materials, film formulation, fabrication method, operating conditions, testing equipment, and testing conditions. Film applications include their use as wraps, pouches, bags, casings, and sachets to protect foods, reduce waste, and improve package recyclability.
对具有更长保质期和更低环境影响的高品质食品的兴趣日益浓厚，这推动了可食用和/或可生物降解聚合物薄膜及涂层的研究与开发。可食用薄膜为有效控制食品中不同成分之间或食品与其周围环境之间的质量传递提供了机会。由于侧链氨基酸序列排列几乎无限，蛋白质具有多样性，这使得在热加工过程中蛋白质变性和交联时会发生广泛的相互作用和化学反应。诸如小麦面筋、玉米醇溶蛋白、大豆蛋白、肌原纤维蛋白和乳清蛋白等蛋白质已通过热塑性加工工艺（如压缩成型和挤出）成功制成薄膜。由于热塑性加工使用的水分含量低、温度高且时间短，因此可形成一种具有商业潜力的高效制造方法，用于大规模生产可食用薄膜。添加水、甘油、山梨醇、蔗糖和其他增塑剂可使蛋白质发生玻璃化转变，并在不发生热降解的情况下促进变形和加工性能。在预测各种条件下生物包装性能时很重要的目标薄膜变量包括机械性能、热性能、阻隔性能和微观结构性能。由于结果取决于诸如成膜材料、薄膜配方、制造方法、操作条件、测试设备和测试条件等参数，因此在比较薄膜性能时应谨慎。薄膜应用包括用作包装纸、小袋、袋子、肠衣和香囊，以保护食品、减少浪费并提高包装的可回收性。
