The aim of this investigation was to develop the high moisture protective ability and stable pectin through the design of composite films based on varying shellac concentrations. A film casting method was applied to prepare a free film. The moisture protective properties and mechanical properties were investigated. The findings was the composite films exhibited the reductions in the hydrophilicity, water vapor permeability, and the moisture content compared with pectin films. The single and composite films were then study for their stability at 40 °C and 75% RH for 90 d. Among the concentrations of shellac, 50% (w/w) could improve stability in terms of moisture protection after 90 d of storage, whereas lower concentrations of shellac (10% to 40%) could not achieve this. However, the higher shellac content also contributed to weaker mechanical properties. The mechanical improvement and stability of composite films with the incorporation of plasticizers were further investigated. Polyethylene glycol 400 and diethyl phthalate at a concentration of 10% were used. The results indicated that both plasticizers could enhance the mechanical characteristics and had a slight effect on moisture protection. The stability of pectin in terms of moisture protective properties could, therefore, be modified through the fabrication of composite films with hydrophobic polymers, that is, shellac and the addition of proper plasticizers to enhance mechanical properties, which could offer wide applications for edible film in food, agro, and pharmaceutical industries. PRACTICAL APPLICATION The composite film with 50% shellac could improve moisture protective properties of pectin film. Adding a plasticizer could build up the higher mechanical characteristics of composite film. Stability of pectin could be modified by fabrication of composite films with proper content of shellac and plasticizer.

中文翻译：

---

通过复合膜的形成提高果胶的防潮性能和稳定性：虫胶和增塑剂的作用

本研究的目的是通过设计基于不同虫胶浓度的复合膜来开发高防潮能力和稳定的果胶。应用薄膜流延法制备游离薄膜。研究了防潮性能和机械性能。结果表明，与果胶薄膜相比，复合薄膜的亲水性、水蒸气渗透性和水分含量均有所降低。然后研究单层和复合薄膜在 40 °C 和 75% RH 下 90 天的稳定性。在紫胶浓度中，50% (w/w) 可以提高储存 90 天后防潮的稳定性，而较低浓度的紫胶 (10% 至 40%) 则无法实现这一点。然而，较高的虫胶含量也导致较弱的机械性能。进一步研究了添加增塑剂后复合薄膜的机械性能和稳定性。使用浓度为 10% 的聚乙二醇 400 和邻苯二甲酸二乙酯。结果表明，这两种增塑剂均能增强机械性能，但对防潮性能有轻微影响。因此，果胶在防潮性能方面的稳定性可以通过制备具有疏水性聚合物（即虫胶）的复合薄膜和添加适当的增塑剂来提高机械性能来改变，这可以为可食用薄膜提供广泛的应用。食品、农业和制药行业。实际应用 50%虫胶复合薄膜可提高果胶薄膜的防潮性能。添加增塑剂可以提高复合薄膜的机械性能。通过制备适当含量的虫胶和增塑剂的复合膜可以改善果胶的稳定性。