Our study focused on the preparation and characterization of biocomposite films consisting of poly(vinyl alcohol) (PVA) and green tea extract (GTE) with a small amount of glycerol as a plasticizer. Scanning electron microscopy (SEM) showed that both the surface and cross-section of the GTE-PVA biocomposite films were smooth and uniform. Incorporation of GTE could considerably alter the optical and mechanical properties of the pure PVA film. Notably, the GTE-PVA biocomposite films presented better water vapor and UV–vis light barrier properties and higher mechanical strength than the pure PVA film. The antioxidant ability of the biocomposite films was evaluated by measuring the 2,2-diphenyl-1-picrylhydrazyl radical scavenging and ferric reducing power in terms of the total phenolic content. The GTE-PVA biocomposite films showed higher antioxidant activity than the pure PVA film, and the antioxidant activity increased with increasing GTE concentration. The color of the GTE-PVA biocomposite films became yellow when the pH was lower than 6 and became dark red when the pH was higher than 6. Moreover, color variations were observed in the GTE-PVA biocomposite films by changing the pH. These results suggest that GTE-PVA composite films may be used as a promising antioxidant and visible pH-sensing food packaging materials.

我们的研究重点在于由聚乙烯醇（PVA）和绿茶提取物（GTE）以及少量甘油作为增塑剂的生物复合膜的制备和表征。扫描电子显微镜（SEM）显示，GTE-PVA生物复合膜的表面和横截面均光滑且均匀。掺入GTE可能会大大改变纯PVA薄膜的光学和机械性能。值得注意的是，与纯PVA膜相比，GTE-PVA生物复合膜具有更好的水蒸气和紫外线可见光阻隔性能，以及更高的机械强度。通过根据总酚含量测量2，2-二苯基-1-吡啶并肼基自由基清除能力和三价铁还原能力来评估生物复合膜的抗氧化能力。GTE-PVA生物复合膜比纯PVA膜具有更高的抗氧化活性，且抗氧化活性随GTE浓度的增加而增加。当pH低于6时，GTE-PVA生物复合膜的颜色变为黄色，而当pH高于6时，其变为深红色。此外，通过改变pH，在GTE-PVA生物复合膜中观察到颜色变化。这些结果表明，GTE-PVA复合膜可用作有希望的抗氧化剂和可见的pH敏感食品包装材料。通过改变pH值，在GTE-PVA生物复合膜中观察到颜色变化。这些结果表明，GTE-PVA复合膜可用作有希望的抗氧化剂和可见的pH敏感食品包装材料。通过改变pH值，在GTE-PVA生物复合膜中观察到颜色变化。这些结果表明，GTE-PVA复合膜可用作有希望的抗氧化剂和可见的pH敏感食品包装材料。