This study presents an innovative approach to developing biodegradable food packaging by synthesizing a starch-based film with enhanced water resistance and antimicrobial properties. To achieve this, starch (ST) was chemically modified through an additive reaction with N-isopropylacrylamide (NIPA) and subsequently blended with chitosan (CS), improving its hydrophobicity and antimicrobial properties. The structural and chemical interactions within the modified film were characterized using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD), confirming the successful integration of these components. The modification of starch ST with NIPA via a Michael reaction effectively reduced the film’s moisture sensitivity by substituting hydroxyl groups, leading to improved hydrophobicity. This enhancement was reflected in a significant increase in the contact angle from 44.79° for the pure ST film to 77.95° for the ST-37.5% NIPA/CS blend, along with a reduction in water vapor permeability (WVP) from 1.95 × 10^–10 g·cm/(cm²·s·Pa) for the pure ST film to 1.11 × 10^–10 g·cm/(cm²·s·Pa) for the ST-37.5% NIPA/CS film, demonstrating enhanced moisture barrier properties. Additionally, the ST-NIPA/CS film exhibited superior mechanical properties, including a tensile strength (TS) of 11.27 MPa and an elongation at break (EAB) of 185.92%. Notably, the films demonstrated strong antibacterial activity against Escherichia coli and Staphylococcus aureus, with inhibition zone diameters of 7.62 and 10.25 mm, respectively. The ST-NIPA/CS film effectively extended the shelf life of fresh-cut apples, achieving a decay index of 30.5% and a weight loss of 3.11% after 4 days, highlighting its potential as a sustainable packaging material.

中文翻译：

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增强淀粉基食品包装薄膜：N-异丙基拉克酰胺和壳聚糖对疏水性和抗菌性能的协同作用

本研究提出了一种通过合成具有增强耐水性和抗菌性能的淀粉基薄膜来开发可生物降解食品包装的创新方法。为了实现这一目标，通过与 N-异丙基丙酰胺 （NIPA） 的加成反应对淀粉 （ST） 进行化学改性，随后与壳聚糖 （CS） 混合，从而提高其疏水性和抗菌性。使用 X 射线光电子能谱 （XPS）、傅里叶变换红外光谱 （FTIR） 和 X 射线衍射 （XRD） 表征改性薄膜内的结构和化学相互作用，证实了这些组件的成功集成。通过 Michael 反应用 NIPA 对淀粉 ST 进行改性，通过取代羟基，有效地降低了薄膜的湿敏性，从而提高了疏水性。这种增强体现在接触角从纯 ST 薄膜的 44.79° 显着增加到 ST-37.5% NIPA/CS 混合物的 77.95°，同时水蒸气渗透率 （WVP） 从 1.95 降低× 10^–10 g·cm/（cm²·s·Pa） 的 1×0^–10 g·cm/（cm²·s·Pa） 用于 ST-37.5% NIPA/CS 薄膜，表现出增强的防潮性能。此外，ST-NIPA/CS 薄膜表现出优异的机械性能，包括 11.27 MPa 的拉伸强度 （TS） 和 185.92% 的断裂伸长率 （EAB）。值得注意的是，这些薄膜对大肠杆菌和金黄色葡萄球菌表现出很强的抗菌活性，抑制区直径分别为 7.62 和 10.25 mm。 ST-NIPA/CS 薄膜有效延长了鲜切苹果的保质期，4 天后腐烂指数达到 30.5%，重量减轻 3.11%，凸显了其作为可持续包装材料的潜力。