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大豆种皮纳米纤维素复合膜的制备、表征及其对冷鲜鸡肉的保鲜作用

Preparation and characterization of soy hull nanocellulose composite film and its preservation for cold fresh chicken

  • 摘要: 为提高大豆副产物的综合利用价值并探讨其在食品保鲜中的应用潜力,该研究采用超声辅助酸解法制备大豆种皮纳米纤维素(soy hull nanocellulose,SHNC),并以大豆种皮纳米纤维素、聚乙烯醇(polyvinyl alcohol,PVA)和普鲁兰多糖(pullulan, PUL)为原料,采用溶液浇筑成膜法制备PVA/PUL/SHNC复合膜。对复合膜的厚度、力学性能、热稳定性、接触角、水分含量、水蒸气透过率等理化指标和复合膜的结构进行表征。结果表明,SHNC与PVA、PUL之间存在较强的氢键作用。SHNC使复合膜的拉伸强度和断裂伸长率分别提高了67.1%和100.7%。同时,复合膜热稳定性、疏水性能、贮藏稳定性和水蒸气阻隔性能也明显增强。抑菌试验表明PVA/PUL/SHNC-3复合膜具有抑制大肠杆菌生长的作用,保鲜试验验证了PVA/PUL/SHNC-3复合膜能有效地减缓冷鲜鸡肉中菌落总数的增长、挥发性盐基氮(total volatile base nitrogen, TVB-N)含量和pH值的上升,保持冷鲜鸡肉新鲜度并显著地延长货架期(P<0.05)。PVA/PUL/SHNC复合膜为开发冷鲜肉保鲜贮藏新方法提供了一定的参考。

     

    Abstract: With its high aspect ratio and renewable characteristics, nanocellulose not only exhibits excellent biodegradability, but also forms hydrogen bonds between abundant hydroxyl groups (-OH) on the surface and group materials when used as a reinforcing filler. It can also significantly enhance the mechanical properties and thermal stability of the composites. In this work, soy hull nanocellulose (SHNC) was prepared by ultrasonic-assisted acid hydrolysis, and PVA/PUL/SHNC composite film were prepared by solution casting method using soy hull nanocellulose, polyvinyl alcohol (PVA) and pullulan (PUL) as raw materials. The chemical structure of the composite film was characterized by Fourier transform infrared spectroscopy (FT-IR), and the changes of the vibration peaks of the characteristic functional groups were analyzed to verify the molecular interaction and chemical compatibility between the components. The crystallinity of the composite film was tested by X-ray diffractometer (XRD), and the microscopic morphology of the composite film was observed by scanning electron microscope (SEM), including key morphological parameters such as surface uniformity, phase separation phenomenon and cross-sectional layered structure. In terms of thermal stability evaluation. The thermogravimetric analyzer (TGA) was used to test the temperature programmed test of the material. The thickness, mechanical properties, contact angle, water content, water vapor permeability, storage stability and bacteriostatic effect on Escherichia coli of the composite film were tested. Finally, the composite film was applied to the preservation of chilled chicken at 4 ℃ to verify the preservation effect of the composite film on chilled chicken. The results of FT-IR and XRD showed that there was a strong hydrogen bond between SHNC and PVA, PUL, and no crystal was formed. SEM analysis showed that there was a good compatibility between SHNC and the composite film components. The surface and cross section showed a dense structure, and no phase separation or structural defects, such as rupture and holes, were observed. At the same time, SHNC increased the tensile strength and elongation at break of the composite film by 67.1% and 100.7%, respectively, indicating that SHNC had a significant enhancement effect on the mechanical properties of the composite film (P<0.05). TGA test results showed that the maximum thermal degradation temperature of PVA/PUL/SHNC-3 composite film containing SHNC was 317.58 ℃, which was significantly higher than that of PVA/PUL/SHNC-0 (302.41℃) (P<0.05). This is due to the formation of intermolecular hydrogen bonds between SHNC and PVA, PUL to stabilize the structure of the composite film. In addition, SHNC also significantly improved the hydrophobicity of the composite film (P<0.05). The water contact angle experiment showed that SHNC increased the water contact angle of the composite film from 38.8° to 66.4°, confirming the significant optimization of its hydrophobicity (P<0.05). Similarly, SHNC was uniformly dispersed in the composite film, creating a curved channel for the movement of water, which could effectively hinder the migration of water. Therefore, the water vapor permeability of the composite film was reduced from 0.408 8 (g·mm)/(m2·h·kpa) without SHNC to 0.271 5 (g·mm)/(m2·h·kpa), showing excellent water vapor barrier properties. Bacteriostatic experiments showed that the minimum inhibitory concentration of PVA/PUL/SHNC composite film against Escherichia coli was 3 % SHNC. Moreover, the preservation experiment showed that the PVA/PUL/SHNC-3 composite film separated cold fresh chicken from the outside world through its excellent barrier properties, effectively prevented the raw contact with bacteria in the air and slowed down the protein and lipid oxidation of cold fresh chicken, effectively slowed down the growth of the total number of colonies in cold fresh chicken, the increase of TVB-N value and pH value, maintained the freshness of cold fresh chicken and significantly prolonged the shelf life (P < 0.05). Therefore, the composite film prepared by blending SHNC with PVA and PUL has the potential to be developed as a packaging material for cold fresh chicken, and provides a reference for the development of new methods for the preservation and storage of cold fresh meat.

     

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