紫薯提取物复合微胶囊结合纳米银指示膜对冷鲜羊肉新鲜度的影响

Development of Composite Microcapsule Combined with Nano-silver Indicator Film and Its Application in Monitoring Freshness of Chilled Mutton

摘要:

为研制一种既对pH值敏感又能抑菌的指示膜用于冷鲜羊肉新鲜度监测，制备了紫薯提取物微胶囊（Purple sweet potato extract microcapsules，PEM），以海藻酸钠和低酰基结冷胶（Sodium alginate/low-acyl gellan gum，SAL）为基材，纳米银（Silver nanopaticles，Ag NPs）和微胶囊为增强剂，探究对指示膜（SAL、SAL/Ag NPs、SAL/Ag NPs/PEM）的性能影响，并应用于羊肉新鲜度监测。结果表明，PEM壁材封装效果良好，使芯材热稳定性增强，具有一定抗氧化能力。Ag NPs和PEM的加入提升了单一SAL膜的机械性能、阻隔性能、热稳定性和抗氧化能力；SAL/Ag NPs/PEM2抗拉伸强度（12.21MPa）最高，氧气透过率（7.25g·mm/(m2·d)）最低，横截面紧实整齐；X射线衍射图谱表明，Ag NPS结晶度较好，有明显衍射峰，且衍射峰尖锐，与PEM混合后，衍射峰没有受到任何影响；傅里叶变换红外光谱分析表明，指示膜各组分结构相似，且具有良好的相容性。当指示膜暴露于氨气中时，其颜色发生显著变化，从最初的紫色逐渐转变为绿色，最终变为蓝色。利用这一特性，对4℃贮藏的羊肉新鲜度进行了监测，结果表明，在第4天和第8天，羊肉分别达到次级新鲜和腐败状态，相应地，指示膜SAL/Ag NPs/PEM2颜色也从紫色变为绿色和蓝色。综上所述，SAL/Ag NPs/PEM2对羊肉新鲜度变化非常敏感，因此可以用于监测羊肉新鲜度。

Abstract:

In order to develop an indicator film that is both pH-sensitive and antibacterial for monitoring the freshness of chilled mutoon, purple sweet potato extract microcapsules (PEM) were prepared. Using sodium alginate and low-acyl gellan gum (SAL) as the base material, with Ag NPs and microcapsules as enhancers. The effects of indicator films (SAL, SAL/Ag NPs, SAL/Ag NPs/PEM) were explored and applied to the monitoring of mutoon freshness. The results indicated that the wall material of PEM had a good encapsulation effect, enhancing the thermal stability of the core material and providing certain antioxidant capabilities. The addition of Ag NPs and PEM improved the mechanical properties, barrier properties, thermal stability, and antioxidant capacity of the single SAL film;specifically, SAL/Ag NPs/PEM2 exhibited the highest tensile strength (12.21MPa) and the lowest oxygen permeability (7.25g·mm/（m2·d）), with a compact and orderly cross-section. X-ray diffraction analysis showed that the crystallinity of Ag NPs was good, with distinct and sharp diffraction peaks, which remained unaffected when mixed with PEM. Fourier-transform infrared spectroscopy analysis indicated that the structures of the components of the indicator film were similar and had good compatibility. When the film was exposed to ammonia gas, its color underwent significant changes, gradually shifting from purple to green and finally to blue. Utilizing this property, the freshness of mutoon stored at 4℃ was monitored. Experimental results demonstrated that on the 4th and 8th days, the mutoon reached secondary freshness and decay states, respectively, corresponding to color changes in the indicator film SAL/Ag NPs/PEM2 from purple to green and blue. In summary, SAL/Ag NPs/PEM2 was highly sensitive to changes in mutoon freshness and can be used for monitoring its freshness.