两亲性碳纳米管构筑活性保鲜膜对蓝莓货架期品质的影响

    Effects of amphiphilic carbon nanotube constructed active cling film on blueberry shelf life quality

    • 摘要: 针对多壁碳纳米管(multi-walled carbon nanotubes,MWCNTs)固有疏水性制约其在食品包装应用的问题,该研究采用物理吸附-化学接枝协同改性法构建两亲性(hydroxypropyl methylcellulose/acid catalyzed oxidation - multi - walled carbon nanotubes,HPMC/AO-MWCNTs)复合体系,实现纳米材料在食品级高分子基体(derivative ternary tissue,DTT)表面的可控负载。制备出两亲性多壁碳纳米管基活性保鲜膜(hydroxypropyl hethylcellulose-carbon nanotube-based self-assembled layer-active packaging film,HM-CSA-AP),在3层组装时展现出最优性能:拉伸强度达68.44 MPa,较DTT层提升27.85%;阻氧率提高62%,水蒸气透过率下降64%,形成致密“迷宫效应”阻隔层。HM-CSA-AP中大肠杆菌和酵母菌菌落数与DTT相比,分别下降61.44%、64.37%,源于HPMC/AO-MWCNTs释放与物理穿刺的协同作用。在蓝莓保鲜试验中,HM-CSA-AP展现出卓越的货架品质维持能力:25 ℃储藏12 d后,果实硬度保持在3.86 N为空白对照组的2倍左右;丙二醛含量(20.46 mmol/g)显著低于空白对照组(51.34 mmol/g)(P<0.05);维生素C含量(47.47 mg/100 g)为空白对照组的3倍左右。其保鲜机制包括:高阻氧特性抑制呼吸代谢,低透湿性延缓果胶酶活性,以及纳米管负载抗氧化剂的协同抑菌作用。该研究所构建的HM-CSA-AP体系在阻氧性和透湿特性方面协同优化,为环境友好型活性食品包装材料的开发提供了创新解决方案,在浆果类生鲜储运领域具有重要应用价值。

       

      Abstract: Multi-walled carbon nanotubes (MWCNTs) have restricted their application in food packaging, due mainly to the inherent hydrophobicity. In this study, a synergistic physical adsorption-chemical grafting modification was proposed to construct an amphiphilic HPMC/AO-MWCNTs (hydroxypropyl methylcellulose/hydropropropropyl methylcellulose) composite. Acid-Catalyzed Oxidation-MWCNTs composite system was obtained to realize the controlled loading of nanomaterials on the surface of a food-grade DTT (derivative ternary tissue) matrix. The amphiphilic HM-CSA-AP (hydroxypropyl methylcellulose-carbon nanotube-based self-assembled layer-active packaging film) was prepared after modification. The results show that the optimal performance was achieved when assembled in 3 layers. Among them, the tensile strength reached 68.44 MPa, which was 27.85% higher than that of the DTT layer; The oxygen barrier rate increased by 62%, whereas, the transmission rate of water vapor decreased by 64%, which was 55.10% higher than that of PE (polyethylene) film and 25.11% lower than that of PVDC (polyvinylidene chloride) film. Compared with the PVDC membrane, the oxygen barrier rate increased by 56.25%, whereas, the transmission rate of water vapor decreased by 22.83%. A dense barrier layer was formed with the labyrinth effect. The number of E. coli, S. aureus, yeast, and mold colonies decreased by 61.44%, 50.72%, 64.37%, and 52.90%, respectively, in the HM-CSA-AP at the number of the self-assembled layers of 3, compared with the DTT; The number of colonies decreased by 53% to 64%, and 54% to 65%, respectively, compared with the PE and PVDC film. The decrease was attributed to the synergistic effect of physical puncture from the HPMC/AO-MWCNTs release. The blueberry preservation experiment showed that the HM-CSA-AP shared excellent shelf quality: The weight loss rate of blueberries increased most slowly after 12 d of storage at 25℃, with the maximum weight loss rate of only 1.17%; The spoilage rate was 15.44%, which was significantly lower than that of the blank control group at the 8th day (22.17%, which had basically lost its edible value); The hardness of fruit was maintained at 3.86 N, which was 2.01 times higher than that of the blank control group; The malondialdehyde content (20.46 mmol/g) failed to reach 1/2 of the blank control group (51.34 mmol/g); The vitamin C content (47.47 mg/100 g) was about three times that of the blank control group; The titratable acid declined 13.35% on day 6 of storage, compared with day 0 of storage. The slowest decrease was observed, compared with the rest groups. The preservation mechanisms also included the inhibition of respiratory metabolism by the high oxygen barrier properties, the retardation of pectinase activity by the low moisture permeability, and synergistic bacterial inhibition by nanotube-loaded antioxidants. The HM-CSA-AP system was synergistically optimized, in terms of the oxygen-blocking and moisture-permeable properties. The dispersion stability of nanomaterials was obtained after optimization. The finding can also provide an innovative solution to the environmentally friendly active food packaging for freshness storage and transportation in the field of berries and fruits.

       

    /

    返回文章
    返回