金丝桃素-β-环糊精络合物的制备及其在小龙虾保鲜膜中的应用

Preparation of hypericin-β-cyclodextrin complex and its application in crayfish cling film

目的探究魔芋葡甘露聚糖(konjac glucomannan,KGM)、海藻酸钠(sodium alginate,SA)、巴西棕榈蜡(carnaubawax,CW)与金丝桃素-β-环糊精络合物(hypericin-β-cyclodextrin complex,Hyp-β-cd)制备的光敏性保鲜膜在4℃储藏条件下对小龙虾的品质影响。方法将制备的Hyp-β-cd加入到KGM、SA与CW溶液中,采用流延法制备光动力杀菌保鲜膜(KGM/SA/CW/Hyp-β-cd膜),通过核磁共振光谱(nuclear magnetic resonance spectroscopy,NMR)与荧光猝灭法验证了Hyp-β-cd的形成和活性氧(reativ oxygen species,ROS)的生成能力,然后用正交实验法对复合膜的制备进行优化。通过扫描电子显微镜(scanning electron microscope,SEM)、傅里叶红外光谱(Fourier transform infrared spectroscopy,FTIR)、X射线衍射(X-ray diffrction,XRD)进行表征,最后,以pH、总挥发性盐基氮(total volatile basic nitrogen,TVB-N)、菌落总数及硫代巴比妥酸反应物(thiobarbituric acid reactants,TBARS)值做为指标对保鲜效果进行评估。结果NMR及荧光猝灭的结果表明Hyp-β-cd的形成和ROS的生成,通过正交实验法对复合膜的制备进行优化:KGM含量为0.7%(m/V,下同)、SA含量为1.2%、CW含量为0.6%、Hyp-β-cd含量为0.4%时,复合膜有最优机械性能,拉伸强度为51.84MPa,断裂伸长率为14.27%。SEM证明了各物质在复合膜中的均匀分布。FTIR与XRD结果表明,随着SA、CW与Hyp-β-cd的加入,KGM与SA之间形成氢键,提高了复合膜的物理性能,CW的加入减少了复合膜的微孔隙,其中水接触角从67.5°增加到88.7°,氧气透过率从32.96降低到22.37 m^(3)·μm/m^(2)·day·kPa。由KGM/SA/CW/Hyp-β-cd膜包裹且在黄色LED光源照射处理后的小龙虾,在第8d时TVB-N值为20.37mg/g,菌落总数为6.14lgCFU/g,TBARS值为0.85 mg/kg,pH超过7.6。结论KGM/SA/CW/Hyp-β-cd复合膜具有作为光敏性抗菌包装材料的潜在应用价值。

Objective To investigate the effects of photosensitive cling film prepared by konjac glucomannan(KGM),sodium alginate(SA),and Brazilian carnauba wax(CW)with hypericin-β-cyclodextrin complex(Hyp-β-cd)on the quality of crayfish under the storage condition of 4°C.Methods The prepared Hyp-β-cd was added into KGM,SA,and CW solutions.The photodynamic sterilizing cling film(KGM/SA/CW/Hyp-β-cd film)was prepared by casting method.The formation of Hyp-β-cd and the ability to generate reactive oxygen species(ROS)were verified by nuclear magnetic resonance spectroscopy(NMR)and fluorescence bursting method.Then,the composite film preparation was optimized using the orthogonal experimental method.and the composite membranes were characterized by scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR)and X-ray diffraction(XRD),and finally,pH,total volatile basic nitrogen(TVB-N),total colony counts,and thiobarbituric acid reactants(TBARS)values were used as indicators to evaluate the freshness preservation effect.Results The results of NMR and fluorescence burst showed the formation of Hyp-β-cd and the generation of ROS,and the preparation of the composite film was optimized by orthogonal experimental method:The composite film had the optimal mechanical properties when the content of KGM was 0.7%(m/V,the same below),the content of SA was 1.2%,the content of CW was 0.6%,and the content of Hyp-β-cd was 0.4%;the tensile strength was 51.84 MPa,the elongation at break was 14.27%.SEM proved the uniform distribution of each substance in the composite membrane,and the FTIR and XRD results showed that with the addition of SA,CW and Hyp-β-cd,hydrogen bonding was formed between KGM and SA,which improved the physical properties of the composite membranes,and the addition of CW reduced the microporosity of the composite membrane,in which the water contact angle was increased from 67.5°to 88.7°,and the oxygen transmittance was reduced from 32.96 to 22.37 m^(3)·μm/m^(2)·day·kPa.Crayfish wrapped by KGM/SA/CW/Hyp-β-cd membranes and treated with yellow LED light source irradiation showed TVB-N value of 20.37 mg/g,colony total of 6.14 lg CFU/g,TBARS value of 0.85 mg/kg,and pH of more than 7.6 on the eighth day.Conclusion KGM/SA/CW/Hyp-β-cd composite films have potential applications as photosensitive antimicrobial packaging materials.