肉桂精油微囊的制备及对柑橘采后病原菌的抑制作用

Preparation and Inhibitory Effect of Cinnamon Essential Oil Microcapsules on Citrus Postharvest Pathogenic Fungi

为进一步开发植物精油在柑橘采后防腐保鲜中的应用,以肉桂精油为芯材,玉米糊精、阿拉伯胶、明胶为壁材,采用复合凝聚-冷冻干燥法制备肉桂精油微囊。通过扫描电镜和激光粒度仪考察精油微囊的微观形貌结构,采用傅里叶红外光谱和差示扫描量热法探究其分子间相互作用和热稳定性,运用琼脂扩散法和显微观察分析其抑菌作用。结果表明,EDA_(1)G_(2)和EDA_(3)(不含明胶)2种精油微囊呈近球形结构,对肉桂精油包埋性良好、分散均匀,平均粒径分别为49.2 μm和11.56 μm,粒径分布集中;红外光谱揭示肉桂精油被包埋在微囊中,且壁材和芯材间并不是简单的物理混合,也没有形成新的化学键,可能发生非共价键结合;DSC显示2种微囊热稳定性良好;肉桂精油和微囊均对指状青霉、意大利青霉和地霉菌株展现明显的抑菌作用,可显著抑制孢子萌发和菌丝伸长,意大利青霉的菌丝有解体的趋势,且EDA_(1)G_(2)对意大利青霉的抑制更为明显。该结果将为柑橘采后防腐保鲜中的研究和应用提供理论依据。

In this study,to further develop the application of plant essential oil(EO) on the preservation of citrus postharvest,cinnamon EO was used as the core material and corn dextrin,gum arabic and gelatin as the wall material,and cinnamon EO microcapsules were prepared by the combined coagulation-freeze drying method.The microstructure of the EO microcapsules were investigated by scanning electron microscopy and laser particle size analyzer.The molecular interaction and thermal stability of the EO microcapsules were investigated by Fourier transform infrared spectroscopy and differential scanning calorimetry.The antifungal activity of the EO microcapsules was analyzed by agar diffusion method and microscopic observation.The results showed that EDA_(1)G_(2) and EDA_(3) (without gelatin) had a nearly spherical structure,which showed good embedment ability and uniform dispersion for cinnamon EO.The average particle sizes were 49.2 μm and 11.56 μm,respectively,and the particle size distribution was concentrated.FTIR revealed that cinnamon EO was embedded in microcapsules,and there was no simple physical mixing between wall and core materials,and no new chemical bonds were formed,which may result from non-covalent bond.DSC showed that the two types of microcapsules had good thermal stability.Both cinnamon EO and microcapsules showed obvious inhibitory effects on Penicillium digitatum,P.italicum and Geotrichum citri-aurantii strains,and could significantly inhibit spore germination and mycelium elongation.The mycelium of P.italicum showed a tendency of disaggregation,and EDA_(1)G_(2) showed more obvious inhibition on P.italicum.This study will provide a theoretical basis for the research and application of citrus postharvest preservation.