马铃薯淀粉膜制备工艺优化及活性包装中百里香酚释放动力学

Optimization of the potato starch film preparation process and releasekinetics of thymol in active packaging

为提高食品包装中抑菌剂百里香酚(thymol,THY)的生物利用率以延长食品的货架期,该研究采用介孔二氧化硅(mobil composition of matter No. 41,MCM-41)作为THY的控释载体(THY-MCM-41),以马铃薯淀粉为原料制备马铃薯淀粉活性包装膜。利用L_(9)(3^(4))正交试验探究马铃薯淀粉、甘油、氯化钙和THY-MCM-41质量浓度对包装膜机械、物理以及水蒸气阻隔性能的交互影响,优化马铃薯淀粉活性包装膜最佳制备工艺参数,并在不同储存环境下对最优组合活性包装膜中百里香酚的释放动力学进行研究,构建百里香酚释放预测模型。结果表明,当马铃薯淀粉质量浓度为0.04 g/mL,甘油质量浓度为0.015 g/mL,氯化钙质量浓度为0.005 g/mL,THY-MCM-41质量浓度为0.005 g/mL时,制备的包装膜A综合性能最优,其抗拉强度、溶胀度、水蒸气透过率、透氧性和不透明度分别为7.16 MPa、89.23%、1.42×10^(-10)g/(m·s·Pa)、1.02×10^(-15)cm^(2)/(s·Pa)和1.16 mm^(-1)。电子扫描电镜和傅里叶红外光谱分析均证实了THY-MCM-41均匀地分散在马铃薯淀粉膜中,与马铃薯淀粉之间具有良好的相容性。马铃薯淀粉活性包装膜可控制百里香酚的释放速率,将百里香酚的有效作用时间延长到10 d。其中,百里香酚的释放规律符合一级释放模型(R^(2)> 0.980),其释放行为遵循菲克扩散定律。该研究为智能活性包装膜中活性物质的精准控释提供了理论基础。

Essential oils extracted from natural plants can serve as safe food additives,compared with conventional chemical or synthetic additives.Essential oils have also been incorporated into food packaging materials to impart their bacteriostatic and antioxidant properties.Among them,thymol(THY),a monoterpene phenolic compound extracted from the thyme plant,has been used as a bacteriostatic agent in active packaging materials with functional properties,due to its significant bacteriostatic properties.However,the activity of highly volatile THY is easily affected by the packaging environment.Therefore,appropriate techniques are needed to incorporate the THY into polymer matrices,in order to improve its stability and utilization for controlled release.This study aims to prepare the potato starch films of active packaging,taking the mesoporous nano-silica(mobil composition of matter No.41,MCM-41)as the controlled-release carrier of THY(THY-MCM-41),potato starch as the film-forming substrate,glycerol as the plasticizer,and calcium chloride as the cross-linking agent.Single-factor experiments were carried out to determine the suitable additive ranges of potato starch,glycerol,calcium chloride,and THY-MCM-41 mass concentration in the packaging film.The L_(9)(3^(4))orthogonal test was also implemented to investigate the interactive effects of potato starch,glycerol,calcium chloride,and THY-MCM-41 on the thickness,opacity,moisture absorption(MA),water vapor permeability(WVP),tensile strength(TS),and elongation at break(EB)of the packaging film.The optimal conditions were obtained to prepare the potato starch films of active packaging.A systematic investigation was made to clarify the THY release kinetics in the optimal combination of packaging film at different temperatures and relative humidity(RH)environments.A prediction model of THY release was constructed to optimize the THY.The results showed that the optimal properties of the prepared packaging film A were achieved in the TS,MA,WVP,oxygen permeability(OP)and opacity were 7.16 MPa,89.23%,1.42×10^(-10) g/(m·s·Pa),1.02×10^(-15) cm^(2)/s·Pa,and 1.16 mm-1,respectively,when the mass concentrations of potato starch,glycerol,calcium chloride and THY-MCM-41 were 0.04,0.015,0.005,and 0.005 g/mL,respectively.Scanning electron microscope(SEM)and Fourier-transformed infrared(FTIR)spectroscopy confirmed that the denser and more uniform microstructure of packaging film was observed,where THY-MCM-41 was uniformly dispersed in the potato starch film,indicating better compatibility with potato starch.Thermogravimetric(TG)analysis showed that the encapsulation of MCM-41 improved the stability of THY in the potato starch film.In addition,the release kinetics of THY in the potato starch film of active packaging demonstrated that the initial explosive release was shifted to a subsequent sustained release under different temperature-RH environments.The active packaging film was prepared to effectively control the release rate of THY for the effective time of THY up to 10 d.The release pattern of THY was in accordance with the First-order release model(R^(2)>0.980),and the release index“n”was less than 0.5,indicating that the release behavior of THY followed Fickian diffusion law.This finding can also provide the theoretical foundation for the precise release of active substances in the development of active packaging films.