超高静压对食品真空复合包装膜材料性能及微观结构影响的初探

食品包装材料性能及结构变化会影响食品的质量安全及货架期,探索超高静压对食品包装材料性能及结构变化对了解超高静压对包装材料作用效应机理及包装材料选择是有益的。选择2种食品包装最为常用的未拉伸聚丙烯/尼龙/聚乙烯(CPP/nylon/PE)和聚丙烯/铝/聚乙烯(PP/Al/PE)复合包装膜为研究对象,探讨了不同超高静压强对包装材料拉伸强度、拉伸伸长率、热封强度、透气性、透湿性的变化等影响,并对超高静压对包装材料断面结构的影响进行了环境扫描电镜(ESEM)观察。试验结果表明:(1)超高静压处理对CPP/nylon/PE和PP/AL/PE复合材料拉伸强度影响变化不显著;(2)经超高静压处理后,CPP/nylon/PE伸长率及透氧系数变化显著(P<0.05);(3)经超高静压处理后,PP/Al/PE热封强度、透湿率变化显著(P<0.05)、伸长率及透氧系数变化极显著(P<0.01);(4)在一定压强的超高静压处理会使复合膜结构产生膜间裂缝及Al膜内部裂缝。对CPP/nylon/PE在300-600MPa,PP/AL/PE在200-600MPa,基本上是压强越大,裂缝就越严重。

Preliminary Study on High Hydrostatic Pressure Effects on the Material Characteristics and Structures of the Flexible Multilayer Films for Vacuum Packaging Food

The material characteristics and structure changes of food packing material may impact the food product quality,safety and shelf life.In order to understand the mechanism of high hydrostatic pressure(HHP) on food packing materials and selecting compatible packing material for HHP,it is helpful to study the effects of HHP on the characteristics of packing material.Selecting 2 flexible multilayer films widely used in vacuum food packaging,CPP/nylon/PE and PP/AL/PE as testing targets,we studied the alteration of 5 material characteristics and the cross structures under environmental scanning electron microscopy(ESEM) of the multilayer films before and after being treated with HHP.Five material characteristics are tensile strength,the percent elongation,the heat seal strength,and the rate of oxygen permeance and the rate of the water vapor permeance.The results showed that(1)there was no statistical differences in the tensile strength between the control and the films treated for CPP/nylon/PE and PP/AL/PE;(2) there was a differences(p<0.05) in the percent elongation and the rate of oxygen permeance for CPP/nylon/PE between the control and the treated films;(3) For PP/AL/PE between the control and the treated films,it was found that statistical significant differences(p<0.01) in the percent elongation and the rate of oxygen permeance,and statistical differences(p<0.05) in the heat seal strength and the rate of the water vapor permeance;(4) the micrographs obtained from ESEM confirmed the presence of cracks or fissures between two layers and inner Al film after the certain pressure of HHP treatments.It appeared that the extent of these cracks or fissures tended to increase with increasing pressure between 300MPa～ 600MPa for CPP/nylon/PE and between 200MPa ~ 600MPa for PP/AL/PE.