PLA和PE包装袋对西兰花贮藏品质的影响

Effects of PLA and PE Packaging Bags on Storage Quality of Broccoli

目的考察聚乳酸(PLA)与聚乙烯(PE)袋对西兰花贮藏品质的影响。方法利用透氧仪和透湿仪对市售的PLA和PE膜进行阻隔性测试,并采用该PLA和PE袋包装西兰花,利用色度计和顶空分析仪研究室温和冷藏条件下2种包装袋对西兰花保鲜效果的影响。结果 PLA膜的透湿系数和透氧系数分别为1.241×10-13 g·cm/(cm2·s·Pa)和5.07×10-10 m L·cm/(m2·s·Pa),PE膜的透湿系数和透氧系数分别为1.125×10-14 g·cm/(cm2·s·Pa)和2.87×10-10 m L·cm/(m2·s·Pa)。随着贮藏时间的延长,西兰花的色度由绿变红,由蓝变黄,明度由黑变白;袋中O2气氛浓度先减少后增加,CO2浓度先上升后下降。结论 PLA膜的透湿性和透氧性高于PE膜,冷藏条件下,PLA比PE袋能更有效地抑制西兰花的呼吸作用。

The work aims to investigate the effects of polylactic acid（PLA） and polyethylene（PE） packaging bags on preservation quality of broccoli. The barrier properties of PLA and PE films commercially available were tested via oxygen permeability instrument and water vapor permeability instrument. The PLA and PE bags were used to package the broccoli. The effect of such bags on the preservation effects of broccoli respectively at room temperature and under cold storage condition was investigated by colorimeter and headspace analyzer. The results showed that the water vapor permeability coefficient and oxygen permeability coefficient of the PLA film were respectively 1.241×10-13 g·cm/（cm2·s·Pa） and 5.07×10-10 m L·cm/（m2·s·Pa）; those of the PE film were respectively 1.125×10-14 g·cm/（cm2·s·Pa） and 2.87×10-10 m L·cm/（m2·s·Pa）. With the extended storage period, the color of broccoli changed from green to red, and from blue to yellow. The lightness turned from black to white. The O2 concentration in the bags initially decreased and then increased, while the CO2 concentration was on the contrary. The water vapor permeability and oxygen permeability of PLA film are better than PE film. The PLA bag can inhibit the respiration of broccoli stored under cold storage conditions more efficiently than PE bag.