纳米氧化锌/低密度聚乙烯膜中锌向食品的迁移研究

Migration of ZnO from nano ZnO/low density polyethylene film into food

目的研究纳米氧化锌/低密度聚乙烯膜(low density polyethylene film,LDPE)中锌(Zn)向食品的迁移行为,探究其迁移规律。方法选取2种食品模拟物(3%乙酸及超纯水)及真实食品(食用白醋及瓶装水),在3种不同实验温度下(70、40及20℃),研究锌向食品模拟物的迁移规律。采用扫描电子显微镜(scanning electron microscope,SEM)和原子力显微镜(atomic force microscope,AFM)表征纳米ZnO/LDPE膜的表面形貌。结果锌向酸性模拟物中的迁移率远远大于水性模拟物中的迁移率,其中锌向酸性模拟物中的最大迁移率分别为22.7%,20.3%及18.6%(ZL-1,ZL-2及ZL-2#),向水性模拟物中的最大迁移率分别为9.9%,5.7%及4.9%(ZL-1,ZL-2及ZL-2#);锌向酸性食品的迁移量(1.59~5.03 mg/g)同样高于向水性食品的迁移量(2.98~24.60μg/g);随着纳米ZnO的初始含量变大迁移率变小;而偶联剂的加入对锌的迁移有一定的抑制作用。随着纳米ZnO浓度的增加,在薄膜中观察到纳米ZnO的不规则形貌。结论纳米ZnO/LDPE膜不适合在高温下包装食物,且其在酸性食品中的安全隐患高于水性食品。

Objective To investigate the migration behavior of zinc （Zn） into foods in nano ZnO/low density polyethylene （LDPE） films and explore the migration mechanism. Methods Two food simulants （3% acetic acid and ultrapure water） and real food （white vinegar and bottled water） were selected. At 3 different experimental temperatures （70, 40, and 20 ℃）, the migrations of zinc into food simulants were investigated. Surface morphology of nano ZnO/LDPE films were observed by scanning electron microscope （SEM） and atomic force microscope （AFM）. Results The mobility in the zinc-acidic simulants was much greater than that in the water-based simulants, the maximum migration rates in the zinc-to-acid simulants were 22.7%, 20.3% and 18.6%, respectively （ZL-1, ZL-2 and ZL-2#）, and the maximum migration rates to water-based simulants were 9.9%, 5.7% and 4.9%, respectively （ZL-1, ZL-2 and ZL-2#）. The migration of zinc to acidic food （1.59-5.03 mg/g） was also higher than the migration to water-based food （2.98-24.60 ~tg/g）. With the increase of the initial content of nano-ZnO, the mobility became smaller, and the addition of coupling agent had a eertain inhibitory effect on the migration of zinc. With the increase of nano-ZnO concentration, irregular morphology of nano-ZnO was observed in the film. Conclusion The nano-ZnO/LDPE film is not suitable for packaging food at high temperatures, and its safety risk in acidic food is higher than that in water-based food.