纳米氧化锌改性LDPE食品包装薄膜中锌粒子的迁移规律

Migration rules of Zn from nano-ZnO modified LDPE food packaging films

为探究纳米氧化锌改性(low-density polyethylene,LDPE)薄膜中纳米锌粒子的迁移规律,依照欧盟法规(EU)No.10/2011,分别采用蒸馏水、30 g/L乙酸溶液、体积分数10%的乙醇溶液、体积分数95%的乙醇溶液作为中性、酸性、脂肪性和酒精性食品模拟物,研究在不同温度条件下(40、70℃)纳米锌粒子的迁移情况,同时探究微波和紫外处理对迁移结果的影响。研究发现,纳米锌粒子在4种食品模拟物中的迁移量从高到低依次为:酸性食品模拟物、中性食品模拟物、酒精性食品模拟物和脂肪性食品模拟物,并且随温度的升高,纳米锌粒子的迁移量增大。此外,微波处理能促进纳米锌粒子的迁移,而紫外处理则没有促进效果。纳米锌粒子的迁移量范围为0.52~14.17 mg/kg。根据欧盟规定所允许的最大迁移量5 mg/kg,迁移试验表明纳米氧化锌改性LDPE薄膜还需要进一步开展减少纳米粒子迁移的研究工作,以确保其在食品包装中的安全使用。

In order to study the migration of Zn from low-density polyethylene（LDPE） films modified with nano-ZnO,according to the European Union regulation NO.10/2011,distilled water,30 g/L acetic acid,95% ethanol（v/v） and 10% ethanol（v/v） were chosen as the neutral,acidic,fatty and alcoholic food simulants,respectively.Nanoparticle modified films（NMFs） were prepared by blending LDPE with nano-ZnO.Film characterization was conducted by transmission electron microscope（TEM） and the migration of Zn was measured by ICP-MS（inductively coupled plasma-mass spectrometry）.Migration tests of Zn into 4 kinds of food simulants were performed under 40 ℃ for 2 h,1 d,4 d and 7 d,as well as 70 ℃ for 2 h.The effect of different temperatures on the migration was studied.Moreover,the influences of microwave and ultraviolet treatment were also studied.The size of nano-ZnO was observed to be about 100 nm in TEM image.This result indicated that particles in the NMFs still possessed nano size.It was obvious that NMFs had relatively higher content of Zn compared to the control in all kinds of food simulants.For NMFs in neutral simulant,the migration amount of Zn in 40 ℃ for 7 d was 10% higher than that in 40 ℃ for 1 d.While in acidic simulant,the migration amount of Zn in 40 ℃ for 7 d was 31% higher than that in 40 ℃ for 1 d.Migration amount of Zn in 40 ℃ for 7 d were 4% and 9% higher than that in 40 ℃ for 1 d,respectively,in alcoholic and fatty simulants（P〈0.05）.Results showed that the highest migration amount of Zn was in acidic simulant,followed by neutral,fatty and alcoholic simulants.The amounts of migration rose with the increase of temperature.In neutral simulant,the migration amount of Zn in 70 ℃ for 2 h was 1 245% higher than that in 40 °C for 2 h.When in acidic simulant,the migration amount of Zn in 70 ℃ for 2 h was 1 047% higher than that in 40 °C for 2 h.Migration amounts of Zn in 70 ℃ for 2 h were 902% and 1 524% higher than that in 40 ℃ for 2 h in alcoholic and fatty simulants,respectively（P〈0.05）.Microwave treatment could promote the migration.In neutral simulant,compared to the control,microwave treatment of 250 and 600 W increased the migration amount of Zn by 22% and 53%,respectively.While in acidic simulant,migration amount of Zn was enhanced by 22% and 53%,under microwave treatment of 250 and 600 W,respectively（P〈0.05）.However,ultraviolet treatment could not promote the migration of Zn.The amounts of Zn migrated into food simulants ranged from 0.52 to 14.17 mg/kg.The highest migration amount of Zn was beyond the limitation of 5 mg/kg in the European Union regulation No.10/2011.The results of migration test indicated that LDPE films modified with nano-ZnO might not be a kind of safe food packaging film,and it still needs further investigation.