【作者】 黄崇杏；

【导师】 王志伟；

【作者基本信息】 江南大学 ， 包装工程， 2008， 博士

【摘要】 纸质包装材料以其良好的物理性能、机械操作性能以及环保多方面的优良性能,已成为食品包装工业的重要包装材料。纸质包装材料在生产过程以及后续的加工过程中添加的一些化学物质会残留在纸张中,尤其是残留在纸张中的一些有毒有害物质与食品接触时会向食品发生迁移,从而可能导致食品污染而最终危害消费者的健康。欧美一些发达国家十分关注纸质食品包装材料的卫生安全问题,纸质包装材料污染物的分析、迁移理论等已成为世界性的热点研究方向。本论文对纸质包装材料中的挥发性成分及乙醇萃取液进行了定性和定量分析,分别使用微量点滴法和体积比法研究了食品包装纸中模拟污染物的分配系数Kpaper/air,并对包装纸中有机模拟物的脱附动力学进行了研究;同时,研究了食品包装纸中的模拟污染物向脂肪类食品的迁移行为。研究结果表明:利用固相微萃取法萃取食品包装纸中的挥发性有机污染物时,优化的固相微萃取条件为:100微米PDMS萃取头,顶空方式,萃取温度为60℃,时间为80分钟。当吸附结束时,在270℃的条件下,将其放在GC的注射端解吸2分钟。利用GC-MS分别对固相微萃取法萃取出来的挥发性有机物和乙醇萃取液的分析发现,纸样中含有的挥发性有机物质主要为烷烃、氯代烷烃、邻苯二甲酸酯、酯和醛、醇、芳香族化合物等物质。而纸样抽提液中所含的有机污染物主要为烷烃、氯代烷烃、邻苯二甲酸酯、酰胺类物质、酯和醛、酮、酸、芳香族化合物和杂环类化合物等物质。印刷过的纸样中含有较多的烷烃类物质,脱墨浆中也含有少量的烷烃类物质,说明纸样中的烷烃类物质主要是从印刷过程中带来的。利用微量点滴法测定了白卡纸、牛皮纸和瓦楞原纸中的邻二甲苯、正十二烷、萘、二苯醚和邻苯二甲酸二异丁酯(DIBP)等模拟污染物的分配系数Kpaper/air并绘制了吸附等温线。研究发现,分配系数Kpaper/air与模拟污染物组分、沸点、化学结构、立体结构及纸样的定量、厚度等有密切的关系,纸张的定量和厚度越低,则分配系数也越低。邻二甲苯的Kpaper/air值最小,其次是正十二烷、萘、二苯醚和邻苯二甲酸二异丁酯。挥发性模拟污染物的分配系数Kpaper/air随着温度的增加而降低,说明在高温的情况下,食品包装纸中的污染物会对食品有更大的危害。在体积比法间接顶空气相法测定气-液平衡分配系数(VEL)的基础上,提出了体积比法测定包装纸中有机污染物在纸和空气间分配系数的测定方法。推导出的体积比法测定Kpaper/air值的计算公式为: = ,并对体积比法测定包装纸中的有机污染物的分配系数Kpaper/air的方法进行精确度和真实度的计算分析和实验验证。对精确度而言,5次重复实验的相对偏差为3.6%,峰面积的比值r及纸样的体积比x对测定结果有显著影响。对准确度而言,该方法与“微量点滴法”的结果很接近,从而证实了该方法的有效性。另外,体积比法是一种快速、便捷的方法,既不需要对包装纸样品进行预处理,也不需要知道有机模拟物在纸样上的浓度,非常适合于包装纸中有机污染物在纸和空气中分配系数Kpaper/air的测定。应用了多次顶空萃取气相色谱法(MHE-GC)测定模拟物污染从纸张传质到空气中的脱附反应动力学的方法,从MHE-GC法测定的邻二甲苯、正十二烷、二苯醚和邻苯二甲酸二异丁酯等模拟物污染在不同温度下的反应速率常数来看,随着温度的升高,模拟污染物的脱附反应速率常数随之增大,达到平衡所需时间越短,同时,脱附速率常数受模拟污染物的沸点和化学结构的影响。通过不同温度下模拟污染物从纸张传质到空气中的动力学曲线可知,温度对脱附行为的影响较大,温度越高,模拟污染物脱附达到平衡的时间也越短,其中邻二甲苯在100℃、70℃、40℃时的脱附达到平衡时间大约分别是1h、4h和≥4h。温度对迁移行为有很大影响,实验在25℃、50℃、70℃和100℃的条件下进行研究发现,温度越高,迁移率就越高,而且达到平衡的时间也越短。纸样的定量、厚度及纸浆性质对迁移有一定的影响,纸样的定量越低,迁移率越高,并且更容易达到迁移平衡。全脂奶粉与Tenax作为食物模拟物时,模拟污染物都具有较高的迁移趋势,且其迁移行为十分相似,但是Tenax在高温下的吸附能力反而降低,这是由于Tenax的热解析作用造成的。这也说明,在低温的情况下,Tenax是很好的食品模拟物。同时,奶粉有很好的吸附能力,且其吸附能力比Tenax差一些,能更好代表一般食品的性质,因而作为一种真实的食品非常适用于做迁移研究。此外,奶粉在高温下也有很好的热稳定性,可以在高温下用于做迁移实验的食品模拟物。更多还原

【Abstract】 Due to their unique physical and mechanical properties and environmentally benign feature, paper base package materials are importance for food packaging industries. During manufacture and the subsequent treatment processes, chemicals are added as additives and are generated as byproducts. Some of those chemicals are toxic and can migrate into foods. The migration of harmful substances from these package materials to food results in contamination and thus constitutes a great threat toward public health. the safety and health of paper based packaging materials have increasingly drawn attention in the developed nations, and the researches on the contaminations analysis and in theory establishment for contaminant migration became hot topics.This study is on the quantitative and qualitative determinations of volatile organics and alcohol extractives in paper base package materials. Partitioning coefficients of model contaminants between the packaging materials and air were investigated through microsampling and volume ratio method. Desorption kinetics of model organic contaminants and transfer phenomena of model organic contaminants between package materials and food were also studied. The results obtained are as follows:The study on the optimal conditions for solid phase micro extraction (SPME) of volatile organics in paper base packaging materials showed that the optimized extraction condition is follows: 100μm polydimethylsiloxane (PDMS) SPME fiber was placed in the headspace of paper sample at 60℃for 80min, and the adsorbed organics readily desorbed in a gas chromatography injection port and completed in 2 minutes at 270℃.The SPME extracted volatile organics and ethanol extracts of 20 paper base package samples were analyzed by using GC-MS. It was determined that the major volatile organics in the samples include alkane, chloralkane, alkyl phthalates, aldehyde, ester, alcohol and aromatic compound, naphthalene and phenol, and the main components found in the ethanol extracts consist of alkane, chloralkane, alkyl phthalates, amide, aldehyde, ester, ketone, carboxylic acid, aromatic compounds and heterocyclic compounds. The contents of the alkane in the unprinted paper or the deinked handsheet are less than those in printed ones,that indicates the sourses of hydrocarbon is during printing process.Partition coefficients (Kpaper/air) of o-xylene, dodecane, naphthalene, diphenyl oxide and diisobutyl phthalate in cartonboard, kraft and fluting medium were determined by microsampling and the adsorption isotherms of the contaminants were plotted. Results indicated that it was obviously that not only the boiling point of the model compounds, but also the chemical properties and the stereochemistry of the compounds play important role in their Kpaper/air value. Kpaper/air value had a proportional relationship with the grammage and the thickness of paper sample. The lower of the grammage and the thickness, the lower of Kpaper/air value would be. Kpaper/air values of selected model compounds increased in this order: o-xylene, dodecane, naphthalene, diphenyl oxide, diisobutyl phthalate. Kpaper/air decreased with an increasing temperature, which indicated that the comtaminants in paper and board packaging materials is more dangerous to food at high temperature. Based on the theory of indirect headspace gas chromatographic method for vapor-liquid phase equilibrium study, volume ratio method was developed to measure the partition coefficient of organic contaminants between paper base packaging materials and air, Kpaper/air. The derived calculation procedure to determine Kpaper/air is , precision analysis and accuracy of the method was experimental verifiied and mathematical analysed. It was found that the relative standard deviation of 5 repeating determinations was 3.6%. The ratio of peak area and the sample volume had significant effect on the testing result. Comparing to the microsampling procedure, volume ratio method was similar in term of their accuracy. The volume ratio method was further validated with the calculations and tests. It was concluded that the volume ratio method was a fast and convenient procedure; it requires neither sample pretreatment nor the information of organic contaminants prior to the test. Consequently, the method is suitable for the determination of Kpaper/air of organic contaminants.A procedure has been applied to determine the transferring kinetics of model contaminants from paper base packaging materials to air through multiple headspace extraction (MHE-GC). The procedure was applied to study the kinetics of selected contaminants (o-xylene, dodecane, diphenyl oxide, diisobutyl phthalate) desorbing from paper and transferring to air. Results indicated the desorption reaction rate constant increased with an elevated temperature. The boiling point and chemical structure of model contaminants also affects the desorption reaction rate constant. Temperature constitutes a predominant effect on the desorbing kinetics of contaminants. The equilibrium time of desorption decreased with an increasing temperature, and the equilibrium time of model contaminants, o-xylene at 100℃,70℃,40℃, are 1h,4h and≥4h, respectively.Temperature had great effect on the migration of the organic contaminants. In the temperature range studied(25℃,50℃,75℃and 100℃), migration rate increased with an increasing temperature, whereas desorbing equilibrium time decreased with an elevating temperature. The grammage and thickness of the paper samples affected the migration rate. The lower the grammage and thickness, the higher of the migration rate and the easier to reach desorbing equilibrium. Whole milk and Tenax displayed similar results in terms of their adsorbing capacity. Both of them demonstrated high adsorption toward the selected model compounds, although Tenax showed a poorer adsorption under an elevated temperature. This may attribute to the thermal degradation of Tenax. Result thus indicated that Tenax is a very good food model for experimental study under low temperature. As a real food, powder mill posses great adsorption capacity and is stable under elevated temperature. As a result, powder mill is a good candidate for the migration studies.更多还原