Study On Radiolysis Products, Migration, And Physical Prties Of⁶⁰Co-γ Irradiated Food-grade PVCD Films

With the development of food irradiation, safety of irradiated food becomesincreasingly important. As directly contacting with food, the effects of irradiation onthe food packaging are bound to cause the change of the food quality. Among suchpolymers,“PVDC”（polyvinylidene-chloride） has been applicated as many kinks offood packaging because of its superior performance. So study on the properties ofirradiated food-grade PVDC films is timely and meaningful.The5kinds of⁶⁰Co γ-irradition food-grade PVDC films are chosen as researchobjects in this study. According to the effects of irradiation on food packaging, thestudy is devided into several groups.（1） An analytical method based on gas chromatography-mass spectrometry（GC-MS） developed for determining26plasticizers and3antioxidants in foodpackaging. The results showed that the calibration curves had good liner relationship（r²>0.99） and the LOD were between0.01～6.4×10^-3mg/L （S/N=3）. The recoveryranges were from55.7%to114%with the RSD was less than16.7%for29compounds, and could be successfully applied in determining26plasticizers and3antioxidants in food-grade PVDC films. The method was then applied to thedetermination of29compounds in5kinds of food-grade PVDC films. The resultsshowed that the contents and migration levels of plasticizers–DIBP, DBP, DEHP,BXA and antioxidant-BHT were higher in films while the obtained values were withinthe limits set by EU.（2） By GC-MS analysis method, determinate volatile components and theirmigration into n-hexane of5kinds of irradiated food-grade PVDC films with dose of3¹00kGy. The results showed that the contents and migrations of hydrocarbons,alcohols, carbonyl compounds, carboxylic acid and esters had remarkable diversity in irradiated food-grade PVDC films. Among such compounds, the change of additivesand their radiolysis products were obvious and had strong regularity. With increasingirradiation dose, the contents and migration levels of antioxidant-BHT, plasticizers-DIBP、DBP、DEHP and13-Docosenamide decreased while the contents and migrationlevels of1,3-DTBB,2,4-DTBP and2,6-Di-tert-butyl-1,4-benzoquinone increased.（3） An analytical method based on high liquid chromatography-massspectrometry （HPLC-MS/MS） with electrospray ionization （ESI） adopted fordetermining8antioxidants in food packaging. The results showed that the calibrationcurves had good liner relationship （r²>0.93） and the LOD were no more than4.1×10^-3mg/L （S/N=3）. The recovery ranges were from65.0%to100%with the RSD was lessthan15.7%for8antioxidants. The method was then applied to the determination of8antioxidants in5kinds of irradiated food-grade PVDC films with dose of0¹00kGy.The results showed that the contents and migration levels of Irganox1076、Irgafos168、Irganox1010were higher in films and decreased with increasing irradiationdose.（4） Refer to national voluntary standards, determinated tensile strength andelongation, oxygen permeability and water vapor permeability, chromaticity valuesand melting temperature and melting enthalpy of5kinds of food-grade PVDC filmswith dose of0¹00kGy. With increasing irradiation dose, tensile strength andelongation of films first increased and then decreased, melting temperature andmelting enthalpy, oxygen permeability of films decreased while water vaporpermeability first decreased and then increased. The films became more darkness,yellow, green and color difference values increased with increasing irradiation dose.Based on experimental data, it could be postulated that color difference values forPVDC may be proposed as a basis for developing a method to monitor intensity ofirradiation. Furthermore, a method was established for simultaneous determination of19polycyclic aromatic hydrocarbons （PAHs） in grilled meal samples using GC-MS.Through the optimization of pre-treatment conditions, the samples were extractedwith n-hexane-dichloromethane and then purified by gel permeation chromatography（GPC）. The results showed that the calibration curves had good liner relationship（r²>0.99）. The recovery ranges were from58.0%to122%with the relative standarddeviations （RSD） was less than21.4%for PAHs. The method was then applied to thedetermination of PAHs in different parts of the lamb barbecue.19PAHs were found tobe present at levels ranging from0.3to74.7μg/kg. The method was accurate, simpleand rapid to analyze19PAHs in grilled meal samples.