Migration Regularity Of Toluene From Retort Laminated Films And Its Formation Mechanism

The proportion of flexible composite plastic packaging is growing, in which food packaging is the largest, and its safety cannot be ignored. Retort composite film is multilayer composite membrane that can be heat treated in high temperature, and currently used BOPP/ CPP composite film can effectively extend the shelf life of food. Cooking class cast polypropylene (CPP) film has special characteristics that moisture, heat sealing, heat resistance, so it is often used as the inner layer of the composite retort film substrate. Printing inks and adhesives can be caught in the middle layer of the composite film in retort composite film production process. The solvents of printing inks and adhesives are mainly ethyl acetate and toluene. Residual solvent will migrate into food under certain conditions. The toluene is recognized carcinogen. Long-term consumption of food containing toluene can cause chronic poisoning of the body, threats to human health. Thus, toluene migration and its formation mechanism of resistant cooking compound residual film are important. It provides theoretical foundations for improving the quality of retort composite film and migration of chemical substances, which has a positive social significance and scientific value.In this paper, discuss the migration of toluene mainly from the nature of food, the contact temperature, and contact time three main affecting factors. Analyze the mobility and migration of residual toluene that exist in retort composite films to food simulants and condiments simulants at different temperature and time. At the same time, the performance、 IR, DSC curves and scanning electron microscope photographs of retort composite films that were treated before and after were investigated. The toluene migration mechanism of retort composite film was deduced. The main results are as follows:1. Determine and analyze the toluene migration to food simulants and performance of retort composite film (BOPA/CPP) at different temperature and time. The results of the study are as follows:(1) The toluene migration of retort composite film was rising with increased temperature and prolonged time. Migration was artificially balanced at 121 "C,30min. The sequence of toluene migration was as follows:soybean oil>3%acetic acid>distilled water;(2) High-temperature cooking change retort composite film properties that treated by food simulants. The tensile strength and elongation at break of retort composite film was decreased with increased temperature and prolonged time. The sequence of mechanical properties was as follows:soybean oil>3%acetic acid>distilled water;(3) The toluene migration of retort composite film is 93.54±1.77%at 121℃、 30min treated by soybean. The tensile strength and elongation at break were decreased by 22.16% and 16.47%. The water vapor permanence and oxygen permanence were increased by 166.46%and 75.64%.2. Determine and analyze the toluene migration to condiment simulants and performance of retort composite film (BOPA/CPP) at different temperature and time. The results of the study are as follows:(1) The toluene migration of retort composite film was rising with increased temperature and prolonged time. Migration was artificially balanced at 121℃,30min. The sequence of toluene migration was as follows:5%nacl>0.2%sodium glutamate>10%sucrose>distilled water;(2) High-temperature cooking change retort composite film properties that treated by condiment simulants. The tensile strength and elongation at break of retort composite film was decreased with increased temperature and prolonged time. The sequence of mechanical properties was as follows:5%nacl>0.2%sodium glutamate>10%sucros＞distilled water;(3) The toluene migration of retort composite film is 49.47±1.46%at 121℃,30min treated by nacl. The tensile strength and elongation at break were decreased by 16.58%and 16.85%. The water vapor permanence and oxygen permanence were increased by 152.53% and 67.95%.3. Correlation analysis and Regression analysis between migration of residual toluene in compound film and membrane performance with the cooking conditions. Infrared spectra, DSC curves and SEM photos of CPP film were measured to analyze the toluene migration of retort composite film.(1) Correlation analysis showed that there was a good correlation between the migration rate of residual toluene and the membrane performance with the cooking conditions. Retort composite membrane residual toluene migration rate was a significant positive correlation with temperature, and time was extremely significant negative correlation with simulation of liquid types showed extremely significant positive correlation; composite membrane mechanical propertieswith temperature, time, simulation solution showed a significant negative correlation; composite film barrier properties and temperature, time, simulation solution had a significant positive correlation;(2) The regression analysis showed that the F value and the complex correlation coefficient R of each equation reached a very significant level. The effect of the temperature, time and the type of the simulated liquid on the migration rate and the composite film properties of the residual toluene in the composite film was greatly affected by the temperature and time. The effect of cooking conditions on the quality of the composite film can not be ignored;(3) Infrared spectra showed that:part absorption peaks move to lower wave number that treated by high temperature, distilled water, and soybean oil, especially the peak of 2925 obvious red shift;(4) The DSC curve analysis results show that:Completely melting temperature was increased, melting point and enthalpy decreases of retort composite film that treated by high temperature, distilled water, and soybean oil. It shows that the thermal stability of the film deteriorates, and the degree of crystallinity inside the membrane reducing;(5) Compared the scanning electron microscopy pictures, the result showed that:the section of the control film is relatively smooth, the section of film was uneven and distorted that treated by high temperature, distilled water, and soybean oil compared with the control film.