Estudo da cinética da migração de aditivos de embalagem de polipropileno à margarina

Abstract

Polymeric containers are used to store food in order to ensure product quality. Adverse storage conditions can lead to migration of constituents from the package to the food matrix, particularly those of fat source. These constituents are derived from the polymerization. Moreover, additives are added to improve the physical and chemical properties of the materials. The food-packaging interaction is allowed by the diffusion mechanism, as a result of the reactivity of these compounds. The issue that guides the study is the change in sensorial properties of the margarine and toxicological aspect. In addition, migration mechanisms are influenced by the exposure conditions of time and temperature because they affect solvation at the polymer-food interface, food matrix dispersion and diffusion of the substance in the polymeric matrix. The application of higher temperatures results in thermal decomposition of the polymer components. Aiming to identify the possible presence of additives and polypropylene packaging fragments in margarine samples kept at room temperature and under refrigeration during 92 days, the methodology was developed based on high performace liquid chromatography analysis (HPLC). In the study, the identification was made comparing the maximum absorbance of the compounds with the retention time of the substances of interest. The treatment of the samples was made using ethanol as extractor solvent aiming the lipid separation in Soxhlet. The mobile phase presented elution gradient of 65% acetonitrile (ACN) and 35% water (H2O) in the first two minutes then adopted ratio of 100% ACN for the next 13 minutes, returning to the initial percentage for 5 minutes. The extraction method was proved to be appropriate. The method estimated the identification of 2,2-bis-4 hydroxyphenyl propane (BPA) and phthalate, di-2-ethylhexyl phthalate (DEHP), a plasticizer and an antioxidant, respectively, both with detrimental health effects. The physical process was described using considerations expressed as a function of the "Fick's second law" to diffusivity, of the migrant concentration profile in the polymer and the diffusion coefficient of the migrant. Temperature effects were considered in the diffusion coefficient using "Arrenhius equation”, because of migrant concentration. The description of the migration kinetic of the contaminant was linked to the measurement of the concentration profiles during the storage times.