The effect of high pressure processing on the mass transfer of Irganox 1076 in low-density polyethylene films and in 95% ethanol as a food simulant

High pressure processing (HPP) is used to treat foods packaged in flexible polymeric pouches but little is reported on how HPP affects mass transfer and morphology of these polymers. The objective of this study was to correlate high pressure and storage temperature with migration, sorption, morphology, permeability, crystallinity and thermal properties of low density polyethylene films (LDPE).For the methodology, in one set of experiments, pouches made from the LDPE films were filled with food simulants, high pressure treated then stored for up to 7 days. Control samples were similarly stored but not pressure treated. Irganox 1076 in the films and food stimulants was quantified by HPLC. In a second set of experiments, the pouches, filled with 95% ethanol, were made from LDPE films having Irganox 1076. After applying 600MPa pressure, the concentrations of Irganox 1076 in the pouches and 95% ethanol were measured by HPLC after 25, 50 and 65°C storage. In the third part of experiments, pouches made from the LDPE films were filled with 95% ethanol then high pressure processed. Then, the pouches were opened, the liquid empted and the pouches dried. Crystallinity, permeability and thermal properties of the LDPE film samples were then measured using OX-tran, differential scanning calorimetry (DSC), dynamic mechanical calorimetry (DMA) and X-ray diffraction testing methods.The results of these tests showed that the migration of Irganox 1076 to and from the LDPE films, increased in the presence of high pressure when compared with the controls. The results also showed that increasing storage temperatures caused increasing concentrations of Irganox 1076 to migrate from the films to the food simulant. Results from the permeation studies showed that oxygen permeation through the films decreased when the material was exposed to HPP. The DSC analysis showed no detectible change in the enthalpy of fusion and crystallinities within the LDPE films but increase in its melt temperature was seen after the HPP treatment. However, x-ray diffraction tests showed increasing crystallinities as the level of the HPP treatment increased. The results of the DMA showed that the increase in pressure caused increases in storage modulus (P < 0.05).