Influence of trace metals, acids and ethanol in food-simulating liquids on the retention of α-tocopherol in low-density polyethylene film

The retention of alpha-tocopherol (vitamin E) in low-density polyethylene (LDPE) film was investigated when in contact with different food-simulating liquids. Variations of the aqueous food simulants approved by the EU for testing of interactions between packaging materials and food, and an alternative fatty food simulant (95% aqueous ethanol) were used to study the influence of trace metals and acids, as well as variation in pH and ethanol concentration, on the stability of alpha-tocopherol in the LDPE film. The presence of trace metals in aqueous media accelerated loss of alpha-tocopherol from the film, while the addition of citric or ascorbic acid counteracted this loss. In contact with aqueous ethanol at a concentration of 50% or higher, the loss of alpha-tocopherol from the film was total. However, with solutions containing less than 50% ethanol, the antioxidant was almost completely retained in the film, unless the temperature was increased from 6 to 40 degrees C. For contact with solutions containing ethanol or trace metals, an increase in temperature resulted in a greater loss of alpha-tocopherol from the LDPE film.