Properties of polyethylene films with incorporated benzoic anhydride and/or ethyl and propyl esters of 4-hydroxybenzoic acid and their suitability for food packaging.

Benzoic anhydride and ethyl and propyl esters of 4-hydroxybenzoic acid (ETP and PRP, respectively, also termed parabens) incorporated into low density polyethylene (LDPE) film were studied with regard to migration into food and food simulants at 6 degrees C and 25 degrees C, and changes in selected properties of the film were investigated. Antimicrobials were incorporated into polymer film in concentrations of 5 g/kg and 10 g/kg. The addition of parabens into the polymer was more difficult than benzoic anhydride due to their volatility. For benzoic anhydride, 30-40% and 10-20% of the added amount was found to leach from the film into aqueous and olive oil food simulants, respectively. The migration into both water and olive oil followed a very similar course in the case of parabens. Migration levels over 90% and in the range of 70% to 80%, relative to the amount of agent in the film, were determined for ETP and PRP respectively. The incorporation of antimicrobials into the film significantly changed the functional characteristics of the packaging material, i.e. permeability of oxygen, carbon dioxide and water vapour, tensile strength, coefficient of friction, sealing strength and transparency. Shelf life tests with packaged cheese and toasted bread demonstrated the efficiency of the film containing 10 g/kg of BA against mould growth on the food surface during storage at 6 degrees C.