Thermodynamic Elucidation of Depression Mechanism on Sorption of Flavor Compounds into Electron Beam Irradiated LDPE and EVA Films

Electron beam irradiation for low-density polyethylene (LDPE) film up to 20 Mrad resulted in specific sorption depression behaviors of volatile compounds. The sorptions of octane, ethyl hexanoate, and d-limonene into irradiated film were depressed, whereas the opposite behavior was obtained for octanal and octanol. To elucidate these specific phenomena, a thermodynamic attempt of applying the solubility parameter (SP) value was done. As a result, the sorptions of all hydrocarbons and methyl and ethyl esters composed of more than six carbon atoms corresponding to <8.59 SP value were depressed in all, while sorption promotion was observed for all alcohols. A similar result was obtained for irradiated EVA film, for which the sorption depression was observed only for the volatile compound with <8.93 SP value. Calculating the ratio of SP value of volatile compound (δ_F) to that of irradiated film (δ_P), the ratios (δ_F/δ_P) for irradiated LDPE and EVA films gave good agreement at 1.09.