Sorption Behavior of Flavor Compounds into Packaging Films from Ethanol Solution

The sorption of flavor compounds into low-density polyethylene (LDPE) and ethylene-vinyl alcohol copolymer (EVOH) films was greatly influenced by ethanol concentration, and maximal sorptions were observed at 5-10% (v/v) ethanol for LDPE and 10-20% (v/v) ethanol for EVOH. The sorptions of ethyl hexanoate, octanal, and octanol into LDPE film were ∼1.7, 16.5, and 2.5 times higher than those in the 0% (v/v) ethanol solution, respectively (for EVOH film, the sorption increments of these compounds were ∼6.2, 3.5, and 4.1 times, respectively). To better understand this phenomenon, the solvent properties of ethanol solutions were investigated. The dielectric constants were roughly unchanged in the range 5-15% (v/v) ethanol. According to the results obtained by ¹H NMR measurement, in which the difference in proton chemical shift from water-d (HDO) and ethyl alcohol-d (EtOD) became maximum at 23% (v/v) ethanol solution, the structural change of water induced by the addition of ethanol would be great up to 23% (v/v) ethanol. These results accurately reflected the sorption behavior. Therefore, the specific sorption behavior of flavor compounds from an ethanol solution would be brought about by the heterogeneous water-ethanol structure.