Release of α-Tocopherol from Poly(lactic acid) films, and its effect on the oxidative stability of soybean oil Original Research Article

Poly(94% l-lactic acid) (PLA) films (PT0) and PLA films containing 2.58% wt. α-Tocopherol (PT2.5) were extruded in a pilot-plant size blown-extrusion machine. PT2.5 films were obtained with a slightly yellowish color and absorption of UV–visible light at 320–260 nm. The kinetics of release of α-Tocopherol from the PT2.5 films to ethanol and vegetable oil at temperatures between 13 and 43 °C was evaluated. Diffusion of the α-Tocopherol from the PT2.5 films to ethanol showed a Fick’s behavior with diffusion coefficients (D) at levels between 10−11 and 10−10 cm2/s and with 26.9–99% of release. Diffusion of α-Tocopherol to oil was slower than to ethanol with 5.1–12.9% of release. However, it was enough to delay the induction of the oxidation of soybean oil stored in contact with the PT2.5 film at 20 and 30 °C, compared with that of oil in contact with the PT0 film. The processing conditions and the temperature of diffusion process had an effect on the reduction of the weight average molecular weight (MW) of PLA. PLA packaging added with α-Tocopherol could be used for protection of oily foods stored at room temperature.