Edible Chitosan/Acetylated Monoglyceride Films for Prolonged Release of Vitamin E and Antioxidant Activity

Abstract

α-Tocopherol-loaded chitosan films for pharmaceutical applications and food packaging purposes were designed to attain prolonged antioxidant activity. The films were prepared according to an emulsification/casting-solvent process from dispersions containing chitosan at 1.0 and 1.5% (w/w), combining five different proportions of α-tocopherol (ranging from 0 to 40% (w/w) with respect to chitosan) and two acetylated monoglyceride (AM) : α-tocopherol weight ratios (1 : 1 or 4 : 1). AM is a safe, edible, fully hydrogenated palm-based oil that provided adequate distribution of α-tocopherol in the films. Humidity at equilibrium, puncture strength and puncture deformation decreased as the content in α-tocopherol increased; no relevant effect of cross-linking in a glutaraldehyde atmosphere was observed. Degree of swelling and α-tocopherol release were tested in hydroalcoholic medium that mimic the polarity of the skin and certain foods. The films behaved as superabsorbent and sustained the release for more than 5 days; after 20 days, the antioxidant activity of α-tocopherol in the release medium was in some cases still as higher as that of a freshly prepared solution. The greater the content in α-tocopherol, the slower the release in percentage was. AM exerted a protective effect on α-tocopherol, but when incorporated at too high proportion made the films to have an oily aspect. In sum, the chitosan films showed suitable features to be used as components of α-tocopherol sustained release formulations and long-term antioxidant packaging materials.