Edible chitosan/acetylated monoglyceride films for prolonged release of vitamin E and antioxidant activity

Abstract

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. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013