Stabilization of lipids in a biodegradable zein-oleate film by incorporation of antioxidants

Zein has been studied extensively for use as an edible, biodegradable food film. To function as such, as much as 40-50% oleic acid is added as a plasticizing agent. Over the course of time, these films became discolored and developed off-odors. It was speculated that this was due to oxidation of incorporated oleic acid. This study sought to reduce oxidative changes in film lipids by incorporation of antioxidants. Incorporation of 4,000 ppm of BHA into the films eliminated peroxide formation during accelerated UV storage conditions. Gas chromatography and headspace (GC-HS) chromatography revealed that total volatile components of UV-treated control films were 9× higher than fresh control volatiles. Comparison of the profiles led to the demonstration of major differences in peaks of a specific region, suggesting the presence of oxidation products in that region. Differences in UV-treated BHA films and UV-treated control films appeared in the same specific region of the chromatogram. Solid-phase microextraction analysis of volatile components of the various film components and films also demonstrated a major increase in peaks associated with oxidation due to UV treatment and reduction of oxidative products in UV-treated BHA films. Antioxidant treatment was thus found to protect the films against oxidative deterioration.