Protein Structure and Network Orientation in Edible Films Prepared by Spinning Process

Biodegradable film was prepared by spinning soy protein isolate in a coagulating buffer. Tensile properties and molecular structure of the film were investigated. FTIR results showed that no secondary structure differences appeared between protein film and isolate. The protein aggregation observed in the isolate was increased by the immersion and dispersion of the isolate in the isoelectrical pH buffer. Fluorescence spectroscopy did not demonstrate tertiary structural differences between isolate and film. Stretching the film in two orthogonal directions did not result in significant differences of tensile properties (p≤0.05), indicating no network orientation. Therefore, the film structure could be the result of a random aggregation of proteins displaying a globular shape.