Solubility and Permeability Properties of Edible Pectin-Soy Flour Films Obtained in the Absence or Presence of Transglutaminase

The permeability characteristics and water-solubility of edible pectin–soy flour films obtained in the absence or presence of the enzyme transglutaminase were investigated and compared with those possessed by both the commonly used high density polyethylene film and the biodegradable Mater-Bi® film. The soy protein transglutaminase-catalyzed crosslinking was found to determine a marked decrease in the solubility of the pectin–soy flour films both at different pH and in different denaturing conditions with respect to the films obtained in the absence of the enzyme, even though their solubility remains higher than that of the commercially available polyethylene and Mater-Bi® films. Transglutaminase treatment was also shown to significantly increase pectin–soy flour film barrier properties to oxygen, carbon dioxide and water vapour. In particular, the films obtained in the presence of the enzyme exhibited a permeability to oxygen and carbon dioxide even lower than that possessed by polyethylene films. Our results suggest a possible use of the transglutaminase-polymerized pectin–soy flour films as wrapping of food products requiring a packaging allowing low gas exchange with the environment. Furthermore, the application of these films as coatings to conventional oral dosage forms could provide a viable means of delivering drugs to the colon.