Influence of γ-irradiation on mechanical and water barrier properties of corn protein-based films

Effect of γ-irradiation on zein, a predominant corn protein, was studied to improve performance of the zein films in packaging applications. This goal has been achieved by irradiating zein film forming solutions with Co60 gamma rays (10.5 kGy/h) at the doses of 10, 20, 30, and 40 kGy. Gamma-irradiation of zein solutions caused a disruption and/or an aggregation of the zein molecules according to viscosity measurements. Structural changes of the polypeptides were also evaluated by CD spectrometry. The tensile strength of zein films was decreased with increasing radiation doses with a slight increase was noticed at a radiation dose of 20 kGy, while a noticeable increase in elongation was exhibited with increasing radiation dose. However, a slight decrease was noticed at 20 kGy. Alteration of zein molecular conformation by radiation treatment significantly reduced the water vapour permeability. Measurement of Hunter colour values indicated that radiation caused a significant decrease in Hunter b values.