Effect of aging treatment on the physicochemical properties of collagen films

Aging treatment was used as a safe and green physical crosslinking method to successfully improve the physicochemical properties of collagen casing films. The aging treatment increased the Young's modulus (YM) of dry, wet, and boiled collagen films, as well as the tensile strength (TS) of wet and boiled collagen films to some extent. However, the highest aging temperature (80 degrees C) together with the higher relative humidity (RH) values (70% and 80%) led to the decreases in YM and TS and increases in elongation at break (EB). The aging treatment also improved the cooking performance of collagen films, like water absorption and shrinkage in boiling water, where the water absorption decreased to the range of 185%-102% and the shrinkage decreased to the range of 41.5%-21.5%. Collagen films after aging treatment had higher moisture contents than that of control film, and their moisture contents increased with increasing aging time and RH value. The thermal properties of collagen films was improved only at lower temperatures (< 130 degrees C) by aging treatment as shown from the thermogravimetric analysis results. Furthermore, the aging treatment did not significantly affect the chemical composition of collagen films but caused the denaturation of collagen triple helix structures at different degrees according to fourier transformation infrared spectroscopy, x-ray diffraction pattern, and differential scanning calorimetry analyses.