Control of cross-linking reaction to tailor the properties of thin films based on gelatin

Lactose-modified gelatin films were prepared at two different pHs with the aim to control the cross-linking reaction between gelatin and lactose and thus, the properties of the resulting films. All the films obtained were homogeneous, transparent, and hydrophobic, but solution pH affected the extent of cross-linking. In particular, the films processed at the native pH showed low solubility, better barrier properties against light and higher tensile strength as a consequence of a higher degree of cross-linking. These results highlight the relevance of controlling the extent of cross-linking to design thin films with tailored properties.