Design and evaluation of modified gelatin films to address the aging problem of soft capsule shells

The objective of this experiment was to modify the structure of gelatin using succinic anhydride in order to address the issue of ageing caused by the gelatin cross-linking reaction. The addition of succinic anhydride to the gelatin solution enabled the initiation of a chemical reaction, resulting in the formation of succinylated gelatin. The structure of the succinylated gelatin was characterized by Fourier transform infrared spectral analysis (FT-IR) and nuclear magnetic resonance spectroscopy (NMR). By comparing the disintegration time and mechanical properties of formaldehyde-treated gelatin, it was found that the disintegration time of formaldehyde-treated gelatin was much higher than that of acylated gelatin, and the change in mechanical properties was more pronounced. The stability and hygroscopicity of the two films before and after succinic anhydride modification were measured. The results of the moisture diffusion mechanism and scanning electron microscopy (SEM) analysis demonstrated that the moisture absorption capacity of the two films was essentially the same. The findings demonstrated that the alteration of the gelatin configuration through succinic anhydride incorporation exhibited a discernible anti-formaldehyde impact. Moreover, the hygroscopic ability of the two types of films was largely unchanged before and after the succinic anhydride modification, indicating that the modified gelatin had no significant impact on its hygroscopic property. In light of these findings, we postulate that the modification of gelatin with succinic anhydride may prove an effective strategy for achieving an anti-ageing effect. • The gelatin film modified with succinic anhydride was developed to address the aging problem of soft capsule . • According to the mechanical properties and disintegration time of the gelatin film treated with formaldehyde, the modified gelatin has a significant anti-aging effect. • The hygroscopic ability of gelatin film had no obvious change after chemical modification using succinic anhydride.