The gelatin was soaked in deionized distilled water at 40 C for
45 min. The mixture was then heated to 60 C until the solution became
homogeneous. Solution with concentration of 20% gelatin
was obtained. Poly(ethylene glycol) (PEG 400), content of 20%
based on dry gelatin, was added as a plasticizing agent. The gelatin
was crosslinked with dialdehyde starch (DAS, 7.4% based on dry
gelatin) or glutaraldehyde (GTA, 1.5% based on dry gelatin) at
60 C and pH 8–9. Gelatin modified with DAS and GTA is denoted
as DAS-Gel and GTA-Gel, respectively.