The Effect of Glycerol on Tensile Strength, Elongation, and Young's Modulus of Smart Edible Film from Rabbit Skin Gelatin with Purple Sweet Potato Solution

Abstract

Smart edible film is a biodegradable packaging material that can function not only as a physical barrier but also as an indicator of food quality. This study aimed to evaluate the effect of glycerol concentration on the tensile strength, elongation, and Young's modulus of smart edible film produced from rabbit skin gelatin with purple sweet potato solution, and to determine the optimum glycerol concentration for producing the best mechanical characteristics. The experiment used five glycerol concentrations, namely 5% (P1), 10% (P2), 15% (P3), 20% (P4), and 25% (P5), with four replications for each treatment. The observed variables were tensile strength, elongation, and Young's modulus. Data were analyzed using analysis of variance (ANOVA), followed by Duncan's multiple range test to determine differences among treatments. The results showed that glycerol concentration had a significant effect (P < 0.05) on the tensile strength, elongation, and Young's modulus of the smart edible film. Increasing glycerol concentration decreased tensile strength and Young's modulus, while elongation increased up to a certain level. Based on the overall mechanical characteristics, the 20% glycerol treatment (P4) was considered the most suitable treatment because it provided a balanced combination of tensile strength (0.49 MPa), elongation (73.45%), and Young's modulus (0.66 MPa). These results indicate that 20% glycerol can produce a smart edible film that is sufficiently strong, flexible, and not overly rigid, making it a potential formulation for further development as environmentally friendly active food packaging. Therefore, the formulation may support the development of biodegradable packaging materials derived from livestock by-products and natural plant pigments.