INFLUENCE OF CRYSTALLINITY AND FUNCTIONAL GROUPS ON MECHANICAL PROPERTIES OF BIOCOMPOSITE FILMS FROM Bruguiera gymnorrhiza FRUIT FLOUR-IOTA CARRAGEENAN-CATFISH SKIN GELATIN (Clarias sp.)

Biocomposite films are thin, biodegradable materials composed of polysaccharides, proteins, and lipids, offering a sustainable alternative to synthetic plastics. This study investigated the influence of Bruguiera gymnorrhiza mangrove fruit flour (starch source), iota-carrageenan (hydrocolloid), and catfish (Clarias sp.) skin gelatin (protein source) on the physical and mechanical properties of biocomposite films. The research method was a laboratory experimental design, with a complete randomized design repeated 3 times. The research treatment used a mixture of ingredients, namely iota-carrageenan, mangrove fruit flour with different concentrations, and catfish skin gelatin with different processing methods. The functional group characteristics of the ingredients in the mixture were analyzed by FTIR, while the crystallinity index (IC) was determined using X-ray diffraction. Results showed that the presence of –OH, –NH₂, and –OSO₃⁻ groups influenced the formation of crystalline and amorphous regions, thereby significantly affecting hardness, elongation, tensile strength, thickness, water vapor transmission rate (WVTR), and moisture content (p < 0.05). The optimal formulation (1% iota-carrageenan, 2% type B gelatin, and 0.5% mangrove fruit flour) yielded films with balanced tensile strength and flexibility, suitable for potential packaging applications. The findings highlight the potential of underutilized marine and coastal biomass in developing value-added, biodegradable packaging materials, contributing to waste valorization and reduced reliance on petroleum-based plastics.