Development of Bioactive Agar-Based Bioplastics Enriched with Cocoa Pod Husk Extract: Structural, Barrie, and Antioxidant Properties

Department of Chemical Engineering, Faculty of Engineering, Universitas Gadjah Mada, Yogyakarta, Indonesia

^* Corresponding author: yuni_kusumastuti@ugm.ac.id

Abstract

The growing demand for eco-friendly food packaging has driven the development of biodegradable active films. This study developed novel agar-based films incorporating phenolic-rich cocoa pod husk (CPH) extract (10 - 25% w/w) and glycerol (30–50% w/w) using green deep eutectic solvent (DES) extraction. The optimal formulation (25% w/w CPH, 40% glycerol) demonstrated exceptional functionality. The antioxidant activity of bioplastics added with phenolic compounds of cocoa pod husk extract at 10, 15, and 25% w/w, analysed by the DPPH method, obtained results of 45.72 ± 0.27, 47.45 ± 0.06, and 56.85 ± 0.06, respectively, and the water vapour permeability was 907.26 g/m²day. The hydrogen bonding interaction among the components of the blend films led to enhanced structural, barrier, thermal stability, miscibility, antioxidant properties, and smooth surface morphology of the blend films. Characterization showed hydrogen bonds such as -OH between agar, glycerol, and phenolic CPH, C=O ester groups (FTIR), and homogeneous microstructure (SEM). DES extraction preserved bioactivity better than conventional methods. This study demonstrates the potential of agar/CPH films as sustainable active packaging for perishable foods, combining antioxidant/antimicrobial properties with mechanical strength, while addressing both food preservation and environmental sustainability challenges through circular economy principles.