Functional Biodegradable Agar Based Films from Polyphenol-Rich Matcha Extracts via Deep Eutectic Solvents: From Microstructure to Bioactivity

Abstract

The increasing demand for sustainable alternatives to petroleum-based plastics highlights the need for innovative bioactive packaging systems. This study aimed to develop agar-based biodegradable films co-incorporating deep eutectic solvents (DES) and a DES-extracted, polyphenol-rich matcha extract. Matcha extracts were obtained via ultrasonic-assisted extraction using binary and ternary DES, and their phenolic profiles and quantities were determined by LC-HRMS. During film casting, DES and the DES-extracted matcha were directly incorporated into the agar matrix, with DES simultaneously serving as extraction solvent and plasticizer. Structural and physicochemical analyses (FTIR, SEM, DSC, contact angle, transparency, moisture content, and swelling index) showed that DES strengthened hydrogen bonding relative to controls, improved film structure, and increased thermal stability. Films containing DES-extracted matcha exhibited higher UV-blocking, controlled moisture retention, and suitable optical properties. Antimicrobial tests indicated selective inhibition of Gram-positive bacteria and Candida albicans, while blueberry challenge tests confirmed suppression of microbial growth and delayed spoilage, particularly for MDES2. Overall, DES proved an effective green solvent for extracting matcha phenolics and a functional film component, yielding matcha-DES films that offer an effective, sustainable route to active packaging aligned with green chemistry principles.