Enhancing starch/agar cryogels with demethylated lignin: Microstructure, functional properties, and application as biodegradable absorbent pads for inhibiting oxidation in fresh minced pork

Abstract

This study investigated the effects of incorporating demethylated lignin (DLG) on the microstructure and functional properties of starch/agar cryogels, which were subsequently applied as an eco-friendly absorbent pad to delay the oxidation of chilled pork mince. The research aims to provide theoretical support for developing food-active packaging materials derived from biodegradable bio-based cryogels. After demethylation, the cleavage of the β-O-4 bonds within the lignin structure led to the generation of supplementary ortho phenolic hydroxyl groups. The incorporation of DLG affected the double helix structure of starch, which promoted non-covalent interactions between starch and agar, thereby enhancing the thermal stability of the cryogels. The pore structure of the cryogels became progressively more open with increasing DLG concentration. Although the more open pore structure marginally reduced the compression strength compared to that of pure starch cryogel, it significantly improved water absorption (from 440 % to 567 %) and inhibition of ABTS free radicals (from 91.6 % to 97.3 %). The antioxidant experiment of chilled pork experiment demonstrated that the absorbent pad significantly improved meat color and inhibited myoglobin and lipid oxidation. Throughout the 10-day storage period, it reduced malondialdehyde levels in meat samples to 1.34 ± 0.08 mg/kg. The DLG-loaded starch/agar cryogel demonstrates potential as an active food packaging material due to its enhanced water absorption capacity and antioxidant property.